Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA.
Department of Integrative Biology, University of Texas at Austin, 2415 Speedway, Austin, TX, 78712, USA.
Nat Commun. 2019 Jul 30;10(1):3398. doi: 10.1038/s41467-019-11006-1.
Stomata, the microvalves on leaf surfaces, exert major influences across scales, from plant growth and productivity to global carbon and water cycling. Stomatal opening enables leaf photosynthesis, and plant growth and water use, whereas plant survival of drought depends on stomatal closure. Here we report that stomatal function is constrained by a safety-efficiency trade-off, such that species with greater stomatal conductance under high water availability (g) show greater sensitivity to closure during leaf dehydration, i.e., a higher leaf water potential at which stomatal conductance is reduced by 50% (Ψ). The g - Ψ trade-off and its mechanistic basis is supported by experiments on leaves of California woody species, and in analyses of previous studies of the responses of diverse flowering plant species around the world. Linking the two fundamental key roles of stomata-the enabling of gas exchange, and the first defense against drought-this trade-off constrains the rates of water use and the drought sensitivity of leaves, with potential impacts on ecosystems.
气孔是叶片表面的微型阀门，在多个尺度上对植物的生长和生产力、全球碳和水循环都有着重要的影响。气孔的开启使叶片能够进行光合作用和植物生长以及水分利用，而植物对干旱的适应则取决于气孔的关闭。在这里，我们报告说，气孔功能受到安全-效率权衡的限制，例如，在高水分可用性下具有更大气孔导度（g）的物种，在叶片脱水时对关闭更为敏感，即气孔导度降低 50%时的叶片水势（Ψ）更高。该 g-Ψ 权衡及其机械基础得到了加利福尼亚木本物种叶片实验和对全球不同开花植物物种响应的先前研究分析的支持。将气孔的两个基本关键作用联系起来——促进气体交换和抵御干旱的第一道防线——这种权衡限制了叶片的水分利用速率和对干旱的敏感性，这可能会对生态系统产生影响。
