Increased plant disease resistance by expression of a glycine-rich protein
REFERENCE TO SEQUENCE LISTING SUBMITTED ELECTRONICALLY
The Sequence Listing, which is a part of the present disclosure, is submitted concurrently with the specification as an XML file. The name of the file containing the Sequence Listing is “2230017US01_SeqListing. xml” created on 30 January 2024, and 36,864 bytes in size) is submitted concurrently with the instant application, and the entire contents of the Sequence Listing are incorporated herein by reference.
The present invention relates to genes, materials and methods for improving plant health, preferably against infection by phythopathogenic microorganisms. Furthermore, the invention pertains to methods and uses of such genes and materials for creating correspondingly beneficial plant as well as plant material. The present invention also provides products obtainable from such plant or plant material. To this end the invention focuses on facilitating or increasing the production and/or accumulation of a glycine-rich protein, fragment or homolog thereof in a plant or plant material compared to corresponding wild type plant or plant material. The invention also relates to plant and plant material having an increased resistance against fungal pathogens and to material and methods to create or use such plants and plant material or to produce products therefrom.
BACKGROUND OF THE INVENTION
The cultivation of agricultural crop plants serves mainly for producing foodstuffs for humans and animals. Plant pathogenic organisms and particularly fungi have resulted in severe reductions in crop yield in the past, in worst cases leading to famine. Monocultures in particular, which are routine nowadays, are highly susceptible to an epidemic-like spread of diseases. The result is markedly reduced yields. To date, the pathogenic organisms have been controlled mainly by using pesticides. Nowadays, the possibility of directly modifying the genetic disposition of a plant or pathogen is also open to man. Alternatively, natural occurring fungicides produced by the plants after fungal infection can be synthesized and applied to the plants. Resistance generally describes the ability of a plant to prevent, or at least curtail the infestation and colonization by a harmful pathogen. Different mechanisms can be discerned in the naturally occurring resistance, with which the plants fend off colonization by phytopathogenic organisms (Schopfer and Brennicke (1999) Pflanzenphysiologie, Springer Verlag, Berlin-Heidelberg, Germany).
With regard to the race specific resistance, also called host resistance, a differentiation is made between compatible and incompatible interactions. In the compatible interaction, an interaction occurs between a virulent pathogen and a susceptible plant. The pathogen survives, and may build up reproduction structures, while the host is seriously hampered in development or dies off. An incompatible interaction occurs on the other hand when the pathogen infects the plant but is inhibited in its growth before or after weak development of symptoms (mostly by the presence of R genes of the NBS-LRR family, see below). In the latter case, the plant is resistant to the respective pathogen (Schopfer and Brennicke, vide supra). However, this type of resistance is mostly specific for a certain strain or pathogen. In both compatible and incompatible interactions, a defensive and specific reaction of the host to the pathogen occurs. In nature, however, this resistance is often overcome because of the rapid evolutionary development of new virulent races of the pathogens (Neu et al. (2003) American Cytopathol. Society, MPMI 16 No. 7: 626-633).
Most pathogens are plant species specific. This means that a pathogen can induce a disease in a certain plant species, but not in other plant species (Heath (2002) Can. J. Plant Pathol. 24: 259-264). The resistance against a pathogen in certain plant species is called non-host resistance. The non-host resistance offers strong, broad, and permanent protection from phytopathogens. Genes providing non-host resistance provide the opportunity of a strong, broad and permanent protection against certain diseases in non-host plants. In particular, such a resistance works for different strains of the pathogen.
Fungi are distributed worldwide. Approximately 100 000 different fungal species are known to date. Thereof, rusts are of great importance. They can have a complicated development cycle with up to five different spore stages (spermatium, aecidiospore, uredospore, teleutospore and basidiospore).
During the infection of plants by pathogenic fungi, different phases are usually observed. The first phases of the interaction between phytopathogenic fungi and their potential host plants are decisive for the colonization of the plant by the fungus. During the first stage of the infection, the spores become attached to the surface of the plants, germinate, and the fungus penetrates the plant. Fungi may penetrate the plant via existing ports such as stomata, lenticels, hydathodes and wounds, or else they penetrate the plant epidermis directly as the result of mechanical force with the aid of cell wall digesting enzymes. Specific infection structures are developed for penetration of the plant. To counteract, plants have developed physical barriers, such as wax layers, and chemical compounds having antifungal effects to inhibit spore germination, hyphal growth or penetration.
The soybean rust Phakopsora pachyrhizi directly penetrates the plant epidermis. After growing through the epidermal cell, the fungus reaches the intercellular space of the mesophyll, where the fungus starts to spread through the leaf. To acquire nutrients, the fungus penetrates mesophyll cells and develops haustoria inside the mesophyll cells. During the penetration process the plasma membrane of the penetrated mesophyll cell stays intact. It is a particularly troubling feature of Phakopsora rusts that these pathogens exhibit an immense variability, thereby overcoming novel plant resistance mechanisms and novel fungicide activities within a few years and sometimes already within one Brazilian growing season.
The initial step of pathogenesis of Asian soybean rust disease is the initial penetration of the fungus through the plant cuticule into the epidermal cell. The plant cuticle is an extracellular hydrophobic layer that covers the aerial epidermis and that consists of two major components, the polymer cutin and cuticular waxes (for review about plant cuticle see Yeats TH, Rose JK. The formation and function of plant cuticles. Plant Physiol. 2013;163(1):5-20). The cuticle provides protection against desiccation, external environmental stresses, and pathogens. For example, it has been shown that lower cutin amounts in tomato “cd” mutants are associated with increased susceptibility to Botrytis cinerea (Isaacson et al., 2009). To facilitate penetration through the cuticle many fungal pathogens secrete enzymes to degrade or weaken the cuticle, such as e.g. cutinases, a class of small, nonspecific esterases that hydrolyze the cutin polymer. In addition to cutin also the epicuticular waxes play an important role in pathogen development and defence. For example, it has been shown that the “inhibitor of rust tube germinationl” (irg 1 ) mutant of M. truncatula showed less epicuticular wax crystals on the abaxial leaf surface and a strong decrease in wax primary alcohol groups. This surface alteration led to an increased resistance against the fungal pathogens Phakopsora pachyrhizi, Puccinia emaculata and the anthracnose fungus C. trifolii (Uppalapati et al., 2012). The authors found that IRG1 codes for a Cys(2)His(2) zinc finger transcription factor also called PALM1.
Fusarium species are important plant pathogens that attacks a wide range of plant species including many important crops such as maize and wheat. They cause seed rots and seedling blights as well as root rots, stalk rots and ear rots. Pathogens of the genus Fusarium infect the plants via roots, silks or previously infected seeds or they penetrate the plant via wounds or natural openings and cracks. After a very short establishment phase the Fusarium fungi start to secrete mycotoxins such as trichothecenes, zearalenone and fusaric acid into the infected host tissues leading to cell death and maceration of the infected tissue. Feeding on dead tissue, the fungus then starts to spread through the infected plant leading to severe yield losses and decreases in quality of the harvested grain.
Immediately after recognition of a potential pathogen the plant starts to elicit defense reactions. Mostly the presence of the pathogen is sensed via so called PAMP receptors, a class of transmembrane receptor like kinases (RLKs) or receptor-like proteins (RLPs) recognizing conserved pathogen associated molecules (e.g. flagellin or chitin). The molecular mechanism of defense activation by RLKs and RLPs is quite complex and requires several co-receptors (for review see Yu TY, Sun MK, Liang LK. Receptors in the Induction of the Plant Innate Immunity. Mol Plant Microbe Interact. 2021 Jun;34(6):587-601). One important step in the PAMP signaling cascade is the termination of the signal by degradation or recycling of the receptor complex via endocytosis and the formation of endosomes. Again, the molecular mechanism of the endocytosis is not fully resolved, and it might be dependent on the specific RLK complex and environmental factors. Nevertheless, it had been shown that sterol molecules are involved in such endocytic processes (Yaning Cui, Xiaojuan Li, Meng Yu, Ruili Li, Lusheng Fan, Yingfang Zhu, Jinxing Lin; Sterols regulate endocytic pathways during flg22- induced defense responses in Arabidopsis. Development 1 October 2018; 145 (19): dev165688).
Biotrophic phytopathogenic fungi depend for their nutrition on the metabolism of living cells of the plants. This type of fungi belongs to the group of biotrophic fungi, like many rust fungi, powdery mildew fungi or oomycete pathogens like the genus Phytophthora or Peronospora. Necrotrophic phytopathogenic fungi depend for their nutrition on dead cells of the plants, e.g. species from the genus Fusarium, Rhizoctonia or Mycospaerella. Soybean rust has occupied an intermediate position, since it penetrates the epidermis directly, whereupon the penetrated cell becomes necrotic. After the penetration, the fungus switches to an obligatory biotrophic lifestyle. The subgroup of the biotrophic fungal pathogens which follows essentially such an infection strategy are heminecrotrophic.
Soybean rust has become increasingly important in recent times. The disease is caused by the biotrophic rusts Phakopsora pachyrhizi (Sydow) and Phakopsora meibomiae (Arthur). They both belong to the class Basidiomycota, order Uredinales, family Phakopsoraceae. Both rusts infect a wide spectrum of leguminosic host plants. P. pachyrhizi is the more aggressive pathogen on soybean (Glycine max), and is therefore, at least currently, of great importance for agriculture. P. pachyrhizi can be found in nearly all tropical and subtropical soybean growing regions of the world. P. pachyrhizi is capable of infecting 31 species from 17 families of the Leguminosae in nature and is capable of growing on further 60 species in controlled conditions (Sinclair et al. (eds.), Proceedings of the rust workshop (1995), National Soybeana Research Laboratory, Publication No. 1 (1996); Rytter J.L. et al., Plant Dis. 87, 818 (1984)). P. meibomiae has been found in the Caribbean Basin and in Puerto Rico and has not caused substantial damage as yet.
P. pachyrhizi can currently be controlled in the field only by means of fungicides. Soybean plants with resistance to the entire spectrum of the isolates are not available. When searching for resistant soybean accessions, six dominant R genes of the NBS-LRR family, which mediate resistance of soybean to P. pachyrhizi, were discovered. The resistance they conferred was lost rapidly, as P. pachyrhizi develops new virulent races.
In recent years, fungal diseases, e.g. soybean rust, became more important in agricultural production. There was, therefore, a demand in the state of the art for developing methods to control fungi and to provide plants that resist fungal diseases. A lot of research has been performed on powdery and downy mildew infecting the epidermal layer of plants. However, the problem to cope with soybean rust, which infects the mesophyll or with Fusarium fungi that infect inaccessible inner tissues remains unsolved.
Glycine-rich proteins (GRPs) have been found in the cell walls of many higher plants and form a third group of structural protein components of the wall in addition to extensins and prolinerich proteins. Functionally GRPs are described to be involved in cell wall remodelling processes in growth and development (Ringli, C., Keller, B. & Ryser, U. Glycine-rich proteins as structural components of plant cell walls. CMLS, Cell. Mol. Life Sci. 58, 1430-1441 (2001).
There are only very few descriptions of Glycine-rich proteins to be involved in pathogen resistance. One of the few publications indicating an involvement GRPs in plant defence is describing a completely different family of GRPs, which is also rich in proline and therefore named GRPRP (glycine rich proline rich protein) focused, (Halder, T., Upadhyaya, G., Roy, S. et al. Glycine rich proline rich protein from Sorghum bicolor serves as an antimicrobial protein implicated in plant defence response. Plant Mol Biol 101 , 95-112 (2019).)
Nevertheless, GRPs are important constituent of an intact cell wall, so mutations and knockdowns of GRPs might lead to cellular stress reactions or cell death. For example the knock-down of the rice GRP GRDP1 leads to a lesion-mimic phenotype, showing the importance of GRPs in maintaining and monitoring cell integrity, which is also crucial in disease resistance (Xiaosheng Zhao, Tiancheng Qiu, Huijing Feng, Changfa Yin, Xunmei Zheng, Jun Yang, You-Liang Peng, Wensheng Zhao, A novel glycine-rich domain protein, GRDP1 , functions as a critical feedback regulator for controlling cell death and disease resistance in rice, Journal of Experimental Botany, Volume 72, Issue 2, 2 February 2021 , Pages 608-622)
Surprisingly, we could show that expression of a tomato GRP1 (Solanum lycopersicum GRP1, SIGRP1) in soybean leads to an increased resistance of the soybean to soybean rust fungus.
It was thus the object of the invention to provide materials and methods to improve plant disease resistance, particularly in crops, and preferably also reducing the negative impact on overall plant health and/or yield which the means of obtaining said improved pathogen resistance may entail. In particular, it was a preferred object of the invention to provide materials and methods which lead to plant material of heritably improved resistance against fungal pathogens with minimised reduction of overall plant health, wherein resistance preferably is directed against a rust fungus and most preferably a fungus in the genus Phakopsora, Fusarium, Sclerotinia, Alternaria, Corynespora, Cercospora, or Septoria.
By improving fungal resistance in soybean and other crop plants, the invention offers several advantages to farmers and to the environment. In particular, fungal diseases require expensive fungicide treatments to control, which can increase production costs. By improving fungal resistance, farmers can reduce the need for fungicides. Fungicides can be expensive, and their frequent application can contribute to a significant portion of a farmer's input costs. By reducing the dependence on fungicides, the invention advantageously allows farmers to save money and improve their profitability. Furthermore, by reducing the need for fungicide treatments, the invention advantageously also decreases the reliance on potentially harmful chemicals, thereby reducing the risk of human exposure to fungicides and improving the safety of crop production. The invention thus also allows to reduce chemical runoff and contamination of water sources or of soil. Furthermore, by reducing severity of infection and/or delaying the onset of disease, the invention allows to reduce or delay the contamination of neighbouring fields with fungal pathogen spores as described below. And by improving fungal resistance, in particular of soybean against Phakopsora rust pathogens, the quality of soybean seeds is improved, which can command a premium price. As soybean is an important source of protein for both humans and animals, improved fungal resistance helps ensure a stable supply of soybean and reduce the risk of food and feed shortages. Overall, increasing resistance against biotrophic or heminecrotrophic fungi, particularly against soybean rust, not only benefits farmers by reducing costs and improving profitability but also contributes to a healthier environment by minimizing the use of fungicides and their associated environmental and health risks.
SUMMARY OF THE INVENTION
Accordingly, the invention provides a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises a step of increasing the production and/or accumulation of a glycine-rich protein in the plant or plant material in comparison to a respective wild-type plant or plant material, the glycine-rich protein is preferably SIGRP1 protein.
The invention also provides a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises increasing the production and/or accumulation of the SIGRP1 protein having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with SEQ ID NO. 1 , 3, 5, 7, 9, 11 , 13, 15, 17, 19, and 21 , or a functional fragment thereof.
In another aspect, the invention provides a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises increasing the production and/or accumulation of the SIGRP1 protein in the plant or plant material, wherein the said SIGRP1 protein is encoded by i) an exogenous nucleic acid having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, or a functional fragment thereof or a splice variant thereof; or ii) an exogenous nucleic acid capable of hybridizing under stringent conditions with a complementary sequence of any of the nucleic acids according to i); or iii) an exogenous nucleic acid encoding the same SIGRP1 protein as the nucleic acids of i) to ii) above, but differing from the nucleic acids of i) to ii) above due to the degeneracy of the genetic code, wherein optionally the nucleic acid according to any of i) - iii) is operably linked with a promoter and a transcription termination sequence.
Furthermore, the invention provides a method for increasing or conferring fungal resistance in a plant or plant material, comprising the steps of 1) stably transforming a plant cell with at least one expression cassette comprising an exogenous nucleic acid encoding a SIGRP1 protein as defined in the invention, 2) regenerating a plant from the plant cell; and 3) expressing the said the SIGRP1 protein.
In one aspect of the invention, the method for increasing or conferring fungal resistance in a plant or plant material, wherein the fungal resistance is against at least one biotrophic or heminecrotrophic fungus, preferably against a rust fungus.
The invention further provides a method for production of a genetically modified plant or plant material having increased fungal resistance compared to a respective wild-type plant or wildtype plant material, comprising the steps of 1) introducing an exogenous nucleic acid encoding a SIGRP1 protein according to the invention into a plant or plant material; 2) generating a genetically modified plant or genetically modified plant material; and 3) expressing a SIGRP1 protein in the genetically modified plant or genetically modified plant material, wherein the SIGRP1 protein is encoded as defined in the invention.
In one aspect of the invention, the method for production of a genetically modified plant or plant material having increased fungal resistance, further comprising the steps of harvesting the seeds of the transgenic plant and planting the seeds and growing the seeds to plants, wherein the grown plants comprise anyone of the exogenous nucleic acid as defined according to the invention.
The invention additionally provides a plant or plant material having increased fungal resistance, wherein the plant or plant material comprises increased production and/or accumulation of a SIGRP1 protein in comparison to a respective wild-type plant or plant material, wherein the said plant or plant material is selected from the group consisting of members of the taxonomic family Fabaceae, Brassicaceae and Poaceae, preferably of family Fabaceae, and more preferably of genus Glycine.
