Eyland David, van Wesemael Jelle, Lawson Tracy, Carpentier Sebastien
Division of Crop Biotechnics, Laboratory of Tropical Crop Improvement, KU Leuven, Leuven, Belgium.
School of Life Sciences, University of Essex, Colchester, Essex, UK.
Plant Physiol. 2021 Jun 11;186(2):998-1012. doi: 10.1093/plphys/kiab114.
Dynamic light conditions require continuous adjustments of stomatal aperture. The kinetics of stomatal conductance (gs) is hypothesized to be key to plant productivity and water use efficiency (WUE). Using step-changes in light intensity, we studied the diversity of light-induced gs kinetics in relation to stomatal anatomy in five banana genotypes (Musa spp.) and modeled the impact of both diffusional and biochemical limitations on photosynthesis (A). The dominant A limiting factor was the diffusional limitation associated with gs kinetics. All genotypes exhibited a strong limitation of A by gs, indicating a priority for water saving. Moreover, significant genotypic differences in gs kinetics and gs limitations of A were observed. For two contrasting genotypes, the impact of differential gs kinetics was further investigated under realistic diurnally fluctuating light conditions and at the whole-plant level. Genotype-specific stomatal kinetics observed at the leaf level was corroborated at whole-plant level by transpiration dynamics, validating that genotype-specific responses are still maintained despite differences in gs control at different locations in the leaf and across leaves. However, under diurnally fluctuating light conditions the impact of gs speediness on A and intrinsic (iWUE) depended on time of day. During the afternoon there was a setback in kinetics: absolute gs and gs responses to light were damped, strongly limiting A and impacting diurnal iWUE. We conclude the impact of differential gs kinetics depended on target light intensity, magnitude of change, gs prior to the change in light intensity, and particularly time of day.
动态光照条件要求气孔孔径不断调整。气孔导度（gs）的动力学被认为是植物生产力和水分利用效率（WUE）的关键。利用光强的阶跃变化，我们研究了五种香蕉基因型（芭蕉属）中光诱导的gs动力学与气孔解剖结构的关系，并模拟了扩散和生化限制对光合作用（A）的影响。主要的A限制因素是与gs动力学相关的扩散限制。所有基因型的A都受到gs的强烈限制，表明节水具有优先性。此外，还观察到gs动力学和A的gs限制存在显著的基因型差异。对于两种对比基因型，在实际的昼夜波动光照条件下和整株水平上进一步研究了不同gs动力学的影响。在叶片水平观察到的基因型特异性气孔动力学在整株水平上通过蒸腾动力学得到了证实，验证了尽管叶片不同位置和不同叶片的gs控制存在差异，但基因型特异性反应仍然得以维持。然而，在昼夜波动光照条件下，gs速度对A和内在水分利用效率（iWUE）的影响取决于一天中的时间。下午动力学出现挫折：绝对gs和gs对光的反应受到抑制，强烈限制A并影响昼夜iWUE。我们得出结论，不同的gs动力学的影响取决于目标光强、变化幅度、光强变化前的gs，尤其是一天中的时间。
