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.2009 Jun 23;106(25):10343-7.
doi: 10.1073/pnas.0904209106. Epub 2009 Jun 8.

Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time

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Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time

Peter J Franks et al. Proc Natl Acad Sci U S A..

Abstract

Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO(2) between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO(2) (g(c(max))) to sites of assimilation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO(2), the crucial significance of similarly large variations in S has been overlooked. Here, we use physical diffusion theory to explain why large changes in S necessarily accompanied the changes in D and atmospheric CO(2) over the last 400 million years. In particular, we show that high densities of small stomata are the only way to attain the highest g(cmax) values required to counter CO(2)"starvation" at low atmospheric CO(2) concentrations. This explains cycles of increasing D and decreasing S evident in the fossil history of stomata under the CO(2) impoverished atmospheres of the Permo-Carboniferous and Cenozoic glaciations. The pattern was reversed under rising atmospheric CO(2) regimes. Selection for small S was crucial for attaining high g(cmax) under falling atmospheric CO(2) and, therefore, may represent a mechanism linking CO(2) and the increasing gas-exchange capacity of land plants over geologic time.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
The relationship between stomatal sizeS and densityD across the Phanerozoic. Each point is an individual species (seeTable S1). The curved line is the estimated upper theoretical limit to stomatal size at a given density, or the upper limit of density at a given size. All combinations of size and density must fall below this line. Diagrams in boxes are comparative representations of possible combinations of stomatal size and density to assist visualization of the scaling of these dimensions in real leaves.
Fig. 2.
Fig. 2.
Smaller stomata provide higher stomatal conductance for the same total pore area because of the shorter diffusion path length,l (see Eq.1). For any stomatal sizeS there is a theoretical maximum stomatal densityDmax based on simple geometric packing limitations. Here the total stomatal pore area per unit leaf area remains constant at the theoretical maximum for any given stomatal sizeS, but because that pore area is made up of ever-smaller and more numerous stomata, the stomatal conductance (gwmax) increases. SeeData and Methods for details.
Fig. 3.
Fig. 3.
For any givengwmax, smaller stomata free up more epidermal space for other cell types and functions. Shown are percentages of epidermal surface occupied by stomata as a function of variable stomatal sizeS for 3 fixed values ofgwmax. CO2-forcing of changes ingwmax via changes inS andD have implications for leaf attributes unrelated togwmax. SeeData and Methods for details.
Fig. 4.
Fig. 4.
Relationships between fossil stomatal traits and atmospheric CO2. Each point is the mean for either a 50- or 100-Myr time slice of the Phanerozoic, beginning at −400 Myr, or the mean for modern times (0 Myr). (A) Stomatal size is positively correlated with atmospheric CO2 concentration (y = 3.02x − 528;r2 = 0.92;P < 0.002). (B) Stomatal densityD decreases exponentially with atmospheric CO2 concentration, hence log10D is linearly correlated with CO2 (y = −0.000657x + 2.58;r2 = 0.98;P < 0.0001). (C) Maximum stomatal conductance to water vapor,gwmax, is negatively correlated with atmospheric CO2 concentration (y = −0.000441x + 1.29;r2 = 0.84;P < 0.006). (D)gwmax is negatively correlated with stomatal sizeS (y = −0.000124x + 1.15;r2 = 0.60;P = 0.04).
Fig. 5.
Fig. 5.
Distinct modes of stomatal trait evolution. Graduations ingwmax for multiple combinations ofS andD are represented by color contours. The curved black line represents the theoretical upper limit ofS versusD. Note thatgwmax at this limit increases withD, even thoughS decreases. Stomatal conductances attainable at smallS and highD are theoretically unattainable at much largerS and lowerD (red area), even though total pore area per unit leaf area is constant. Overlaid on this surface are data (pink symbols) forS andD from fossil plants, showing the predominance of smallerS and higherD in times of falling atmospheric CO2 concentration.
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References

    1. Farquhar GD, Sharkey TD. Stomatal conductance and photosynthesis. Annu Rev Plant Physiol. 1982;33:17–45.
    1. Hetherington AM, Woodward FI. The role of stomata in sensing and driving environmental change. Nature. 2003;424:901–908. - PubMed
    1. Edwards D, Kerp H, Hass H. Stomata in early land plants: an anatomical and ecophysiological approach. J Exp Bot. 1998;49:255–278.
    1. Raven JA. Selection pressures on stomatal evolution. New Phytol. 2002;153:371–386. - PubMed
    1. Franks PJ, Farquhar GD. The mechanical diversity of stomata and its significance in gas exchange control. Plant Physiol. 2007;143:78–87. - PMC - PubMed

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