In one aspect of the invention, the plant or plant material having increased fungal resistance comprising increased production and/or accumulation of a SIGRP1 protein having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with SEQ ID NO. 1 , 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 , or a functional fragment thereof.
In another aspect, the plant or plant material having increased fungal resistance according to the invention, wherein the plant or plant material comprising increased production and/or accumulation of a SIGRP1 protein, wherein the said SIGRP1 protein is encoded by i) an exogenous nucleic acid having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, or a functional fragment thereof or a splice variant thereof; or ii) an exogenous nucleic acid capable of hybridizing under stringent conditions with a complementary sequence of any of the nucleic acids according to i); or iii) an exogenous nucleic acid encoding the same SIGRP1 protein as the nucleic acids of i) to ii) above, but differing from the nucleic acids of i) to ii) above due to the degeneracy of the genetic code, wherein optionally the nucleic acid according to any of i) - iii) is operably linked with a promoter and a transcription termination sequence.
In another aspect of the invention, the plant or plant material having increased fungal resistance, wherein the plant or plant material is selected from a) the plant or plant material is a genetically modified crop plant, genetically modified plant material or the plant comprising increased production results form an artificially induced heritable mutation of the wild-type genome; and/or b) wherein the gene encoding SIGRP1 protein is integral in the genome of the plant or the plant material; and/or c) wherein the plant or plant material is homozygous for the gene encoding SIGRP1 protein or heterozygous for the gene encoding SIGRP1 protein, and/or d) wherein the plant or plant material, when in meiosis, is non-segregating or segregating for the gene encoding SIGRP1 protein, and/or e) wherein the gene encoding SIGRP1 protein is operably linked to a heterologous promoter, and/or f) wherein the gene encoding SIGRP1 protein is in the genome of the plant or plant material integrated at a different locus than the corresponding wild-type SIGRP1 protein gene. According to the invention, here any kind of combination of a) to f) is possible.
In a further aspect of the invention, the plant or the plant material having increased fungal resistance, wherein the plant or the plant material is selected from the group consisting of members of the taxonomic family Fabaceae, Brassicaceae and Poaceae preferably family Fabaceae, and more preferably subfamily Faboideae, preferably of taxonomic tribus Phaseoleae, more preferably of genus Cajanus, Canavalia, Glycine, Phaseolus, Psophocarpus, Pueraria or Vigna, even more preferably of species Cajanus cajan, Canavalia brasiliensis, Canavalia ensiformis, Canavalia gladiata, Glycine gracilis, Glycine max, Glycine soja, Phaseolus acutifolius, Phaseolus lunatus, Phaseolus maculatus, Psophocarpus tetragonolobus, Pueraria montana, Vigna angularis, Vigna mungo, Vigna radiata or Vigna unguiculata, even more preferably of species Glycine gracilis, Glycine max or Glycine soja, even more preferably of species Glycine max, taxonomic tribus Fabeae, more preferably of genus Lathyrus, Lens, Pisum or Vicia, even more preferably of species Lathyrus aphaca, Lathyrus cicera, Lathyrus hirsutus, Lathyrus ochrus, Lathyrus odoratus, Lathyrus sphaericus, Lathyrus tingitanus, Lens culi naris, Pisum sativum, Vicia cracca, Vicia faba or Vicia vellosa, taxonomic tribus Brassiceae, more preferably of genus Brassica, Crambe, Raphanus or Sinapis, even more preferably of species Brassica aucheri, Brassica balearica, Brassica barrelieri, Brassica bourgeaui, Brassica carinata, Brassica cretica, Brassica deflexa, Brassica desnottesii, Brassica drepanensis, Brassica elongata, Brassica fruticulosa, Brassica gravinae, Brassica hilarionis, Brassica incana, Brassica insularis, Brassica juncea, Brassica macrocarpa, Brassica maurorum, Brassica montana, Brassica napus, Brassica nigra, Brassica oleracea, Brassica oxyrrhina, Brassica procumbens, Brassica rapa, Brassica repanda, Brassica rupestris, Brassica souliei, Brassica spinescens, Brassica tournefortii, Brassica villosa or crosses of any of these species, even more preferably Brassica napus (rape), Brassica nigra (black mustard), Brassica oleracea (wild cabbage), Brassica rapa (field mustard) or crosses of any of these species, even more preferably Brassica napus species Raphanus sativus, species Sinapis alba, taxonomic tribus Andropogoneae, Bambuseae, Oryzeae, Poeae, Triticeae, more preferably of genus Saccharum, Zea, Oryza, Avena, Hordeum, Secale, Triticum, even more preferably of species Zea mays, Oryza sativa, Avena sativa, Avena strigosa, Hordeum marinum, Hordeum vulgare, Secale cereale or Triticum aestivum, wherein most preferably the plant is soybean.
In another aspect of the invention, the fungal pathogen according to the invention preferably is a fungus or a fungus-like organism. The plant or the plant material having increased fungal resistance, wherein the increased fungal resistance is against a rust fungus, preferably against a fungus of phylum Basidiomycota, more preferably of subphylum Pucciniomycotina, even more preferably of class Pucciniomycetes, even more preferably of order Pucciniales, much more preferably of family Araucariomycetaceae, Chaconiaceae, Coleosporiaceae, Cronartiaceae, Crossopsoraceae, Gymnosporangiaceae, Melampsoraceae, Milesinaceae, Ochropsoraceae, Phakopsoraceae, Phragmidiaceae, Pileolariaceae, Pucciniaceae, Pucciniosiraceae, Pucciniastraceae, Raveneliaceae, Rogerpetersoniaceae, Skierkaceae, Sphaerophragmiaceae, Tranzscheliaceae, Uropyxidaceae, Zaghouaniaceae, mitosporic Pucciniales and incertae sedis, even more preferably of genus Maravalia, Ochropsora, Olivea, Chrysomyxa, Coleosporium, Diaphanopellis, Cronartium, Endocronartium, Peridermium, Melampsora, Chrysocelis, Mikronegeria, Arthuria, Batistopsora, Cerotelium, Dasturella, Phakopsora, Prospodium, Arthuriomyces, Catenulopsora, Gerwasia, Gymnoconia, Hamaspora, Kuehneola, Phragmidium, Trachyspora, Triphragmium, Atelocauda, Pileolaria, Racospermyces, Uromycladium, Allodus, Ceratocoma, Chrysocyclus, Cumminsiella, Cystopsora, Endophyllum, Gymnosporangium, Miyagia, Puccinia, Puccorchidium, Roestelia, Sphenorchidium, Stereostratum, Uromyces, Hyalopsora, Melampsorella, Melampsoridium, Milesia, Milesina, Naohidemyces, Pucciniastrum, Thekopsora, Uredinopsis, Chardoniella, Dietelia, Pucciniosira, Diorchidium, Endoraecium, Kernkampella, Ravenelia, Sphenospora, Austropuccinia, Nyssopsora, Sphaerophragmium, Dasyspora, Leucotelium, Macruropyxis, Porotenus, Tranzschelia or Uropyxis, most preferably of species Phakopsora pachyrhizi, Phakopsora meibomiae, Puccinia graminis, Puccinia striiformis, Puccinia hordei or Puccinia recondite, and combination of these species.
The invention also provides a recombinant vector construct comprising a nucleic acid encoding a SIGRP1 protein selected from the group consisting of: i) an exogenous nucleic acid encoding a protein having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with SEQ ID NO. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21, or a functional fragment thereof; or ii) an exogenous nucleic acid having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, or a functional fragment thereof or a splice variant thereof; or iii) an exogenous nucleic acid capable of hybridizing under stringent conditions with a complementary sequence of any of the nucleic acids according to i) or ii); or iv) an exogenous nucleic acid encoding the same SIGRP1 protein as the nucleic acids of i) to iii) above, but differing from the nucleic acids of i) to iii) above due to the degeneracy of the genetic code.
The recombinant expression vector comprises a promoter, wherein the promoter is a constitutive, pathogen-inducible promoter, a mesophyll-specific promoter or an epidermis specific-promoter. The invention additionally provides a genetically modified plant or genetically modified plant material, transformed with at least one of the recombinant vector constructs according to the invention.
The invention provides use of a SIGRP1 protein or a nucleic acid encoding the SIGRP1 protein to increase fungal resistance in a plant, preferably wherein the increase of fungal resistance comprises the delay or reduced infection of a plant by a fungus.
The invention also provides a method of controlling a fungus in a field, preferably by reducing or delaying infection of plant in a field and/or reducing or delaying emission of fungal spores from the field, comprising the step of 1) planting seed from the plants according to the invention, and/or 2) optionally, one or more active agents including fungicide can be applied to the plants, by such as spraying or splashing.
The invention additional provides a method for evaluating the fungal resistance of the plant comprising the step of at least one step for detecting presence of a heterologous SIGRP1 gene or protein expression level in a plant material.
The invention further provides a molecular marker for selection of the plant or plant material according to the invention, comprising nucleic acid for detecting SIGRP1 in a plant material, wherein the nucleic acid is selected from the group consisting of 1) primer sequence of the SIGRP1 protein having the SEQ ID NO. 23 or SEQ ID NO. 24, or 2) probe sequence of the SIGRP1 protein having the SEQ ID NO. 25. In another aspect of the invention, it is provided that use of the molecular maker for selecting a plant or a plant material having SIGRP1 protein induced fungal resistance.
The invention also provides harvestable part of a plant according to the invention, wherein the harvestable part of the plant comprises an exogenous nucleic acid encoding the SIGRP1 protein, wherein the harvestable part is a seed of the plant, preferably genetically modified seed of the genetically modified plant.
In an additional aspect, the invention provides dead and/or non-propagative plant material derived from a plant or from the harvestable part of the plant according to the invention, wherein the dead and/or non-propagative plant material comprises the exogenous nucleic acid encoding the SIGRP1 protein as defined in the invention.
The invention also provides product derived from a plant or from the harvestable part of the plant, wherein the product comprises the exogenous nucleic acid encoding the SIGRP1 protein as defined in the invention, wherein the product is preferably a soy product, more preferably soybeans, soy oil or soy meal.
The invention further provides the use of the plant according to the invention for modifying genetic variation in a plant population.
The invention also provides method for breeding a fungal resistant crop plant comprising 1) crossing the plant according to the invention, or the plant obtainable by the method according to the invention with a second plant; 2) obtaining seed from the cross of step 1); 3) planting said seeds and growing the seeds to plants; and 4) selecting from said plants expressing the SIGRP1 protein as defined in the invention. Disclosed is also a method for producing a plant or plant material having increased pathogen resistance comprising introducing the SIGRP1 protein encoded as defined in the invention, by using genome editing, preferably using a CRISPR system.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 Schematic illustration of scoring system used to determine the level of diseased leaf area of wildtype and transgenic soy plants against the rust fungus P. pachyrhizi
Figure 1 shows the scoring system used to determine the level of diseased leaf area of wildtype and transgenic soy plants against the rust fungus P. pachyrhizi (as described in GODOY, C.V., KOGA, L.J. & CANTERI, M.G. Diagrammatic scale for assessment of soybean rust severity. Fitopatologia Brasileira 31 :063-068. 2006.)
Figure 2 schematic illustration of the plant transformation vector harboring the SIGRP1 protein
Figure 3 shows the amino acid sequence of Solanum lycopersicum GRP1 and nucleic acid encoding of Solanum lycopersicum GRP1
Figure 4 shows the result of the disease scoring of transgenic soy plants expressing SIGRP1 under a constitutive parsley ubiquitin promoter in T1 generation in greenhouse.
For the analysis of the constitutively expressed SIGRP1 , 55 transgenic T1 soybean plants (from 5 independent events) expressing SIGRP1 and 43 non-transgenic wild type control plants (same genetic background as transgenics) were inoculated with spores of Phakopsora pachyrhizi. The expression of SIGRP1 was checked by RT-PCR. The evaluation of the diseased leaf area on all leaves was performed 14 days after inoculation by imaging. The average of the percentage of the leaf area showing fungal colonies or strong yellowing/browning on all leaves was considered as diseased leaf area. The average diseased leaf area of all transgenic events (black bar) is shown in comparison to control (diagonally striped bar, labeled wild type control) In average the constitutive overexpression of SIGRP1 significantly (one sided t-test, p=0.056) reduces the diseased leaf area in comparison to non- transgenic control plants by 24.6% relative.
Figure 5 shows the absolute reduction of the Area Under Disease Progression Curve (AUDPC) of 3 independent events in T2 generation (grey bars) expressing SIGRP1 constitutively, in comparison to non-transgenic control (set to 0) in 2 locations and 2 treatments.
Negative values indicate less disease (= higher resistance) of the transgenic events. Bars of the same color indicate the result of the same event in different treatments or locations. Field trials were performed at 2 locations of Campinas (SP) and Uberlandia (MG). Both the field trials were run without any fungicide treatment (no treatment) and with one fungicide treatment at the onset of ASR disease (~35 - 40 days after planting) to increase variability of disease pressure to prove robustness and stability of the resistance increasing effect. The asterix indicates a statistically significant difference between transgenic and wild type control in the various disease ratings over the season (95% confidence level using Dunnett's LSD) BRIEF DESCRIPTION OF THE SEQUENCES
DETAILED DESCRIPTION OF THE INVENTION
The current invention is focused on the application of SIGRP1 protein for the protection of plants against fungal infection and progress of such infective diseases. The invention is described in detailed as follows.
The technical teaching of the invention is expressed herein using the means of language, in particular by use of scientific and technical terms. However, the skilled person understands that the means of language, detailed and precise as they may be, can only approximate the full content of the technical teaching, if only because there are multiple ways of expressing a teaching, each necessarily failing to completely express all conceptual connections, as each expression necessarily must come to an end. With this in mind the skilled person understands that the subject matter of the invention is the sum of the individual technical concepts signified herein or expressed in a pars-pro-toto way by the innate constrains of a written description. In particular, the skilled person will understand that the signification of individual technical concepts is done herein as an abbreviation of spelling out each possible combination of concepts as far as technically sensible, such that for example the disclosure of three concepts or embodiments A, B and C are a shorthand notation of the concepts A+B, A+C, B+C, A+B+C. In particular, fallback positions for features are described herein in terms of lists of converging alternatives or instantiations. Unless stated otherwise, the invention described herein comprises any combination of such alternatives. The choice of more or less preferred elements from such lists is part of the invention and is due to the skilled person’s preference for a minimum degree of realization of the advantage or advantages conveyed by the respective invention. Such multiple combined instantiations represent the adequately preferred form(s) of the invention.
As used herein, terms in the singular and the singular forms like "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to "plant", "the plant" or "a plant" also includes a plurality of plants; also, depending on the context, use of the term "plant" can also include genetically similar or identical progeny of that plant or plants derived therefrom by crossing; use of the term "a nucleic acid" optionally includes, as a practical matter, many copies of that nucleic acid molecule; similarly, the term "probe" optionally (and typically) encompasses many similar or identical probe molecules. Also as used herein, the word "comprising" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
As used herein, the term "and/or" refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or"). The term “comprising” also encompasses the term “consisting of”.
The term "about", when used in reference to a measurable value, for example an amount of mass, dose, time, temperature, sequence identity and the like, refers to a variation of ± 0.1%, 0.25%, 0.5%, 0.75%, 1 %, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15% or even 20% of the specified value as well as the specified value. Thus, if a given composition is described as comprising "about 50% X," it is to be understood that, in some embodiments, the composition comprises 50% X whilst in other embodiments it may comprise anywhere from 40% to 60% X (i.e., 50% ± 10%).
As used herein, the term "gene" refers to a biochemical information which, when materialized in a nucleic acid, can be transcribed into a gene product, i.e. a further nucleic acid, preferably an RNA, and preferably also can be translated into a peptide or polypeptide. The term is thus also used to indicate the section of a nucleic acid resembling said information and to the sequence of such nucleic acid (herein also termed "gene sequence").
Also as used herein, the term "allele" refers to a variation of a gene characterized by one or more specific differences in the gene sequence compared to the wild type gene sequence, regardless of the presence of other sequence differences. Alleles or nucleotide sequence variants of the invention have at least, in increasing order of preference, 30%, 40%, 50%, 60%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%-84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% nucleotide "sequence identity" to the nucleotide sequence of the wild type gene. Correspondingly, where an "allele" refers to the biochemical information for expressing a peptide or polypeptide, the respective nucleic acid sequence of the allele has at least, in increasing order of preference, 30%, 40%, 50%, 60%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%-84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% amino acid "sequence identity" to the respective wild type peptide or polypeptide. Mutations or alterations of amino or nucleic acid sequences can be any of substitutions, deletions or insertions; the terms "mutations" or "alterations" also encompass any combination of these. Hereinafter, all three specific ways of mutating are described in more detail by way of reference to amino acid sequence mutations; the corresponding teaching applies to nucleic acid sequences such that "amino acid" is replaced by "nucleotide".
The present invention accordingly provides a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises a step of increasing the production and/or accumulation of a glycine-rich protein in the plant or plant material in comparison to a respective wild-type plant or plant material, the glycine-rich protein is preferably SIGRP1 protein.
The term "resistance" as used herein refers to an absence or reduction of one or more disease symptoms in a plant caused by a plant pathogen. Resistance generally describes the ability of a plant to prevent, or at least curtail the infestation and colonization by a harmful pathogen. Different mechanisms can be discerned in the naturally occurring resistance, with which the plants fend off colonization by phytopathogenic organisms (Schopfer and Brennicke (1999) Pflanzenphysiologie, Springer Verlag, Berlin-Heidelberg, Germany).
The term "plant" is used herein in its broadest sense as it pertains to organic material and is intended to encompass eukaryotic organisms that are members of the taxonomic kingdom plantae, examples of which include but are not limited to monocotyledon and dicotyledon plants, vascular plants, vegetables, grains, flowers, trees, herbs, bushes, grasses, vines, ferns, mosses, fungi and algae, etc, as well as clones, offsets, and parts of plants used for asexual propagation (e.g. cuttings, pipings, shoots, rhizomes, underground stems, clumps, crowns, bulbs, corms, tubers, rhizomes, plants/tissues produced in tissue culture, etc.). Unless stated otherwise, the term "plant" refers to a whole plant, any part thereof, or a cell or tissue culture derived from a plant, comprising any of: whole plants, plant components or organs (e.g., leaves, stems, roots, etc.), plant tissues, seeds, plant cells, and/or progeny of the same. A plant cell is a biological cell of a plant, taken from a plant or derived through culture from a cell taken from a plant.
As used herein, the term "plant" includes whole plants, including descendants or progeny thereof. As used herein unless clearly indicated otherwise, the term "plant" intends to mean a plant at any developmental stage. Preferably, the plant according to the present invention are (predominantly) self-pollinating, i.e. a significant portion of the seeds produced result from self- pollination and not cross-pollination. Cross-pollination, also called allogamy, occurs when pollen is delivered from the stamen of one flower to the stigma of a flower on another plant of the same species. Self-pollination, as opposed to cross-pollination refers to fertilization of ovules/female gametes in a plant by pollen from the same plant. Self- pollination occurs when pollen from one flower pollinates the same flower or other flowers of the same individual. Self- pollination may include autogamy, where pollen is transferred to the female part of the same flower; or geitonogamy, when pollen is transferred to another flower on the same plant. In certain embodiments, self-pollination involves cleistogamy. Preferably at least 25% of the seeds produced result from self-pollination, more preferably at least 50%, even more preferably as at least 75%, most preferably at least 90%. The term “plant part” includes any part or derivative of the plant, including particular plant tissues or structures, plant cells, plant protoplast, plant cell or tissue culture from which plants can be regenerated, plant calli, plant clumps and plant cells that are intact in plants or parts of plants, such as seeds, kernels, cobs, flowers, cotyledons, leaves, stems, buds, roots, root tips, stover, and the like. Plant parts may include processed plant parts or derivatives, including flower, oils, extracts etc. "Parts of a plant" are e.g. shoot vegetative organs/structures, e.g., leaves, stems and tubers; roots, flowers and floral organs/structures, e.g. bracts, sepals, petals, stamens, carpels, anthers and ovules; seed, including embryo, endosperm, and seed coat; fruit and the mature ovary; plant tissue, e.g. vascular tissue, ground tissue, and the like; and cells, e.g. guard cells, egg cells, pollen, trichomes and the like; and progeny of the same. Parts of plants may be attached to or separate from a whole intact plant. Such parts of a plant include, but are not limited to, organs, tissues, and cells of a plant, and preferably seeds. A "plant cell" is a structural and physiological unit of a plant, comprising a protoplast and a cell wall. The plant cell may be in form of an isolated single cell or a cultured cell, or as a part of higher organized unit such as, for example, plant tissue, a plant organ, or a whole plant. "Plant cell culture" means cultures of plant units such as, for example, protoplasts, cell culture cells, cells in plant tissues, pollen, pollen tubes, ovules, embryo sacs, zygotes and embryos at various stages of development. "Plant material" refers to leaves, stems, roots, flowers or flower parts, fruits, pollen, egg cells, zygotes, seeds, cuttings, cell or tissue cultures, or any other part or product of a plant. This also includes callus or callus tissue as well as extracts (such as extracts from taproots) or samples. A "plant organ" is a distinct and visibly structured and differentiated part of a plant such as a root, stem, leaf, flower bud, or embryo. "Plant tissue" as used herein means a group of plant cells organized into a structural and functional unit. Any tissue of a plant in planta or in culture is included. This term includes, but is not limited to, whole plants, plant organs, plant seeds, tissue culture and any groups of plant cells organized into structural and/or functional units. The use of this term in conjunction with, or in the absence of, any specific type of plant tissue as listed above or otherwise embraced by this definition is not intended to be exclusive of any other type of plant tissue.
As used herein, "wildtype" or "corresponding wildtype plant" means the typical form of an organism or its genetic material, as it normally occurs, as distinguished from e.g. mutagenized and/or recombinant forms. Similarly, by "control cell" or "similar, wildtype, plant, plant tissue, plant cell or host cell" is intended a plant, plant tissue, plant cell, or host cell, respectively, that lacks the particular polynucleotide of the invention that are disclosed herein. The use of the term "wildtype" is not, therefore, intended to imply that a plant, plant tissue, plant cell, or other host cell lacks recombinant DNA in its genome, and/or does not possess fungal resistance characteristics that are different from those disclosed herein.
In one aspect of the invention, provided is a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises increasing the production and/or accumulation of the SIGRP1 protein having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with SEQ ID NO. 1 , 3, 5, 7, 9, 11 , 13, 15, 17, 19, and 21 , or a functional fragment thereof.
In another aspect, provided is a method for increasing or conferring fungal resistance in a plant or plant material, wherein the method comprises increasing the production and/or accumulation of the SIGRP1 protein in the plant or plant material, wherein the said SIGRP1 protein is encoded by i) an exogenous nucleic acid having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, or a functional fragment thereof or a splice variant thereof; or ii) an exogenous nucleic acid capable of hybridizing under stringent conditions with a complementary sequence of any of the nucleic acids according to i); or iii) an exogenous nucleic acid encoding the same SIGRP1 protein as the nucleic acids of i) to ii) above, but differing from the nucleic acids of i) to ii) above due to the degeneracy of the genetic code, wherein optionally the nucleic acid according to any of i) - iii) is operably linked with a promoter and a transcription termination sequence.
The protein or polypeptide sequences having identity with SEQ I D NO. 1 , 3, 5, 7, 9, 11 , 13, 15, 17, 19, and 21 , or a functional fragment thereof; or those exogenous nucleic acid encoding having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, have sequence homology and originated from different organism. The sequences can include introns, noncoding sequence of SIGRP1 protein.
The most preferably the SIGRP1 protein sequence having SEQ ID NO. 1. The most preferably exogenous nucleic acid having identity with SEQ ID NO. 2.
“Exogenous nucleic acid” refers to the ‘DNA that originates from outside of an organism’ and is typically introduced artificially into cells. This can be done for a variety of reasons such as genetic engineering, gene therapy, or to study gene function. Exogenous nucleic acid can be introduced into cells using various techniques such as transformation, transfection, electroporation, microinjection, and viral vectors. In the present invention “exogenous nucleic acid” and “heterologous nucleic acid” can have the same meaning.
The term "functional linkage" or "operably linked" with respect to regulatory elements is to be understood as meaning the sequential arrangement of a regulatory element (including but not limited thereto a promoter) with a nucleic acid sequence to be expressed and, if appropriate, further regulatory elements (including but not limited thereto a terminator) in such a way that each of the regulatory elements can fulfil its intended function to allow, modify, facilitate or otherwise influence expression of said nucleic acid sequence. For example, a control sequence is placed at an appropriate position relative to the coding sequence of the polynucleotide sequence such that the control sequence directs the expression of the coding sequence of a polypeptide.
The term “functional” means that the respective plant, plant part or plant cell is more likely to withstand an attempted infection by the pathogenic fungus, preferably Phakopsora pachyrhizi.
According to the present invention, the production and/or accumulation of the SIGRP1 protein in the plant or plant material can results in functional or biological activities changes in the plant or plant material. The term “biological activities” refers to a result of certain effects from exposure to a molecule; these affect a metabolic or physiological response. Biological activity is defined as being applied to the simplest and most complex reaction and molecular systems. There are many sorts of biological activities, and these activities can be studied in vivo and in vitro. Biological activity always depends on the dose given to the living organism, so it is logical to show either beneficial or adverse effects that range from low to high. Absorption, distribution, metabolism, and excretion are the main action used to measure biological activity. Protein or nucleic acid variants may be defined by their sequence identity when compared to a parent protein or nucleic acid. Sequence identity usually is provided as “% sequence identity” or “% identity”. To determine the percent-identity between two amino acid sequences in a first step a pairwise sequence alignment is generated between those two sequences, wherein the two sequences are aligned over their complete length (i.e., a pairwise global alignment). The alignment is generated with a program implementing the Needleman and Wunsch algorithm (J. Mol. Biol. (1979) 48, p. 443-453), preferably by using the program “NEEDLE” (The European Molecular Biology Open Software Suite (EMBOSS)) with the programs default parameters (gapopen=10.0, gapextend=0.5 and matrix=EBLOSUM62). The preferred alignment for the purpose of this invention is that alignment, from which the highest sequence identity can be determined.
The following example is meant to illustrate two nucleotide sequences, but the same calculations apply to protein sequences:
Seq A: AAGATACTG length: 9 bases
Seq B: GATCTGA length: 7 bases
Hence, the shorter sequence is sequence B.
Producing a pairwise global alignment which is showing both sequences over their complete lengths results in
Seq A: AAGATACTG-
Seq B :
The “I” symbol in the alignment indicates identical residues (which means bases for DNA or amino acids for proteins). The number of identical residues is 6.
The symbol in the alignment indicates gaps. The number of gaps introduced by alignment within the sequence B is 1. The number of gaps introduced by alignment at borders of sequence B is 2, and at borders of sequence A is 1 .
The alignment length showing the aligned sequences over their complete length is 10.
Producing a pairwise alignment which is showing the shorter sequence over its complete length according to the invention consequently results in:
Seq A:
Seq B :
Producing a pairwise alignment which is showing sequence A over its complete length according to the invention consequently results in:
Seq A:
Seq B : Producing a pairwise alignment which is showing sequence B over its complete length according to the invention consequently results in:
Seq A:
Seq B :
The alignment length showing the shorter sequence over its complete length is 8 (one gap is present which is factored in the alignment length of the shorter sequence).
Accordingly, the alignment length showing sequence A over its complete length would be 9 (meaning sequence A is the sequence of the invention), the alignment length showing sequence B over its complete length would be 8 (meaning sequence B is the sequence of the invention).
After aligning the two sequences, in a second step, an identity value shall be determined from the alignment. Therefore, according to the present description the following calculation of percent-identity applies:
%-identity = (identical residues I length of the alignment region which is showing the respective sequence of this invention over its complete length) *100. Thus, sequence identity in relation to comparison of two amino acid sequences according to the invention is calculated by dividing the number of identical residues by the length of the alignment region which is showing the respective sequence of this invention over its complete length. This value is multiplied with 100 to give “%-identity”. According to the example provided above, %-identity is: for sequence A being the sequence of the invention (6 / 9) * 100 = 66.7 %; for sequence B being the sequence of the invention (6 / 8) * 100 = 75%.
The term "hybridisation" as defined herein is a process wherein substantially complementary nucleotide sequences anneal to each other. The hybridisation process can occur entirely in solution, i.e. both complementary nucleic acids are in solution. The hybridisation process can also occur with one of the complementary nucleic acids immobilised to a matrix such as magnetic beads, Sepharose beads or any other resin. The hybridisation process can furthermore occur with one of the complementary nucleic acids immobilised to a solid support such as a nitro-cellulose or nylon membrane or immobilised by e.g. photolithography to, for example, a siliceous glass support (the latter known as nucleic acid arrays or microarrays or as nucleic acid chips). In order to allow hybridisation to occur, the nucleic acid molecules are generally thermally or chemically denatured to melt a double strand into two single strands and/or to remove hairpins or other secondary structures from single stranded nucleic acids.
The term “stringency” refers to the conditions under which a hybridisation takes place. The stringency of hybridisation is influenced by conditions such as temperature, salt concentration, ionic strength and hybridisation buffer composition. Generally, low stringency conditions are selected to be about 30°C lower than the thermal melting point (Tm) for the specific sequence at a defined ionic strength and pH. Medium stringency conditions are when the temperature is 20°C below Tm, and high stringency conditions are when the temperature is 10°C below Tm. High stringency hybridisation conditions are typically used for isolating hybridising sequences that have high sequence similarity to the target nucleic acid sequence. However, nucleic acids may deviate in sequence and still encode a substantially identical polypeptide, due to the degeneracy of the genetic code. Therefore, medium stringency hybridisation conditions may sometimes be needed to identify such nucleic acid molecules.
The “Tm” is the temperature under defined ionic strength and pH, at which 50% of the target sequence hybridises to a perfectly matched probe. The Tm is dependent upon the solution conditions and the base composition and length of the probe. For example, longer sequences hybridise specifically at higher temperatures. The maximum rate of hybridisation is obtained from about 16°C up to 32°C below Tm. The presence of monovalent cations in the hybridisation solution reduce the electrostatic repulsion between the two nucleic acid strands thereby promoting hybrid formation; this effect is visible for sodium concentrations of up to 0.4M (for higher concentrations, this effect may be ignored). Formamide reduces the melting temperature of DNA-DNA and DNA-RNA duplexes with 0.6 to 0.7°C for each percent formamide, and addition of 50% formamide allows hybridisation to be performed at 30 to 45°C, though the rate of hybridisation will be lowered. Base pair mismatches reduce the hybridisation rate and the thermal stability of the duplexes. On average and for large probes, the Tm decreases about 1°C per % base mismatch. The Tm may be calculated using the following equations, depending on the types of hybrids:
DNA-DNA hybrids (Meinkoth and Wahl, Anal. Biochem., 138: 267-284, 1984):
Tm= 81.5°C + 16.6xlog([Na+]{a}) + 0.41x%[G/C{b}] - 500x[L{c}]-1 - 0.61x% formamide
DNA-RNA or RNA-RNA hybrids:
Tm= 79.8 + 18.5 (log10[Na+]{a}) + 0.58 (%G/C{b}) + 11.8 (%G/C{b})2 - 820/L{c} oligo-DNA or oligo-RNAd hybrids: for <20 nucleotides: Tm= 2 ({ln}) for 20-35 nucleotides: Tm= 22 + 1.46 ({In} ) wherein:
{a} or for other monovalent cation, but only accurate in the 0.01-0.4 M range
{b} only accurate for %GC in the 30% to 75% range
{c} L = length of duplex in base pairs
{d} Oligo, oligonucleotide
{In} effective length of primer = 2* (no. of G/C)+(no. of A/T)
Non-specific binding may be controlled using any one of a number of known techniques such as, for example, blocking the membrane with protein containing solutions, additions of heterologous RNA, DNA, and SDS to the hybridisation buffer, and treatment with Rnase. For non-related probes, a series of hybridizations may be performed by varying one of (i) progressively lowering the annealing temperature (for example from 68°C to 42°C) or (ii) progressively lowering the formamide concentration (for example from 50% to 0%). The skilled artisan is aware of various parameters which may be altered during hybridisation and which will either maintain or change the stringency conditions.
Besides the hybridisation conditions, specificity of hybridisation typically also depends on the function of post-hybridisation washes. To remove background resulting from non-specific hybridisation, samples are washed with dilute salt solutions. Critical factors of such washes include the ionic strength and temperature of the final wash solution: the lower the salt concentration and the higher the wash temperature, the higher the stringency of the wash. Wash conditions are typically performed at or below hybridisation stringency. A positive hybridisation gives a signal that is at least twice of that of the background. Generally, suitable stringent conditions for nucleic acid hybridisation assays or gene amplification detection procedures are as set forth above. More or less stringent conditions may also be selected. The skilled artisan is aware of various parameters which may be altered during washing and which will either maintain or change the stringency conditions.
For example, typical high stringency hybridisation conditions for DNA hybrids longer than 50 nucleotides encompass hybridisation at 65°C in 1x SSC or at 42°C in 1x SSC and 50% formamide, followed by washing at 65°C in 0.3x SSC. Examples of medium stringency hybridisation conditions for DNA hybrids longer than 50 nucleotides encompass hybridisation at 50°C in 4x SSC or at 40°C in 6x SSC and 50% formamide, followed by washing at 50°C in 2x SSC. The length of the hybrid is the anticipated length for the hybridising nucleic acid. When nucleic acids of known sequence are hybridised, the hybrid length may be determined by aligning the sequences and identifying the conserved regions described herein. 1 xSSC is 0.15M NaCI and 15mM sodium citrate; the hybridisation solution and wash solutions may additionally include 5x Denhardt's reagent, 0.5-1.0% SDS, 100 pg/ml denatured, fragmented salmon sperm DNA, 0.5% sodium pyrophosphate. Another example of high stringency conditions is hybridisation at 65°C in 0.1x SSC comprising 0.1 SDS and optionally 5x Denhardt's reagent, 100 pg/ml denatured, fragmented salmon sperm DNA, 0.5% sodium pyrophosphate, followed by the washing at 65°C in 0.3x SSC.
For the purposes of defining the level of stringency, reference can be made to Sambrook et al. (2001) Molecular Cloning: a laboratory manual, 3rd Edition, Cold Spring Harbor Laboratory Press, CSH, New York or to Current Protocols in Molecular Biology, John Wiley & Sons, N.Y. (1989 and yearly updates).
Any number of methods well known to those skilled in the art can be used to isolate and manipulate a polynucleotide, or fragment thereof, as disclosed herein. For example, polymerase chain reaction (PCR) technology can be used to amplify a particular starting polynucleotide molecule and/or to produce variants of the original molecule. Polynucleotide molecules, or fragment thereof, can also be obtained by other techniques, such as by directly synthesizing the fragment by chemical means, as is commonly practiced by using an automated oligonucleotide synthesizer. A polynucleotide can be single-stranded (ss) or double- stranded (ds). "Double-stranded" refers to the base-pairing that occurs between sufficiently complementary, anti-parallel nucleic acid strands to form a double-stranded nucleic acid structure, generally under physiologically relevant conditions. Embodiments of the method include those wherein the polynucleotide is at least one selected from the group consisting of sense single- stranded DNA (ssDNA), sense single-stranded RNA (ssRNA), double-stranded RNA (dsRNA), double-stranded DNA (dsDNA), a double-stranded DNA/RNA hybrid, anti- sense ssDNA, or anti-sense ssRNA; a mixture of polynucleotides of any of these types can be used.
In a further aspect of the invention, provided is the method for increasing or conferring fungal resistance in a plant or plant material, comprising the steps of 1) stably transforming a plant cell with at least one expression cassette comprising an exogenous nucleic acid encoding a SIGRP1 protein as defined in the invention, 2) regenerating a plant from the plant cell; and 3) expressing the said the SIGRP1 protein. The method for increasing or conferring fungal resistance in a plant or plant material according to the invention, wherein the fungal resistance is against at least one biotrophic or heminecrotrophic fungus, preferably against a rust fungus.
According to the invention any suitable or standard transformation method can be used in step 1). As used herein, the terms "cassette", "plasmid", and "vector" refer to an extra-chromosomal element often carrying genes that are not part of the native genome of the cell, and usually in the form of double-stranded DNA. Such elements may be autonomously replicating sequences, genome integrating sequences, phage, or nucleotide sequences, in linear or circular form, of a single- or double-stranded DNA or RNA, derived from any source, in which a number of nucleotide sequences have been joined or recombined into a unique construction which is capable of introducing a polynucleotide of interest into a cell. As used herein, the term "expression" refers to the production of a functional end-product (e.g., DNA, gene, mRNA, guide R A, or a protein) in either precursor or mature form. Any expression cassette suitable can be applied according to the invention. The term "expression cassette" is synonymous with the term "nucleic acid construct" when the nucleic acid construct contains the control sequences required for expression of a polynucleotide.
In an further aspect of the invention, provided is a method for production of a genetically modified plant or plant material having increased fungal resistance compared to a respective wild-type plant or wild-type plant material, comprising the steps of 1) introducing an exogenous nucleic acid encoding a SIGRP1 protein into a plant or plant material; 2) generating a genetically modified plant or genetically modified plant material; and 3) expressing a SIGRP1 protein in the genetically modified plant or genetically modified plant material, wherein the SIGRP1 protein is encoded as described in the invention.
As used herein, a "genetically modified organism/plant" (GMO) is an organism whose genetic characteristics contain alteration(s) that were produced by human effort causing transfection that results in transformation of a target organism with genetic material from another or "source" organism, or with synthetic or modified-native genetic material, or an organism that is a descendant thereof that retains the inserted genetic material. The source organism can be of a different type of organism (e.g., a GMO plant can contain bacterial genetic material) or from the same type of organism (e.g., a GMO plant can contain genetic material from another plant).
As used herein, the term "endogenous", "native", or "original" refers to a naturally- occurring nucleic acid or polypeptide/protein. The native nucleic acid or protein may have been physically derived from a particular organism in which it is naturally occurring or may be a synthetically constructed nucleic acid or protein that is identical to the naturally-occurring nucleic acid or protein. The term "transgenic" refers to an organism, preferably a plant or part thereof, or a nucleic acid that comprises a heterologous polynucleotide. Preferably, the heterologous polynucleotide is stably integrated within the genome such that the polynucleotide is passed on to successive generations. The heterologous polynucleotide may be integrated into the genome alone or as part of a recombinant expression cassette. "Transgenic" is used herein to refer to any cell, cell line, callus, tissue, plant part or plant, the genotype of which has been so altered by the presence of heterologous nucleic acid including those transgenic organisms or cells initially so altered, as well as those created by crosses or asexual propagation from the initial transgenic organism or cell. A "recombinant" organism preferably is a "transgenic" organism. The term "transgenic" as used herein is not intended to encompass the alteration of the genome (chromosomal or extra-chromosomal) by conventional plant breeding methods (e.g., crosses) or by naturally occurring events such as, e.g., self-fertilization, random cross-fertilization, nonrecombinant viral infection, non-recombinant bacterial transformation, non- recombinant transposition, or spontaneous mutation.
As used herein, "mutagenized" refers to an organism or nucleic acid thereof having alteration(s) in the biomolecular sequence of its native genetic material as compared to the sequence of the genetic material of a corresponding wildtype organism or nucleic acid, wherein the alteration(s) in genetic material were induced and/or selected by human action. Examples of human action that can be used to produce a mutagenized organism or DNA include, but are not limited to treatment with a chemical mutagen such as EMS and subsequent selection with herbicide(s); or by treatment of plant cells with x-rays and subsequent selection with herbicide(s). Any method known in the art can be used to induce mutations. Methods of inducing mutations can induce mutations in random positions in the genetic material or can induce mutations in specific locations in the genetic material (i.e. , can be directed mutagenesis techniques), such as by use of a genoplasty technique. In addition to unspecific mutations, according to the invention a nucleic acid can also be mutagenized by using mutagenesis means with a preference or even specificity for a particular site, thereby creating an artificially induced heritable allele according to the present invention. Such means, for example site specific nucleases, including for example zinc finger nucleases (ZFNs), meganucleases, transcription activator- 1 ike effector nucelases (TALENS) (Malzahn et al., Cell Biosci, 2017, 7:21) and clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease (CRISPR/Cas) with an engineered crRNA/tracr RNA (for example as a single-guide RNA, or as modified crRNA and tracrRNA molecules which form a dual molecule guide), and methods of using this nucleases to target known genomic locations, are well-known in the art (see reviews by Bortesi and Fischer, 2015, Biotechnology Advances 33: 41-52; and by Chen and Gao, 2014, Plant Cell Rep 33: 575-583, and references within).
The invention also provides a method for production of a genetically modified plant or plant material having increased fungal resistance according to the invention, further comprising the steps of harvesting the seeds of the transgenic plant and planting the seeds and growing the seeds to plants, wherein the grown plants comprise anyone of the exogenous nucleic acid as described in the invention.
The term "seed" comprises seeds of all types, such as, for example, true seeds, caryopses, achenes, fruits, tubers, seedlings and similar forms. Preferably "seed" refers to true seed(s) unless otherwise specified. For example, the seed can be seed of transgenic plants or plants obtained by site specific mutagenesis, by mutagenesis with a site preference or by traditional breeding methods. Examples of traditional breeding methods are cross-breeding, selfing, back-crossing, embryo rescue, in-crossing, out-crossing, inbreeding, selection, asexual propagation, and other traditional techniques as are known in the art.
The present invention provides a plant or plant material having increased fungal resistance, wherein the plant or plant material comprises increased production and/or accumulation of a SIGRP1 protein in comparison to a respective wild-type plant or plant material, wherein the said plant or plant material is selected from the group consisting of members of the taxonomic family Fabaceae, Brassicaceae and Poaceae, preferably of family Fabaceae, and more preferably of genus Glycine.
The plant or the plant material is preferably selected from the group consisting of members of the taxonomic family Fabaceae, Brassicaceae and Poaceae’, preferably family Fabaceae, and more preferably subfamily Faboideae, preferably of taxonomic tribus Phaseoleae, more preferably of genus Cajanus, Canavalia, Glycine, Phaseolus, Psophocarpus, Pueraria or Vigna, even more preferably of species Cajanus cajan, Canavalia brasiliensis, Canavalia ensiformis, Canavalia gladiata, Glycine gracilis, Glycine max, Glycine soja, Phaseolus acutifolius, Phaseolus lunatus, Phaseolus maculatus, Psophocarpus tetragonolobus, Pueraria montana, Vigna angularis, Vigna mungo, Vigna radiata or Vigna unguiculata, even more preferably of species Glycine gracilis, Glycine max or Glycine soja, even more preferably of species Glycine max, taxonomic tribus Fabeae, more preferably of genus Lathyrus, Lens, Pisum or Vicia, even more preferably of species Lathyrus aphaca, Lathyrus cicera, Lathyrus hirsutus, Lathyrus ochrus, Lathyrus odoratus, Lathyrus sphaericus, Lathyrus tingitanus, Lens culinaris, Pisum sativum, Vicia cracca, Vicia faba or Vicia vellosa, taxonomic tribus Brassiceae, more preferably of genus Brassica, Crambe, Raphanus or Sinapis, even more preferably of species Brassica aucheri, Brassica balearica, Brassica barrelieri, Brassica bourgeaui, Brassica carinata, Brassica cretica, Brassica deflexa, Brassica desnottesii, Brassica drepanensis, Brassica elongata, Brassica fruticulosa, Brassica gravinae, Brassica hilarionis, Brassica incana, Brassica insularis, Brassica juncea, Brassica macrocarpa, Brassica maurorum, Brassica montana, Brassica napus, Brassica nigra, Brassica oleracea, Brassica oxyrrhina, Brassica procumbens, Brassica rapa, Brassica repanda, Brassica rupestris, Brassica souliei, Brassica spinescens, Brassica tournefortii, Brassica villosa or crosses of any of these species, even more preferably Brassica napus (rape), Brassica nigra (black mustard), Brassica oleracea (wild cabbage), Brassica rapa (field mustard) or crosses of any of these species, even more preferably Brassica napus species Raphanus sativus, species Sinapis alba, taxonomic tribus Andropogoneae, Bambuseae, Oryzeae, Poeae, Triticeae, more preferably of genus Saccharum, Zea, Oryza, Avena, Hordeum, Secale, Triticum, even more preferably of species Zea mays, Oryza sativa, Avena sativa, Avena strigosa, Hordeum marinum, Hordeum vulgare, Secale cereale or Triticum aestivum,
The plant is preferably a crop plant, more preferably a plant of tribus Phaseoleae, even more preferably of genus Amphicarpaea, Cajanus, Canavalia, Dioclea, Erythrina, Glycine, Arachis, Lathyrus, Lens, Pisum, Vicia, Vigna, Phaseolus or Psophocarpus, even more preferably of species Amphicarpaea bracteata, Cajanus cajan, Canavalia brasiliensis, Canavalia ensiformis, Canavalia gladiata, Dioclea grandi flora, Erythrina latissima, Phaseolus acutifolius, Phaseolus lunatus, Phaseolus maculatus, Psophocarpus tetragonolobus, Vigna angularis, Vigna mungo, Vigna unguiculata, Glycine albicans, Glycine aphyonota, Glycine arenaria, Glycine argyrea, Glycine canescens, Glycine clandestina, Glycine curvata, Glycine cyrtoloba, Glycine dolichocarpa, Glycine falcata, Glycine gracei, Glycine hirticaulis, Glycine lactovirens, Glycine latifolia, Glycine latrobeana, Glycine microphylla, Glycine peratosa, Glycine pindanica, Glycine pullenii, Glycine rubiginosa, Glycine stenophita, Glycine syndetika, Glycine tabacina, Glycine tomentella, Glycine gracilis, Glycine max, Glycine max x Glycine soja, Glycine soja, more preferably of species Glycine gracilis, Glycine max, Glycine max x Glycine soja, Glycine soja, most preferably of soybean. It is a particular advantage of the present invention that the invention provides material and methods to improve resistance of such plants against fungal pathogens, particularly rust pathogens like Phakopsora, which in these plants are difficult to manage using fungicides and which cause severe losses of plant yield and harvest material quality.
The present invention in particular provides materials, preferably plants, plant parts or plant cells, or methods to increase fungal resistance. According to the invention, increase of fungal resistance is achieved preferably by reducing, compared to a corresponding wild type, the speed of infection or the extent of infection or delaying the day of earliest infection by the fungus. Thus, the SIGRP1 protein and gene of the present invention is suitable for conferring, intensifying or stabilizing resistance of plants, plant parts or plant cells against fungal pathogen infections, particularly against biotrophic, hemibiotrophic or heminecrotrophic fungi, and preferably against fungi as described herein.
The present invention is particularly useful for fighting against a plant pathogenic fungus. According to the invention the fungus to fight against is preferably a biotrophic, hemibiotrophic or heminecrotrophic fungus, more preferably a rust fungus, downy mildew, powdery mildew, leaf spot, late blight, fusarium and/or Septoria, and is even more preferably selected from the taxonomic phylum Basidiomycota, more preferably the taxonomic class Pucciniomycetes, more preferably the taxonomic class Pucciniales, more preferably the taxonomic class family Pucciniaceae, more preferably the taxonomic class genus Puccinia, more preferably the taxonomic class species Puccinia graminis', or phylum Basidiomycota, more preferably the taxonomic class Pucciniomycetes, more preferably the taxonomic class order Pucciniales, more preferably the taxonomic class family Phakopsoraceae, more preferably the taxonomic class genus Phakopsora, more preferably the taxonomic class species Phakopsora pachyrhizi or Phakopsora meibomiae', or phylum Ascomycota, more preferably the taxonomic class class Sordariomycetes, more preferably the taxonomic class order Hypocreales, more preferably the taxonomic class family Nectriaceae, more preferably the taxonomic class genus Fusarium, more preferably the taxonomic class species Fusarium graminearum or Fusarium verticillioides.
According to the invention, the plant or the plant material having increased fungal resistance, wherein the increased fungal resistance is against a rust fungus, preferably against a fungus or a fungus-like organism selected from the phyla Ascomycota, Basisiomycota or Oomycota. Preferably from phylum Basidiomycota, more preferably of subphylum Pucciniomycotina, even more preferably of class Pucciniomycetes, even more preferably of order Pucciniales, much more preferably of family Araucariomycetaceae, Chaconiaceae, Coleosporiaceae, Cronartiaceae, Crossopsoraceae, Gymnosporangiaceae, Melampsoraceae, Milesinaceae, Ochropsoraceae, Phakopsoraceae, Phragmidiaceae, Pileolariaceae, Pucciniaceae, Pucciniosiraceae, Pucciniastraceae, Raveneliaceae, Rogerpetersoniaceae, Skierkaceae, Sphaerophragmiaceae, Tranzscheliaceae, Uropyxidaceae, Zaghouaniaceae, mitosporic Pucciniales and incertae sedis, even more preferably of genus Maravalia, Ochropsora, Olivea, Chrysomyxa, Coleosporium, Diaphanopellis, Cronartium, Endocronartium, Peridermium, Melampsora, Chrysocelis, Mikronegeria, Arthuria, Batistopsora, Cerotelium, Dasturella, Phakopsora, Prospodium, Arthuriomyces, Catenulopsora, Gerwasia, Gymnoconia, Hamaspora, Kuehneola, Phragmidium, Trachyspora, Triphragmium, Atelocauda, Pileolaria, Racospermyces, Uromycladium, Allodus, Ceratocoma, Chrysocyclus, Cumminsiella, Cystopsora, Endophyllum, Gymnosporangium, Miyagia, Puccinia, Puccorchidium, Roestelia, Sphenorchidium, Stereostratum, Uromyces, Hyalopsora, Melampsorella, Melampsoridium, Milesia, Milesina, Naohidemyces, Pucciniastrum, Thekopsora, Uredinopsis, Chardoniella, Dietelia, Pucciniosira, Diorchidium, Endoraecium, Kernkampella, Ravenelia, Sphenospora, Austropuccinia, Nyssopsora, Sphaerophragmium, Dasyspora, Leucotelium, Macruropyxis, Porotenus, Tranzschelia or Uropyxis, much more preferably of species Rhizoctonia alpina, Rhizoctonia bicornis, Rhizoctonia butinii, Rhizoctonia callae, Rhizoctonia carotae, Rhizoctonia endophytica, Rhizoctonia floccosa, Rhizoctonia fragariae, Rhizoctonia fraxini, Rhizoctonia fusispora, Rhizoctonia globularis, Rhizoctonia gossypii, Rhizoctonia muneratii, Rhizoctonia papayae, Rhizoctonia quercus, Rhizoctonia repens, Rhizoctonia rubi, Rhizoctonia Silvestris, Rhizoctonia solani, Phakopsora ampelopsidis, Phakopsora apoda, Phakopsora argentinensis, Phakopsora cherimoliae, Phakopsora cingens, Phakopsora coca, Phakopsora crotonis, Phakopsora euvitis, Phakopsora gossypii, Phakopsora hornotina, Phakopsora jatrophicola, Phakopsora meibomiae, Phakopsora meliosmae, Phakopsora meliosmae-myrianthae, Phakopsora montana, Phakopsora muscadiniae, Phakopsora myrtacearum, Phakopsora nishidana, Phakopsora orientalis, Phakopsora pachyrhizi, Phakopsora phyllanthi, Phakopsora tecta, Phakopsora uva, Phakopsora vitis, Phakopsora ziziphi-vulgaris, Puccinia abrupta, Puccinia acetosae, Puccinia achnatheri-sibirici, Puccinia acroptili, Puccinia actaeae-agropyri, Puccinia actaeae-elymi, Puccinia antirrhini, Puccinia argentata, Puccinia arrhenatheri, Puccinia arrhenathericola, Puccinia artemisiae-keiskeanae, Puccinia arthrocnemi, Puccinia asteris, Puccinia atra, Puccinia aucta, Puccinia ballotiflora, Puccinia bartholomaei, Puccinia bistortae, Puccinia cacabata, Puccinia calcitrapae, Puccinia calthae, Puccinia calthicola, Puccinia calystegiae-soldanellae, Puccinia canaliculata, Puccinia caricis-montanae, Puccinia caricis- stipatae, Puccinia carthami, Puccinia cerinthes-agropyrina, Puccinia cesatii, Puccinia chrysanthemi, Puccinia circumdata, Puccinia clavata, Puccinia coleataeniae, Puccinia coronata, Puccinia coronati-agrostidis, Puccinia coronati-brevispora, Puccinia coronati- calamagrostidis, Puccinia coronati-hordei, Puccinia coronati-japonica, Puccinia coronati- longispora, Puccinia crotonopsidis, Puccinia cynodontis, Puccinia dactylidina, Puccinia dietelii, Puccinia digitata, Puccinia distincta, Puccinia duthiae, Puccinia emaculata, Puccinia erianthi, Puccinia eupatoriicolumbiani, Puccinia flavenscentis, Puccinia gastrolobii, Puccinia geitonoplesii, Puccinia gigantea, Puccinia glechomatis, Puccinia helianthi, Puccinia heterogenea, Puccinia heterospora, Puccinia hydrocotyles, Puccinia hysterium, Puccinia impatientis, Puccinia impedita, Puccinia imposita, Puccinia infra-aequatorialis, Puccinia insolita, Puccinia justiciae, Puccinia klugkistiana, Puccinia knersvlaktensis, Puccinia lantanae, Puccinia lateritia, Puccinia latimamma, Puccinia liberta, Puccinia littoralis, Puccinia lobata, Puccinia lophatheri, Puccinia loranthicola, Puccinia menthae, Puccinia mesembryanthemi, Puccinia meyeri-albertii, Puccinia miscanthi, Puccinia miscanthidii, Puccinia mixta, Puccinia montanensis, Puccinia morata, Puccinia morthieri, Puccinia nitida, Puccinia oenanthes- stoloniferae, Puccinia operta, Puccinia otzeniani, Puccinia patriniae, Puccinia pentstemonis, Puccinia persistens, Puccinia phyllostachydis, Puccinia pittieriana, Puccinia platyspora, Puccinia pritzeliana, Puccinia prostii, Puccinia pseudodigitata, Puccinia pseudostriiformis, Puccinia psychotriae, Puccinia punctata, Puccinia punctiformis, Puccinia recondita, Puccinia rhei-undulati, Puccinia rupestris, Puccinia senecionis-acutiformis, Puccinia septentrionalis, Puccinia setariae, Puccinia silvatica, Puccinia stipina, Puccinia stobaeae, Puccinia striiformis, Puccinia striiformoides, Puccinia stylidii, Puccinia substriata, Puccinia suzutake, Puccinia taeniatheri, Puccinia tageticola, Puccinia tanaceti, Puccinia tatarinovii, Puccinia tetragoniae, Puccinia thaliae, Puccinia thlaspeos, Puccinia tillandsiae, Puccinia tiritea, Puccinia tokyensis, Puccinia trebouxi, Puccinia triticina, Puccinia tubulosa, Puccinia tulipae, Puccinia tumidipes, Puccinia turgida, Puccinia urticae-acutae, Puccinia urticae-acutiformis, Puccinia urticae- caricis, Puccinia urticae-hirtae, Puccinia urticae-inflatae, Puccinia urticata, Puccinia vaginatae, Puccinia virgata, Puccinia xanthii, Puccinia xanthosiae, Puccinia zoysiae, more preferably of species Phakopsora pachyrhizi, Puccinia graminis, Puccinia striiformis, Puccinia hordei or Puccinia recondita, more preferably of genus Phakopsora and most preferably Phakopsora pachyrhizi.
As indicated above, fungi of these taxa are responsible for grave losses of crop yield. This applies in particular to rust fungi of genus Phakopsora. It is thus an advantage of the present invention that the method allows to reduce fungicide treatments against Phrakopsora pachyrhizi as described herein. It is a particularly preferable advantage that the materials and methods of the present invention are useful for fighting against rust fungi of genus Phakopsora, in particular and most preferred against Phakopsora pachyrhizi, Phakopsora meibomiae, Puccinia graminis, Puccinia striiformis, Puccinia hordei or Puccinia recondite, and combination of these species. These fungal pathogens are responsible for huge losses of soybean when soybean plants are left untreated. The present invention thus allows to reduce the number of fungicide treatments by reducing the fungal pathogen pressure. According to the invention, it is possible that increasing the production and/or accumulation of SIGRP1 protein in the plant or plant material results in reducing more than one specific fungal pathogen pressure, namely the combination of any of the above-mentioned fungi.
The invention further provides a recombinant vector construct comprising a nucleic acid encoding a SIGRP1 protein selected from the group consisting of: i) an exogenous nucleic acid encoding a protein having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with SEQ ID NO. 1 , 3, 5, 7, 9, 11 , 13, 15, 17, 19, and 21 , or a functional fragment thereof; or ii) an exogenous nucleic acid having at least 70% identity, preferably at least 80% identity, more preferably at least 90% identity, and much more preferably at least 95% identity with any of the SEQ ID NO. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 22, or a functional fragment thereof or a splice variant thereof; or iii) an exogenous nucleic acid capable of hybridizing under stringent conditions with a complementary sequence of any of the nucleic acids according to i) or ii); or iv) an exogenous nucleic acid encoding the same SIGRP1 protein as the nucleic acids of i) to iii) above, but differing from the nucleic acids of i) to iii) above due to the degeneracy of the genetic code. In the recombinant expression vector, the promoter is a constitutive, pathogen-inducible promoter, a mesophyll-specific promoter or an epidermis specific-promoter. As used herein, "recombinant" when referring to nucleic acid or polypeptide, indicates that such material has been altered as a result of human application of a recombinant technique, such as by polynucleotide restriction and ligation, by polynucleotide overlap-extension, or by genomic insertion or transformation. A gene sequence open reading frame is recombinant if (a) that nucleotide sequence is present in a context other than its natural one, for example by virtue of being (i) cloned into any type of artificial nucleic acid vector or (ii) moved or copied to another location of the original genome, or if (b) the nucleotide sequence is mutagenized such that it differs from the wild type sequence. The term recombinant also can refer to an organism having a recombinant material, e.g., a plant that comprises a recombinant nucleic acid is a recombinant plant.
In one aspect, the recombinant expression vector is a constitutive, pathogen-inducible promoter, a mesophyll-specific promoter or an epidermis specific-promoter. In another aspect, a genetically modified plant or genetically modified plant material, transformed with at least one of the recombinant vector constructs according to the aspects above. The promoter preferably is a constitutive, pathogen-inducible promoter, a mesophyll-specific promoter or an epidermis specific-promoter. The selection of any of these promoters allows to produce, in a plant cell, a respectively constitutively increased level of SIGRP1 protein, or an increased level in response to a pathogen infection, preferably a fungal pathogen, or to increase the level of SIGRP1 protein specifically in mesophyll or plant epidermis cells.
The invention further provides the use of a SIGRP1 protein or a nucleic acid encoding the SIGRP1 protein to increase fungal resistance in a plant, preferably wherein the increase of fungal resistance comprises the delay or reduced infection of a plant by a fungus. The nucleic acid can be an isolated DNA molecule. As used herein, the term "isolated DNA molecule" refers to a DNA molecule at least partially separated from other molecules normally associated with it in its native or natural state. The term "isolated" preferably refers to a DNA molecule that is at least partially separated from some of the nucleic acids which normally flank the DNA molecule in its native or natural state. Thus, DNA molecules fused to regulatory or coding sequences with which they are not normally associated, for example as the result of recombinant techniques, are considered isolated herein. Such molecules are considered isolated when integrated into the chromosome of a host cell or present in a nucleic acid solution with other DNA molecules, in that they are not in their native state. The protein can be expressed and isolated or chemically synthesized, purified or impurified, folded or unfolded polypeptides and protein molecules.
The present invention further provides a method of controlling a fungus in a field, preferably by reducing or delaying infection of plant in a field and/or reducing or delaying emission of fungal spores from the field, comprising the step of 1) planting seed from any of the plants according to the invention, and/or optionally, one or more active agents including fungicide can be applied to the plants, by such as spraying or splashing.
According to the invention, one or more active agents that can be employed to further reduce pathogen caused infections. The active agents may be any agent, preferably a chemical agent, that produces a desired effect on the plant or plant material. Non-limiting examples of such chemical agents include pesticides (such as fungicides, acaricides, miticides, insecticides, insect repellents, rodenticides, molluscicides, nematicides, bactericides, and fumigants), herbicides, chemical hybridizing agents, auxins, antibiotics and other drugs, biological attractants, growth regulators, pheromones and dyes. Specific non-limiting examples of chemical agents useful as active ingredients include triticonazole, imidacloprid, tefluthrin, and silthiophenamide (N-allyl-4,5-dimethyl-2-trimethylsilylthiophene-3-caboxamide). Further active agents suitable for use in the present invention are, for example, phytochemicals and antimicrobial agents suitable to protect soybean. Preferred examples thereof are bactericides, antiparasitics and fungicides. The fungicides are for instance selected from the group of classes consisting of strobilurins, triazoles, carboxamides, penflufen, isopyrazam, bixafen, sedaxane, and fluxapyroxad, and mixtures thereof.
By increasing fungal resistance as described herein, the SIGP1 protein and gene of the present invention are suitable to reduce the number of fungicide treatments required to protect growing plants. The invention thus also provides a farming method, comprising the step of applying at least one less fungicide treatment to plants than would be required for wild-type control plants grown under the same conditions. For example, in Brazil it may be customary to apply a first fungicide treatment to soybean plants on day 8 after seeding and a second spray on day 18 after seeding. In other regions a scheme may be practiced not depending on mere time of growth but, for example, taking into account first notice of a pest occurrence or passing of a pest incidence threshold. It is a particular and unforeseen advantage of the present invention that the number of pesticide treatments per growth seasons can be reduced compared to a control plant. It was in particular surprising that such treatment reduction is possible not only without reducing yield; instead the farming method according to the invention advantageously allows to maintain or even increase yield despite the reduction in treatments. This greatly improves cost efficiency of farming the plants as provided by the present invention. Of course, the pesticide is preferably applied in pesticidal effective amounts.
According to the invention the pest is or comprises at least a biotrophic or heminecrotrophic fungus, more preferably a rust fungus. If during cultivation the plant is also under threat of stress by other pathogens, e.g. nematodes and insects, such other pests are preferably taken care of by respective pesticide treatments. Thus, according to the invention preferably the number of fungicide treatments is reduced as described above, irrespective of other pesticide treatments. The fungicide can be mixed with other pesticides and ingredients preferably selected from insecticides, nematicides, and acaricides, herbicides, plant growth regulators, fertilizers. Preferred mixing partners are insecticides, nematicides and fungicides. It is particularly preferred to reduce, during cultivation of the plant, the number of fungicide treatments per growth season by at least one relative to the control plant, preferably by at least two. Fungicides may include 2-(thiocyanatomethylthio)-benzothiazole, 2-phenylphenol, 8- hydroxyquinoline sulfate, ametoctradin, amisulbrom, antimycin, Ampelomyces quisqualis, azaconazole, azoxystrobin, Bacillus subtilis, Bacillus subtilis strain QST713, benalaxyl, benomyl, benthiavalicarb-isopropyl, benzylaminobenzene- sulfonate (BABS) salt, bicarbonates, biphenyl, bismerthiazol, bitertanol, bixafen, blasticidin-S, borax, Bordeaux mixture, boscalid, bromuconazole, bupirimate, calcium polysulfide, captafol, captan, carbendazim, carboxin, carpropamid, carvone, chlazafenone, chloroneb, chlorothalonil, chlozolinate, Coniothyrium minitans, copper hydroxide, copper octanoate, copper oxychloride, copper sulfate, copper sulfate (tribasic), cuprous oxide, cyazofamid, cyflufenamid, cymoxanil, cyproconazole, cyprodinil, dazomet, debacarb, diammonium ethylenebis-(dithiocarbamate), dichlofluanid, dichlorophen, diclocymet, diclomezine, dichloran, diethofencarb, difenoconazole, difenzoquat ion, diflumetorim, dimethomorph, dimoxystrobin, diniconazole, diniconazole-M, dinobuton, dinocap, diphenylamine, dithianon, dodemorph, dodemorph acetate, dodine, dodine free base, edifenphos, enestrobin, enestroburin, epoxiconazole, ethaboxam, ethoxyquin, etridiazole, famoxadone, fenamidone, fenarimol, fenbuconazole, fenfuram, fenhexamid, fenoxanil, fenpiclonil, fenpropidin, fenpropimorph, fenpyrazamine, fentin, fentin acetate, fentin hydroxide, ferbam, ferimzone, fluazinam, fludioxonil, fluindapyr, flumorph, fluopicolide, fluopyram, fluoroimide, fluoxastrobin, fluquinconazole, flusilazole, flusulfamide, flutianil, flutolanil, flutriafol, fluxapyroxad, folpet, formaldehyde, fosetyl, fosetyl- aluminium, fuberidazole, furalaxyl, furametpyr, guazatine, guazatine acetates, GY-81 , hexachlorobenzene, hexaconazole, hymexazol, imazalil, imazalil sulfate, imibenconazole, iminoctadine, iminoctadine triacetate, iminoctadine tris(albesilate), iodocarb, ipconazole, ipfenpyrazolone, iprobenfos, iprodione, iprovalicarb, isoprothiolane, isofetamide, isopyrazam, isotianil, kasugamycin, kasugamycin hydrochloride hydrate, kresoxim-methyl, laminarin, mancopper, mancozeb, mandipropamid, maneb, mefenoxam, mepanipyrim, mepronil, meptyldinocap, mercuric chloride, mercuric oxide, mercurous chloride, metalaxyl, metalaxyl- M, metam, metam- ammonium, metam-potassium, metam-sodium, metconazole, methasulfocarb, methyl iodide, methyl isothiocyanate, metiram, metominostrobin, metrafenone, mildiomycin, myclobutanil, nabam, nitrothal-isopropyl, nuarimol, octhilinone, ofurace, oleic acid (fatty acids), orysastrobin, oxadixyl, oxathiapiprolin, oxine-copper, oxpoconazole fumarate, oxycarboxin, pefurazoate, penconazole, pencycuron, penflufen, pentachlorophenol, pentachlorophenyl laurate, penthiopyrad, phenylmercury acetate, phosphonic acid, phthalide, picoxystrobin, polyoxin B, polyoxins, polyoxorim, potassium bicarbonate, potassium hydroxyquinoline sulfate, probenazole, prochloraz, procymidone, propamocarb, propamocarb hydrochloride, propiconazole, propineb, proquinazid, pydiflumetofen, prothioconazole, pyraclostrobin, pyrametostrobin, pyraoxystrobin, pyraziflumid, pyrazophos, pyribencarb, pyributicarb, pyrifenox, pyrimethanil, pyriofenone, pyroquilon, quinoclamine, quinoxyfen, quintozene, Reynoutria sachalinensis extract, sedaxane, silthiofam, simeconazole, sodium 2-phenylphenoxide, sodium bicarbonate, sodium pentachlorophenoxide, spiroxamine, sulfur, SYP-Z048, tar oils, tebuconazole, tebufloquin, tecnazene, tetraconazole, thiabendazole, thifluzamide, thiophanate-methyl, thiram, tiadinil, tolclofos-methyl, tolylfluanid, triadimefon, triadimenol, triazoxide, tricyclazole, tridemorph, trifloxystrobin, triflumizole, triforine, triticonazole, validamycin, valifenalate, valiphenal, vinclozolin, zineb, ziram, zoxamide, Candida oleophila, Fusarium oxysporum, Gliocladium spp., Phlebiopsis gigantea, Streptomyces griseoviridis, Trichoderma spp., (RS)-N-(3,5- dichlorophenyl)-2-(methoxymethyl)-succinimide, 1 ,2-dichloropropane, 1 ,3-dichloro-l , 1, 3, 3- tetrafluoroacetone hydrate, 1-chloro-2,4-dinitronaphthalene, 1-chloro-2-nitropropane, 2-(2- heptadecyl-2-imidazolin-1-yl)ethanol, 2,3-dihydro-5-phenyl-l,4-dithi-ine 1 ,1,4,4-tetraoxide, 2- methoxyethylmercury acetate, 2-methoxyethylmercury chloride, 2-methoxyethylmercury silicate, 3-(4-chlorophenyl)-5-methylrhodanine, 4-(2-nitroprop- l-enyl)phenyl thiocyanateme, aminopyrifen, ampropylfos, anilazine, azithiram, barium polysulfide, Bayer 32394, benodanil, benquinox, bentaluron, benzamacril; benzamacril-isobutyl, benzamorf, benzovindiflupyr, binapacryl, bis(methylmercury)sulfate, bis(tributyltin) oxide, buthiobate, cadmium calcium copper zinc chromate sulfate, carbamorph, CECA, chlobenthiazone, chloraniformethan, chlorfenazole, chlorquinox, climbazole, copper bis(3-phenylsalicylate), copper zinc chromate, coumoxystrobin, cufraneb, cupric hydrazinium sulfate, cuprobam, cyclafuramid, cypendazole, cyprofuram, decafentin, dichlobentiazox, dichlone, dichlozoline, diclobutrazol, dimethirimol, dinocton, dinosulfon, dinoterbon, dipymetitrone, dipyrithione, ditalimfos, dodicin, drazoxolon, EBP, enoxastrobin, ESBP, etaconazole, etem, ethirim, fenaminosulf, fenaminstrobin, fenapanil, fenitropan, fenpicoxamid, fluindapyr, fluopimomide, fluotrimazole, flufenoxystrobin, furcarbanil, furconazole, furconazole-cis, furmecyclox, furophanate, glyodine, griseofulvin, halacrinate, Hercules 3944, hexylthiofos, ICIA0858, inpyrfluxam, ipfentrifluconazole, ipflufenoquin, isofetamid, isoflucypram, isopamphos, isovaledione, mandestrobin, mebenil, mecarbinzid, mefentrifluconazole, metazoxolon, methfuroxam, methylmercury dicyandiamide, metsulfovax, metyltetraprole, milneb, mucochloric anhydride, myclozolin, N-3,5- dichlorophenyl-succinimide, N-3-nitrophenylitaconimide, natamycin, N-ethylmercurio-4- toluenesulfonanilide, nickel bis(dimethyldithiocarbamate), OCH, oxathiapiprolin, phenylmercury dimethyldithiocarbamate, phenylmercury nitrate, phosdiphen, picarbutrazox, prothiocarb; prothiocarb hydrochloride, pydiflumetofen, pyracarbolid, pyrapropoyne, pyraziflumid, pyridachlometyl, pyridinitril, pyrisoxazole, pyroxychlor, pyroxyfur, quinacetol, quinacetol sulfate, quinazamid, quinconazole, quinofumelin, rabenzazole, salicylanilide, SSF- 109, sultropen, tecoram, thiadifluor, thicyofen, thiochlorfenphim, thiophanate, thioquinox, tioxymid, triamiphos, triarimol, triazbutil, trichlamide, triclopyricarb, triflumezopyrim, urbacid, zarilamid, and any combinations thereof.
The plant, plant material or plant cell may comprise, in addition to the heterologous SIGP1 gene, one or more further heterologous elements. For example, transgenic soybean events comprising herbicide tolerance genes are for example, but not excluding others, GTS 40-3-2, MON87705, MON87708, MON87712, MON87769, MON89788, A2704-12, A2704-21 , A5547- 127, A5547-35, DP356043, DAS44406-6, DAS68416-4, DAS-81419-2, GU262, SYHT0H2, W62, W98, FG72 and CV127; transgenic soybean events comprising genes for insecticidal proteins are for example, but not excluding others, MON87701 , MON87751 and DAS-81419. Cultivated plants comprising a modified oil content have been created by using the transgenes: gm-fad2-1 , Pj.D6D, Nc.Fad3, fad2-1A and fatb1-A. Examples of soybean events comprising at least one of these genes are: 260-05, MON87705 and MON87769. Plants comprising such singular or stacked traits as well as the genes and events providing these traits are well known in the art. For example, detailed information as to the mutagenized or integrated genes and the respective events are available from websites of the organizations International Service for the Acquisition of Agri. Biotech Applications (ISAAA) (http://www.isaaa.org/gmapprovaldatabase) and the Center for Environmental Risk Assessment (CERA) (http://cera-qmc.org/GMCropDatabase). Further information on specific events and methods to detect them can be found for soybean events H7-1 , MON89788, A2704-12, A5547-127, DP305423, DP356043, MON87701 , MON87769, CV127, MON87705, DAS68416-4, MON87708, MON87712, SYHT0H2, DAS81419, DAS81419 x DAS44406-6, MON87751 in WO04/074492, W006/130436, WO06/108674, WO06/108675, WO08/054747, W008/002872, WO09/064652, WG09/102873, W010/080829, W010/037016, W011/066384, W011/034704, WO12/051199, WO12/082548, W013/016527, WO13/016516, WO14/201235.
In addition to fungicides, the plant, plant material or plant cell may also be treated with one ore more biopesticides. It is an advantage of the present invention that the SIGP1 gene does not interfere with the beneficial effects of biopesticides. Many biopesticides have been deposited under deposition numbers mentioned herein (the prefices such as ATCC or DSM refer to the acronym of the respective culture collection, for details see e. g. here: htp://www. wfcc.info/ccinfo/collection/by_acronym/), are referred to in literature, registered and/or are commercially available: mixtures of Aureobasidium pullulans DSM 14940 and DSM 14941 isolated in 1989 in Konstanz, Germany (e. g. blastospores in Blossom Protect® from bio-ferm GmbH, Austria), Azospirillum brasilense Sp245 originally isolated in wheat reagion of South Brazil (Passo Fundo) at least prior to 1980 (BR 11005; e. g. GELFIX® Gramineas from BASF Agricultural Specialties Ltd., Brazil), A. brasilense strains Ab-V5 and Ab-V6 (e. g. in AzoMax from Novozymes BioAg Produtos papra Agricultura Ltda., Quattro Barras, Brazil or Simbiose- Maiz® from Simbiose-Agro, Brazil; Plant Soil 331 , 413-425, 2010), Bacillus amyloliquefaciens strain AP-188 (NRRL B-50615 and B-50331 ; US 8,445,255); B. amyloliquefaciens spp. plantarum D747 isolated from air in Kikugawashi, Japan (US 20130236522 A1 ; FERM BP 8234; e. g. Double Nickel™ 55 WDG from Certis LLC, USA), B. amyloliquefaciens spp. plantarum FZB24 isolated from soil in Brandenburg, Germany (also called SB3615; DSM 96- 2; J. Plant Dis. Prot. 105, 181-197, 1998; e. g. Taegro® from Novozyme Biologicals, Inc., USA), B. amyloliquefaciens ssp. plantarum FZB42 isolated from soil in Brandenburg, Germany (DSM 23117; J. Plant Dis. Prot. 105, 181-197, 1998; e. g. RhizoVital® 42 from AbiTEP GmbH, Germany), B. amyloliquefaciens ssp. plantarum MBI600 isolated from faba bean in Sutton Bonington, Nottinghamshire, U.K. at least before 1988 (also called 1430; NRRL B 50595; US 2012/0149571 A1 ; e. g. Integral® from BASF Corp., USA), B. amyloliquefaciens spp. plantarum QST-713 isolated from peach orchard in 1995 in California, U.S.A. (NRRL B 21661 ; e. g. Serenade® MAX from Bayer Crop Science LP, USA), B. amyloliquefaciens spp. plantarum TJ1000 isolated in 1992 in South Dakoda, U.S.A, (also called 1 BE; ATCC BAA-390; CA 2471555 A1 ; e. g. QuickRoots™ from TJ Technologies, Watertown, SD, USA), B. firmus CNCM 1-1582, a variant of parental strain EIP-N1 (CNCM 1-1556) isolated from soil of central plain area of Israel (WO 2009/126473, US 6,406,690; e. g. Votivo® from Bayer CropScience LP, USA), B. pumilus GHA 180 isolated from apple tree rhizosphere in Mexico (IDAC 260707- 01 ; e. g. PRO-MIX® BX from Premier Horticulture, Quebec, Canada), B. pumilus INR-7 otherwise referred to as BU F22 and BU-F33 isolated at least before 1993 from cucumber infested by Erwinia tracheiphila (NRRL B-50185, NRRL B-50153; US8,445,255), (NRRL B- 50754; WO 2014/029697; B. pumilus QST 2808 was isolated from soil collected in Pohnpei, Federated States of Micronesia, in 1998 (NRRL B 30087; e. g. Sonata® or Ballad® Plus from Bayer Crop Science LP, USA), B. simplex ABU 288 (NRRL B-50304; US8,445,255), B. subtilis FB17 also called UD 1022 or UD10-22 isolated from red beet roots in North America (ATCC PTA-11857; System. Appl. Microbiol. 27, 372-379, 2004; US 2010/0260735; WO 2011/109395); B. thuringiensis ssp. aizawai ABTS-1857 isolated from soil taken from a lawn in Ephraim, Wisconsin, U.S.A., in 1987 (also called ABG 6346; ATCC SD-1372; e. g. XenTari® from BioFa AG, Munsingen, Germany), B. t. ssp. kurstaki ABTS-351 identical to HD-1 isolated in 1967 from diseased Pink Bollworm black larvae in Brownsville, Texas, U.S.A. (ATCC SD- 1275; e. g. Dipel® DF from Valent BioSciences, IL, USA), B. t. ssp. kurstaki SB4 isolated from E. saccharina larval cadavers (NRRL B-50753; B. t. ssp. tenebrionis NB-176-1 , a mutant of strain NB-125, a wild type strain isolated in 1982 from a dead pupa of the beetle Tenebrio molitor (DSM 5480; EP585215 B1 ; e. g. Novodor® from Valent BioSciences, Switzerland), Beauveria bassiana GHA (ATCC 74250; e. g. BotaniGard® 22WGP from Laverlam Int. Corp., USA), B. bassiana JW-1 (ATCC 74040; e. g. Naturalis® from CBC (Europe) S.r.l., Italy), B. bassiana PPRI 5339 isolated from the larva of the tortoise beetle Conchyloctenia punctata (NRRL 50757), Bradyrhizobium elkanii strains SEMIA 5019 (also called 29W) isolated in Rio de Janeiro, Brazil and SEMIA 587 isolated in 1967 in the State of Rio Grande do Sul, from an area previously inoculated with a North American isolate, and used in commercial inoculants since 1968 (Appl. Environ. Microbiol. 35 73(8), 2635, 2007; e. g. GELFIX 5 from BASF Agricultural Specialties Ltd., Brazil), B. japonicum 532c isolated from Wisconsin field in U.S.A. (Nitragin 61A152; Can. J. Plant. Sci. 70, 661-666, 1990; e. g. in Rhizoflo®, Histick®, Hicoat® Super from BASF Agricultural Specialties Ltd., Canada), B. japonicum E-109 variant of strain USDA 138 (INTA E109, SEMIA 5085; Eur. J. Soil Biol. 45, 28-35, 2009; Biol. Fertil. Soils 47, 81-89, 2011); B. japonicum strains deposited at SEMIA known from Appl. Environ. Microbiol. 73(8), 2635, 2007: SEMIA 5079 isolated from soil in Cerrados region, Brazil by Embrapa- Cerrados used in commercial inoculants since 1992 (CPAC15; e. g. GELFIX 5 or ADHERE 60 from BASF Agricultural Specialties Ltd., Brazil), B. japonicum SEMIA 5080 obtained under lab condtions by Embrapa-Cerrados in Brazil and used in commercial inoculants since 1992, being a natural variant of SEMIA 586 (CB1809) originally isolated in U.S.A. (CPAC 7; e. g. GELFIX 5 or AD-HERE 60 from BASF Agricultural Specialties Ltd., Brazil); Burkholderia sp. A396 isolated from soil in Nikko, Japan, in 2008 (NRRL B-50319; WO 2013/032693; Marrone Bio Innovations, Inc., USA), Coniothyrium minitans CON/M/91-08 isolated from oilseed rape (WO 1996/021358; DSM 9660; e. g. Contans® WG, Intercept® WG from Bayer CropScience AG, Germany), harpin (alpha-beta) protein (Science 257, 85-88, 1992; e. g. Messenger™ or HARP-N Tek from Plant Health Care pic, U.K.), Helicoverpa armigera nucleopolyhedrovirus (HearNPV) (J. Invertebrate Pathol. 107, 112-126, 2011 ; e. g. Helicovex® from Adermatt Biocontrol, Switzerland; Diplomata® from Koppert, Brazil; Vivus® Max from AgBiTech Pty Ltd., Queensland, Australia), Helicoverpa zea single capsid nucleopolyhedrovirus (HzSNPV) (e. g. Gemstar® from Certis LLC, USA), Helicoverpa zea nucleopolyhedrovirus ABA-NPV-U (e. g. Heligen® from AgBiTech Pty Ltd., Queensland, Australia), Heterorhabditis bacteriophora (e. g. Nemasys® G from BASF Agricultural Specialities Limited, UK), Isaria fumosorosea Apopka- 97 isolated from mealy bug on gynura in Apopka, Florida, U.S.A. (ATCC 20874; Biocontrol Science Technol. 22(7), 747-761 , 2012; e. g. PFR-97™ or PreFeRal® from Certis LLC, USA), Metarhizium anisopliae var. anisopliae F52 also called 275 or V275 isolated from codling moth in Austria (DSM 3884, ATCC 90448; e. g. Met52® Novozymes Biologicals Bio-Ag Group, Canada), Metschnikowia fructicola 277 isolated from grapes in the central part of Israel (US 6,994,849; NRRL Y-30752; e. g. formerly Shemer® from Agrogreen, Israel), Paecilomyces ilacinus 251 isolated from infected nematode eggs in the Philippines (AGAL10 89/030550; WQ1991/02051 ; Crop Protection 27, 352-361 , 2008; e. g. BioAct®from Bayer CropScience AG, Germany and MeloCon® from Certis, USA), Pasteuria nishizawae Pn1 isolated from a soybean field in the mid-2000s in Illinois, U.S.A. (ATCC SD 5833; Federal Register 76(22), 5808, February 2, 2011 ; e.g. Clariva™ PN from Syngenta Crop Protection, LLC, USA), Penicillium bilaiae (also called P. bilaii) strains ATCC 18309 (= ATCC 74319), ATCC 20851 and/or ATCC 22348 (= ATCC 74318) originally isolated from soil in Alberta, Canada (Fertilizer Res. 39, 97-103, 1994; Can. J. Plant Sci. 78(1), 91-102, 1998; US 5,026,417, WO 1995/017806; e.g. Jump Start®, Provide® from Novozymes Biologicals BioAg Group, Canada), Reynoutria sachalinensis extract (EP 0307510 B1 ; e. g. Regalia® SC from Marrone BioInnovations, Davis, CA, USA or Milsana® from BioFa AG, Germany), Steinernema carpocapsae (e. g. Millenium® from BASF Agricultural Specialities Limited, UK), S. feltiae (e. g. Nemashield® from BioWorks, Inc., USA; Nemasys® from BASF Agricultural Specialities Limited, UK), Streptomyces microflavus NRRL B-50550 (WO 2014/124369; Bayer CropScience, Germany), T. harzianum T- 22 also called KRL-AG2 (ATCC 20847; Bio-Control 57, 687-696, 2012; e. g. Plantshield® from BioWorks Inc., USA or SabrEx™ from Advanced Biological Marketing Inc., Van Wert, OH, USA).
The invention also provides a method for evaluating the fungal resistance of the plant comprising the step of at least one step for detecting presence of a heterologous SIGRP1 gene or protein expression level in a plant material. The molecular marker for selection of the plant or plant material comprising nucleic acid for detecting SIGRP1 in a plant material, wherein the nucleic acid is selected from the group consisting of 1) primer sequence of the SIGRP1 protein having the SEQ ID NO. 23 or SEQ ID NO. 24, or 2) probe sequence of the SIGRP1 protein having the SEQ ID NO. 25.
In another aspect, the invention covers the use of the molecular maker for selecting a plant or a plant material having SIGRP1 protein induced fungal resistance.
The invention further provides harvestable part of a plant as described, wherein the harvestable part of the plant comprises an exogenous nucleic acid encoding the SIGRP1 protein, wherein the harvestable part is a seed of the plant, preferably genetically modified seed of the genetically modified plant.
In another aspect, the invention provides dead and/or non-propagative plant material derived from a plant as described or from the harvestable part of the plant according to the invention, wherein the dead and/or non-propagative plant material comprises the exogenous nucleic acid encoding the SIGRP1 protein.
According to a further aspect of the invention, provided is product derived from a plant described or from the harvestable part of the plant according to the invention, wherein the product comprises the exogenous nucleic acid encoding the SIGRP1 protein as defined, wherein the product is preferably a soy product, more preferably soybeans, soy oil or soy meal.
“Soy product” refers composition of soybean, product derived from soybean, product made of by soybeans, soybean composition including but not limited to 1) soy oil, for instance comprising no trans-fat, low in saturated fat, monounsaturated oleate, polyunsaturated linoleate, polyunsaturated linolenate. 2) dietary fibers, for instance comprising complex polysaccharides cellulose, hemicelluloses, and pectin. 3) Isoflavone, 4) anthocyanin, 5) vitamins A, B6, B12, C, and K, or combination thereof.
Soy products are non-fermented and fermented foods, including but not limited to soymilk, tofu, soy sauce, miso, Chungkookjang/Cheonggukjang, Doenjang, fermented bean curd/Chinese cheese/ pickled tofu/ sufu/tao-hu-yi/fu-su/, fu-zu/, to-fu-zu Gochujang, In shi, tau si, douche, Natto, Sweet bean sauce/Tianmianjiang, Tauco, Tempeh, Thua-nao, Tuong, soybased infant formula, meat and dairy substitutes, animal feeds,
Soybeans are also commercialized in many industrial products including oils, soap, cosmetics, resins, plastics, inks, crayons, solvents, and clothing, fiber-rich materials including desalted shoyu mash residue, alcohol-insoluble solid, and water-insoluble solid were prepared from shoyu mash residue, which is a filtration cake obtained during the isolation of shoyu by press filtration of fermented matrix in the final process.
The present invention also provides use of the plant for modifying genetic variation in a plant population.
As used herein, the term “genetic variation” is used as known in the art. As further guidance, and without limitation, genetic variability or genetic variation may refer to the presence or generation of genetic differences (between individuals or within a population) or the formation of individuals differing in genotype, or the presence of genotypically different individuals (in a population). In one aspect of the invention, provided is a method for breeding a fungal resistant crop plant comprising 1) crossing the plant according to the invention, or the plant obtainable by the method of the invention with a second plant; 2) obtaining seed from the cross of step 1); 3) planting said seeds and growing the seeds to plants; and 4) selecting from said descendant plants expressing the SIGRP1 protein as described.
As used herein, "descendant" refers to any generation plant. A progeny or descendant plant can be from any filial generation, e.g., F1 , F2, F3, F4, F5, F6, F7, etc. In some embodiments, a descendant or progeny plant is a first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth generation plant.
The invention further provides a method for producing a plant or plant material having increased pathogen resistance comprising introducing the SIGRP1 protein encoded as described using genome editing, preferably using a CRISPR system.
The terms "genome editing", "gene editing", and "genome engineering" are used interchangeably herein and refer to strategies and techniques for the targeted, specific modification of any genetic information or genome of a living organism (e.g., soybean) at least one position. As such, the terms comprise gene editing, but also the editing of regions other than gene encoding regions of a genome.
Genome editing may comprise targeted or non-targeted (random) mutagenesis. Targeted mutagenesis may be accomplished for instance with designer nucleases, such as for instance with meganucleases, zinc finger nucleases (ZFNs), transcription activator-like effector-based nucleases (TALEN), and the clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) system. These nucleases create site-specific double-strand breaks (DSBs) at desired locations in the genome. The induced double-strand breaks are repaired through nonhomologous end-joining (NHEJ) or homologous recombination (HR), resulting in targeted mutations or nucleic acid modifications. The use of designer nucleases is particularly suitable for generating gene knockouts or knockdowns. In certain embodiments, designer nucleases are developed which specifically induce a mutation in the SIGRP1 gene, as described herein elsewhere, such as to generate a mutated SIGRP1 protein or a knockout of the SIGRP1 gene. In certain aspects, designer nucleases, in particular RNA-specific CRISPR/Cas systems are developed which specifically target the SIGRP1 mRNA, such as to cleave the SIGRP1 mRNA and generate a knockdown of the SIGRP1 gene/mRNA/protein. Delivery and expression systems of designer nuclease systems are well known in the art.
The CRISPR (clustered regularly interspaced short palindromic repeats) technology may be used to modify the genome of a target organism, for example to introduce any given DNA fragment into nearly any site of the genome, to replace parts of the genome with desired sequences or to precisely delete a given region in the genome of a target organism. This allows for unprecedented precision of genome manipulation.
The CRISPR system was initially identified as an adaptive defense mechanisms of bacteria belonging to the genus of Streptococcus (W02007/025097). Those bacterial CRISPR systems rely on guide RNA (gRNA) in complex with cleaving proteins to direct degradation of complementary sequences present within invading viral DNA. The application of CRISPR systems for genetic manipulation in various eukaryotic organisms have been shown (W02013/141680; WO2013/176772; WO2014/093595). Cas9, the first identified protein of the CRISPR/Cas system, is a large monomeric DNA nuclease guided to a DNA target sequence adjacent to the PAM (protospacer adjacent motif) sequence motif by a complex of two noncoding RNAs: CRSIPR RNA (crRNA) and trans-activating crRNA (tracrRNA). Also a synthetic RNA chimera (single guide RNA or sgRNA) created by fusing crRNA with tracrRNA was shown to be equally functional (WO2013/176772). CRISPR systems from other sources comprising DNA nucleases distinct from Cas9 such as Cpf1 , C2c1p or C2c3p have been described having the same functionality (WO2016/0205711 , WO2016/205749). Other authors describe systems in which the nuclease is guided by a DNA molecule instead of an RNA molecule. Such system is for example the AGO system as disclosed in LIS2016/0046963.
Several research groups have found that the CRISPR cutting properties could be used to disrupt target regions in almost any organism’s genome with unprecedented ease. Recently it became clear that providing a template for repair allows for editing the genome with nearly any desired sequence at nearly any site, transforming CRISPR into a powerful gene editing tool (WO2014/150624, WO2014/204728). The template for repair is addressed as donor nucleic acid comprising at the 3’ and 5’ end sequences complementary to the target region allowing for homologous recombination in the respective template after introduction of double strand breaks in the target nucleic acid by the respective nuclease.
The main limitation in choosing the target region in a given genome is the necessity of the presence of a PAM sequence motif close to the region where the CRISPR related nuclease introduces double strand breaks. However, various CRISPR systems recognize different PAM sequence motifs. This allows choosing the most suitable CRISPR system for a respective target region. Moreover, the AGO system does not require a PAM sequence motif at all.
The technology may for example be applied for alteration of gene expression in any organism, for example by exchanging the promoter upstream of a target gene with a promoter of different strength or specificity. Other methods disclosed in the prior art describe the fusion of activating or repressing transcription factors to a nuclease minus CRISPR nuclease protein. Such fusion proteins may be expressed in a target organism together with one or more guide nucleic acids guiding the transcription factor moiety of the fusion protein to any desired promoter in the target organism (WO2014/099744; WO2014/099750). Knockouts of genes may easily be achieved by introducing point mutations or deletions into the respective target gene, for example by inducing non-homologous-end-joining (NHEJ) which usually leads to gene disruption (WO2013/176772).
Thus, the invention also provides an ensemble of at least 50 crop plants according to the present invention, more preferably at least 100 plants, even more preferably at least 1000 plants, even more preferably at least 100000 plants. According to the invention, preferably at least 100000 plants are grown per hectar, more preferably 200000 to 800000 plants per hectar, even more preferably at least 250000 to 650000 plants per hectar. Such plant numbers preferably are observed within one hectar; thus, the invention particularly facilitates ecologically considerate intensive farming with reduced use of fungicides per growing season. The plants according to the invention are preferably growing in a field or greenhouse. Preferably the crop plants are soy plants. According to the invention it is not required that all crop plants of one species growing in the same field or greenhouse are plants of the present invention. Instead, it is sufficient in monoculture plantation if at least about 25% of the plants of one species belong to the present invention, more preferably at least 50%, even more preferably 25%-75% and most preferably 45%-70%, especially when mixed or combined with plants harboring other resistance genes or mechanisms. The combination with plants with other resistance gene can be done by interplanting (mixing), row-wise or blockwise. For example, on a soybean field it is possible to reduce the number of fungicide treatments if approximately every second plant is a plant according to the present invention. It is particularly preferred that at least 25%, more preferably 50%-100% and even more preferably 75%-100% of those plants on the same field that are not plants according to the present invention comprise at least one other biological means for enhancing fungal resistance, most preferably the other means is selected from the list of pathogen resistance polypeptides as described above.
It is a particular advantage of the present invention that expression of a SIGRP1 protein of the present invention for improving fungal resistance can be combined with any of the aforementioned further genes for conferring hypoallergenicity and/or low content of antinutrients. This was all the more surprising since it is known that in soybean gene silencing is a major factor contributing to spontaneous decrease of gene expression when two individually effective genes are combined, for example by crossing or co-transformation, into one plant's genetic material.
EXAMPLES
Example 1 : General methods
The chemical synthesis of oligonucleotides can be affected, for example, in the known fashion using the phosphoamidite method (Voet, Voet, 2nd Edition, Wiley Press New York, pages 896- 897). The cloning steps carried out for the purposes of the present invention such as, for example, restriction cleavages, agarose gel electrophoresis, purification of DNA fragments, transfer of nucleic acids to nitrocellulose and nylon membranes, linking DNA fragments, transformation of E. coli cells, bacterial cultures, phage multiplication and sequence analysis of recombinant DNA, are carried out as described by Sambrook et al. Cold Spring Harbor Laboratory Press (1989), ISBN 0-87969-309-6. The sequencing of recombinant DNA molecules is carried out with an MWG-Licor laser fluorescence DNA sequencer following the method of Sanger (Sanger et al., Proc. Natl. Acad. Sci. USA 74, 5463 (1977).
Example 2: Cloning of SIGRP1 for plant transformation
The cDNA sequence of SIGRP1 gene mentioned in this application was generated by DNA synthesis (Geneart, Regensburg, Germany).
The constitutively expressed SIGRP1 construct was generated as follows:
The SIGRP1 gene (for instance, as shown in SEQ ID NO. 2) was synthesized in a way that a Asci restriction site is located in front of the start-ATG and a Sbfl restriction site downstream of the stop-codon. The synthesized DNA was digested using the restriction enzymes Sbfl and Asci (NEB Biolabs) and ligated in a Sbfl/Ascl digested Gateway pENTRY-B vector (Invitrogen, Life Technologies, Carlsbad, California, USA) in a way that the full-length fragment is located in sense direction between the parsley ubiquitin promoter and the Agrobacterium tumefaciens derived nopaline synthase terminator (t-nons). The Pcllbi promoter regulates constitutive expression of the ubi4-2 gene (accession number X64345) of Petroselinum crispum (Kawalleck et al. 1993 Plant Molecular Biology 21(4): 673 - 684).
To obtain the binary plant transformation vector, a triple LR reaction (Gateway system, Invitrogen, Life Technologies, Carlsbad, California, USA) was performed according to manufacturer’s protocol by using an empty pENTRY-A vector, the PcUbi promoter:: SIGRP1 :nos1 terminator in the above described pENTRY-B vector and an empty pENTRY-C. As target a binary pDEST vector was used which is composed of: (1) a Kanamycin resistance cassette for bacterial selection (2) a pVS1 origin for replication in Agrobacteria (3) a ColE1 origin of replication for stable maintenance in E. coli and (4) between the right and left border an AHAS selection under control of its endogenous AtAHAS promoter and t-AtAHAS terminator. The recombination reaction was transformed into E. coli (DH5alpha), mini-prepped and screened by specific restriction digestions. A positive clone from each vector construct was sequenced and submitted soy transformation.
Example 3: Soybean transformation
The expression vector constructs (see example 2) is transformed into soybean.
3.1 Sterilization and Germination of Soybean Seeds
Virtually any seed of any soybean variety can be employed in the method of the invention. A variety of soybean cultivar (including Jack, Williams 82, Jake, Stoddard, CD215 and Resnik) is appropriate for soybean transformation. Soybean seeds are sterilized in a chamber with a chlorine gas produced by adding 3.5 ml 12N HCI drop wise into 100 ml bleach (5.25% sodium hypochlorite) in a desiccator with a tightly fitting lid. After 24 to 48 hours in the chamber, seeds are removed and approximately 18 to 20 seeds are plated on solid GM medium with or without 5 pM 6-benzyl-aminopurine (BAP) in 100 mm Petri dishes. Seedlings without BAP are more elongated and roots develop especially secondary and lateral root formation. BAP strengthens the seedling by forming a shorter and stockier seedling.
Seven-day-old seedlings grown in the light (>100 p Einstein/m2s) at 25 °C are used for explant material for the three-explant types. At this time, the seed coat was split, and the epicotyl with the unifoliate leaves are grown to, at minimum, the length of the cotyledons. The epicotyl should be at least 0.5 cm to avoid the cotyledonary-node tissue (since soybean cultivars and seed lots may vary in the developmental time a description of the germination stage is more accurate than a specific germination time).
For inoculation of entire seedlings, see Method A (example 3.3. and 3.3.2) or leaf explants see Method B (example 3.3.3).
For method C (see example 3.3.4), the hypocotyl and one and a half or part of both cotyledons are removed from each seedling. The seedlings are then placed on propagation media for 2 to 4 weeks. The seedlings produce several branched shoots to obtain explants from. The majority of the explants originated from the plantlet growing from the apical bud. These explants are preferably used as target tissue. 3.2 Growth and Preparation of Agrobacterium Culture
Agrobacterium cultures are prepared by streaking Agrobacterium (e.g., A. tumefaciens or A. rhizogenes) carrying the desired binary vector (e.g. H. Klee. R. Horsch and S. Rogers 1987 Agrobacterium-Mediated Plant Transformation and its further Applications to Plant Biology; Annual Review of Plant Physiology Vol. 38: 467-486) onto solid YEP growth medium YEP media: 10 g yeast extract. 10 g Bacto Peptone. 5 g NaCI. Adjust pH to 7.0, and bring final volume to 1 litre with H2O, for YEP agar plates add 20g Agar, autoclave) and incubating at 25°C. until colonies appeared (about 2 days). Depending on the selectable marker genes present on the Ti or Ri plasmid, the binary vector, and the bacterial chromosomes, different selection compounds are to be used for A. tumefaciens and A. rhizogenes selection in the YEP solid and liquid media. Various Agrobacterium strains can be used for the transformation method.
After approximately two days, a single colony (with a sterile toothpick) is picked and 50 ml of liquid YEP is inoculated with antibiotics and shaken at 175 rpm (25 °C) until an OD600 between 0.8-1.0 is reached (approximately 2 d). Working glycerol stocks (15%) for transformation are prepared and one-ml of Agrobacterium stock aliquoted into 1.5 ml Eppendorf tubes then stored at -80 °C.
The day before explant inoculation, 200 ml of YEP are inoculated with 5 pl to 3 ml of working Agrobacterium stock in a 500 ml Erlenmeyer flask. The flask is shaken overnight at 25 °C. until the OD600 is between 0.8 and 1.0. Before preparing the soybean explants, the Agrobacteria ARE pelleted by centrifugation for 10 min at 5,500 x g at 20 °C. The pellet is suspended in liquid CCM to the desired density (OD600 0.5-0.8) and placed at room temperature at least 30 min before use.
3.3 Explant Preparation and Co-Cultivation (Inoculation)
3.3.1 Method A:
Explant Preparation on the Day of Transformation. Seedlings at this time had elongated epicotyls from at least 0.5 cm but generally between 0.5 and 2 cm. Elongated epicotyls up to 4 cm in length are successfully employed. Explants are then prepared with: i) with or without some roots, ii) with a partial, one or both cotyledons, all preformed leaves are removed including apical meristem, and the node located at the first set of leaves is injured with several cuts using a sharp scalpel.
This cutting at the node not only induces Agrobacterium infection but also distributes the axillary meristem cells and damaged pre-formed shoots. After wounding and preparation, the explants are set aside in a Petri dish and subsequently co-cultivated with the liquid CCM/Agrobacterium mixture for 30 minutes. The explants are then removed from the liquid medium and plated on top of a sterile filter paper on 15x100 mm Petri plates with solid cocultivation medium. The wounded target tissues are placed such that they are in direct contact with the medium.
3.3.2 Modified Method A: Epicotyl Explant Preparation
Soybean epicotyl segments prepared from 4 to 8 d old seedlings are used as explants for regeneration and transformation. Seeds of soybean are germinated in 1/10 MS salts or a similar composition medium with or without cytokinins for 4 to 8 d. Epicotyl explants are prepared by removing the cotyledonary node and stem node from the stem section. The epicotyl is cut into 2 to 5 segments. Especially preferred are segments attached to the primary or higher node comprising axillary meristematic tissue.
The explants are used for Agrobacterium infection. Agrobacterium AGL1 harbouring a plasmid with the gene of interest (GOI) and the AHAS, bar or dsdA selectable marker gene is cultured in LB medium with appropriate antibiotics overnight, harvested and suspended in an inoculation medium with acetosyringone. Freshly prepared epicotyl segments are soaked in the Agrobacterium suspension for 30 to 60 min and then the explants were blotted dry on sterile filter papers. The inoculated explants are then cultured on a co-culture medium with L- cysteine and TTD and other chemicals such as acetosyringone for increasing T-DNA delivery for 2 to 4 d. The infected epicotyl explants are then placed on a shoot induction medium with selection agents such as imazapyr (for AHAS gene), glufosinate (for bar gene), or D-serine (for dsdA gene). The regenerated shoots are sub-cultured on elongation medium with the selective agent.
For regeneration of transgenic plants, the segments are then cultured on a medium with cytokinins such as BAP, TDZ and/or Kinetin for shoot induction. After 4 to 8 weeks, the cultured tissues are transferred to a medium with lower concentration of cytokinin for shoot elongation. Elongated shoots are transferred to a medium with auxin for rooting and plant development. Multiple shoots are regenerated. Many stable transformed sectors showing strong cDNA expression are recovered. Soybean plants are regenerated from epicotyl explants. Efficient T- DNA delivery and stable transformed sectors are demonstrated.
3.3.3 Method B: Leaf Explants
For the preparation of the leaf explant the cotyledon is removed from the hypocotyl. The cotyledons are separated from another, and the epicotyl is removed. The primary leaves, which consist of the lamina, the petiole, and the stipules, are removed from the epicotyl by carefully cutting at the base of the stipules such that the axillary meristems are included on the explant. To wound the explant as well as to stimulate de novo shoot formation, any pre-formed shoots are removed and the area between the stipules was cut with a sharp scalpel 3 to 5 times. The explants are either completely immersed or the wounded petiole end dipped into the Agrobacterium suspension immediately after explant preparation. After inoculation, the explants are blotted onto sterile filter paper to remove excess Agrobacterium culture and place explants with the wounded side in contact with a round 7 cm Whatman paper overlaying the solid COM medium (see above). This filter paper prevents A. tumefaciens overgrowth on the soybean-explants. Wrap five plates with Parafilm. TM. "M" (American National Can, Chicago, III., USA) and incubate for three to five days in the dark or light at 25 °C.
3.3.4 Method C: Propagated Axillary Meristem
For the preparation of the propagated axillary meristem explant propagated 3-4 week-old plantlets are used. Axillary meristem explants can be pre-pared from the first to the fourth node. An average of three to four explants could be obtained from each seedling. The explants are prepared from plantlets by cutting 0.5 to 1.0 cm below the axillary node on the internode and removing the petiole and leaf from the explant. The tip where the axillary meristems lie is cut with a scalpel to induce de novo shoot growth and allow access of target cells to the Agrobacterium. Therefore, a 0.5 cm explant included the stem and a bud. Once cut, the explants are immediately placed in the Agrobacterium suspension for 20 to 30 minutes. After inoculation, the explants are blotted onto sterile filter paper to remove excess Agrobacterium culture then placed almost completely immersed in solid COM or on top of a round 7 cm filter paper overlaying the solid COM, depending on the Agrobacterium strain. This filter paper prevents Agrobacterium overgrowth on the soybean explants. Plates are wrapped with Parafilm.TM. "M" (American National Can, Chicago, III., USA) and incubated for two to three days in the dark at 25 °C.
3.4 Shoot Induction
After 3 to 5 days co-cultivation in the dark at 25 °C., the explants are rinsed in liquid SIM medium (to remove excess Agrobacterium) (SIM, see Olhoft et al 2007 A novel Agrobacterium rhizogenes-mediated transformation method of soybean using primary-node explants from seedlings In Vitro Cell. Dev. Biol. — Plant (2007) 43:536-549; to remove excess Agrobacterium) or Modwash medium (1X B5 major salts, 1X B5 minor salts, 1X MSI 11 iron, 3% Sucrose, 1X B5 vitamins, 30 mM MES, 350 mg/L Timentin pH 5.6, WO 2005/121345) and blotted dry on sterile filter paper (to prevent damage especially on the lamina) before placing on the solid SIM medium. The approximately 5 explants (Method A) or 10 to 20 (Methods B and C) explants are placed such that the target tissue was in direct contact with the medium. During the first 2 weeks, the explants could be cultured with or without selective medium. Preferably, explants are transferred onto SIM without selection for one week.
For leaf explants (Method B), the explant should be placed into the medium such that it is perpendicular to the surface of the medium with the petiole imbedded into the medium and the lamina out of the medium.
For propagated axillary meristem (Method C), the explant is placed into the medium such that it is parallel to the surface of the medium (basipetal) with the explant partially embedded into the medium.
Wrap plates with Scotch 394 venting tape (3M, St. Paul, Minn., USA) are placed in a growth chamber for two weeks with a temperature averaging 25°C. C. under 18 h light/6 h dark cycle at 70-100 pE/m2s. The explants remain on the SIM medium with or without selection until de novo shoot growth occurred at the target area (e.g., axillary meristems at the first node above the epicotyl). Transfers to fresh medium can occur during this time. Explants are transferred from the SIM with or without selection to SIM with selection after about one week. At this time, there is considerable de novo shoot development at the base of the petiole of the leaf explants in a variety of SIM (Method B), at the primary node for seedling explants (Method A), and at the axillary nodes of propagated explants (Method C).
Preferably, all shoots formed before transformation are removed up to 2 weeks after cocultivation to stimulate new growth from the meristems. This helped to reduce chimerism in the primary transformant and increase amplification of transgenic meristematic cells. During this time the explant may or may not be cut into smaller pieces (i.e. detaching the node from the explant by cutting the epicotyl). 3.5 Shoot Elongation
After 2 to 4 weeks (or until a mass of shoots is formed) on SIM medium (preferably with selection), the explants are transferred to SEM medium (shoot elongation medium, see Olhoft et al 2007 A novel Agrobacterium rhizogenes-mediated transformation method of soybean using primary-node explants from seedlings. In Vitro Cell. Dev. Biol. — Plant (2007) 43:536- 549) that stimulates shoot elongation of the shoot primordia. This medium may or may not contain a selection compound.
After every 2 to 3 weeks, the explants are transferred to fresh SEM medium (preferably containing selection) after carefully removing dead tissue. The explants should hold together and not fragment into pieces and retain somewhat healthy. The explants are continued to be transferred until the explant dies or shoots elongate. Elongated shoots >3 cm are removed and placed into RM medium for about 1 week (Methods A and B), or about 2 to 4 weeks depending on the cultivar (Method C) at which time roots began to form. In the case of explants with roots, they are transferred directly into soil. Rooted shoots are transferred to soil and hardened in a growth chamber for 2 to 3 weeks before transferring to the greenhouse. Regenerated plants obtained using this method are fertile and produced on average 500 seeds per plant.
After 5 days of co-cultivation with Agrobacterium tumefaciens transient expression of the gene of interest (GOI) is widespread on the seedling axillary meristem explants especially in the regions wounding during explant preparation (Method A). Explants are placed into shoot induction medium without selection to see how the primary-node responds to shoot induction and regeneration. Thus far, greater than 70% of the explants were formed new shoots at this region. Expression of the GOI is stable after 14 days on SIM, implying integration of the T-DNA into the soybean genome. In addition, preliminary experiments result in the formation of cDNA expressing shoots forming after 3 weeks on SIM.
For Method C, the average regeneration time of a soybean plantlet using the propagated axillary meristem protocol is 14 weeks from explant inoculation. Therefore, this method has a quick regeneration time that leads to fertile, healthy soybean plants.
Example 4 Pathogen assay for soybean
4.1. Growth of plants
12 T1 soybean plants per event and respective controls are potted and grown for 3-4 weeks in the phytochamber (16 h day- und 8 h-night-Rhythm at a temperature of 16 °C and 22 °C und a humidity of 75 %) till the first 2 trifoliate leaves were fully expanded.
4.2 Rating for plant health
A general rating of plant health is performed before (and partially after) the infection experiment. Only those plants are selected for inoculation that show, in general, a healthy phenotype. Healthy phenotype means normal growth habit, green, fully expanded green leaves, having no or only minor lesions, no obvious yellowing, leaf drop or other stress- associated phentotypes.
4.3 Inoculation The plants are inoculated with spores of P. pachyrhizi. In order to obtain appropriate spore material for the inoculation, soybean leaves, which are infected with rust 15-20 days ago, are taken 2-3 days before the inoculation and transferred to agar plates (1 % agar in H2O). The leaves are placed with their upper side onto the agar, which allowed the fungus to grow through the tissue and to produce very young spores. For the inoculation solution, the spores are knocked off the leaves and are added to a Tween-FhO solution. The counting of spores is performed under a light microscope by means of a Thoma counting chamber. For the inoculation of the plants, the spore suspension is added into a compressed-air operated spray flask and applied uniformly onto the plants or the leaves until the leaf surface is well moisturized. For macroscopic assays a spore density of 1-5x105 spores/ml is used. For the microscopy, a density of >5 x 105 spores I ml is used. The inoculated plants are placed for 24 hours in a greenhouse chamber with an average of 22°C and >90% of air humidity. The following cultivation is performed in a chamber with an average of 25°C and 70% of air humidity.
Microscopical evaluation
For the evaluation of the pathogen development, the inoculated leaves of plants are stained with aniline blue 48 hours after infection.
The aniline blue staining serves for the detection of fluorescent substances. During the defence reactions in host interactions and non-host interactions, substances such as phenols, callose or lignin accumulate or are produced and are incorporated at the cell wall either locally in papillae or in the whole cell (hypersensitive reaction, HR). Complexes are formed in association with aniline blue, which lead e.g. in the case of callose to yellow fluorescence. The leaf material is transferred to falcon tubes or dishes containing de-staining solution II (ethanol I acetic acid 6/1) and is incubated in a water bath at 90°C for 10-15 minutes. The de-staining solution II is removed immediately thereafter, and the leaves are washed 2x with water. For the staining, the leaves are incubated for 1.5-2 hours in staining solution II (0.05 % aniline blue = methyl blue, 0.067 M di-potassium hydrogen phosphate) and analysed by microscopy immediately thereafter.
The different interaction types are evaluated (counted) by microscopy. An Olympus UV microscope BX61 (incident light) and a UV Longpath filter (excitation: 375/15, Beam splitter: 405 LP) are used. After aniline blue staining, the spores appeared blue under UV light. The papillae can be recognized beneath the fungal appressorium by a green/yellow staining. The hypersensitive reaction (HR) is characterized by a whole cell fluorescence.
By rating and counting 50-200 individuals fungal-plant interaction sites on each transgenic and control leaves it can be observed that resistance inducing genes, show an increased number of defences associated fungal-plant interactions, such as papillae and hypersensitive reactions, whereas more susceptibility associated phenotypes, such as mycelial growth in the mesophyll, can by observed in control leaves.
Evaluating the susceptibility to soybean rust in greenhouse
The progression of the soybean rust disease is scored in percent by the estimation of the diseased area (area which was covered by sporulating uredinia) of a soybean leaf 14 days after inoculation (see above). Additionally, the yellowing of the leaf is taken into account. A scheme illustrating the disease rating can be found in Figure 1.
Up to 12 T1 soybean plants per event and 5 independent events per construct (55 plants in total) leading to the constitutive expression of the SIGRP1 protein plus 43 control plants (same genetic background) were inoculated with spores of Phakopsora pachyrhizi. The macroscopic disease symptoms of soybean against Phakopsora pachyrhizi of the inoculated soybean plants were scored by imaging 14 days after inoculation. The ratio of the leaf area showing fungal colonies or strong yellowing/browning on all leaves was considered as diseased leaf area. At all 55 T1 soybean plants (up to 12 plants per event and 5 independent events per construct) showing constitutive expression of the SIGRP1 protein were evaluated in parallel to 43 non- transgenic wild type control plants. Non-transgenic control plants are having the same genetic background compared to transgenics and the plants were grown in parallel to the transgenic plants in a fully randomized design. The constitutive expression of SIGRP1 by the construct described in example 2 leads to enhanced resistance of soybean against Phakopsora pachyrhizi in comparison to wild type control. As shown in Figure 4, on the left, the constitutive expression of SIGRP1 protein leads to an average reduction of the diseased leaf area from 11 ,8% in wild type (n=43) to 8,9%% in the transgenic plants (construct level; n=55), which represents an average increase of soybean rust resistance by 24,6%. This result is close to be statistically significant as a paired one sided Student’s t-test delivered a p-value of 0,056. This result qualified the SIGRP1 expressing construct to be tested in field trials (see below).
Example 7: Field trials
Homozygous T2 seeds were used for field trials. To obtain homozygous seeds, segregating T1 seeds of 3 events per construct were planted. Individual plants that were homozygous for the transgene were selected by using TaqMan® PCR assay as described by the manufacturer of the assay (Thermo Fisher Scientific, Waltham, MA USA 02451).
10-30 homozygous plants per event were grown under standard conditions (12 h daylength, 25°C) and selfed (in-bred). Mature homozygous seeds were harvested approx. 120 days after planting. Harvested seeds of all 10-30 homozygous plants per event were pooled.
Homozygous seeds of 3 events per construct were tested in the field for “real world” resistance against soybean rust. Field trials were performed in Brazil on two field sites close to Campinas (state of Sao Paulo) and close to Uberlandia (Minas Gerais). Those two sites are quite different in terms of environment and soybean rust disease pressure and disease progression.
Field trials were planted depending on weather conditions in November or early December to ensure inoculum of Asian soybean rust. Events were tested in split plot trials (2 m long, 4 rows per plot) and 3 replications per event, treatment and trial site. Soybean plants were cultivated using standard cultural practice, e.g. in terms of weed and insect control and fertilization. Concerning fungal disease control two treatment varieties were performed: 1. no fungicide treatment at all (“no treatment”) and 2. only one fungicide treatment at the onset of ASR disease (~35 - 40 days after planting), instead of 3-4 treatments over the season in standard agricultural practice. The 2 different treatment varieties were performed to increase variability of disease pressure and to prove robustness and stability of the resistance increasing effect. About 8-15 replicates per treatment and location were planted with control seeds. Depending on trial design the untransformed wild-type (WT) mother line or bulk of seeds harvested from null-segregants, grown in parallel to the transgenic mother plants (see above) were used as control.
Example 8: Soybean rust resistance in field trials
Soybean rust disease severity in field trials was rated by experts using the scheme published by Godoy et al (2006) (citation Godoy, C., Koga, L., Canteri, M. (2006) Diagrammatic scale for assessment of soybean rust severity, Fitopatologia Brasileira 31(1)).
In short, the three canopy levels (lower, middle and upper canopy) were rated independently and the average of the infection of all three canopy levels is counted as infection. At all 4-5 ratings were performed, starting at the early onset of disease and repeated mainly every 6- 10 days. If weather was not suitable for disease progression the time in between two ratings was elongated.
To eliminate transgene insertion effects, which would be only dependent on the integration locus, 3 independent transgenic events were planted per field trial.
To compare the overall disease severity in different events over the whole growing season we calculated the Area Under Disease Progression Curve (AUDPC) for each event, location and treatment (for reference see: M.J. Jeger and S.L.H. Viljanen-Rollinson (2001) The use of the area under the disease-progress curve (AUDPC) to assess quantitative disease resistance in crop cultivars Theor Appl Genet 102:32-40.).
To compare the soybean rust resistance across different treatments and sites the deltaAUDPC was calculated using the following formula:
DeltaAUDPC = AUDPC(event) - AUDPC(control)
If transgenic plots are more resistant to soybean rust, the AUDPC of the event plots will be smaller than the AUDPC of the control plots. Therefore, a negative deltaAUDPC indicates a higher resistance of the transgenic events.
The deltaAUDPC was calculated on event level (see figure 5, grey bars) and depicted for both locations and both treatments. The statistical significance of the result was calculated based on a 95% confidence level based on the least significant difference (LSD) calculated by a Dunnett's test.
It is clearly visible (in figure 5) that the constitutive expression of SIGRP1 leads to a significantly increased disease resistance against soybean rust disease under field conditions, corroborating the results obtained in greenhouse (see example 6).