Scoffoni Christine, Kunkle Justin, Pasquet-Kok Jessica, Vuong Christine, Patel Amish J, Montgomery Rebecca A, Givnish Thomas J, Sack Lawren
Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA.
Office of Research, Western Kentucky University, 1906 College Heights Blvd #11026, Bowling Green, KY, 42101, USA.
New Phytol. 2015 Jul;207(1):43-58. doi: 10.1111/nph.13346. Epub 2015 Apr 8.
Leaf hydraulic conductance (Kleaf ) quantifies the capacity of a leaf to transport liquid water and is a major constraint on light-saturated stomatal conductance (gs ) and photosynthetic rate (Amax ). Few studies have tested the plasticity of Kleaf and anatomy across growth light environments. These provided conflicting results. The Hawaiian lobeliads are an excellent system to examine plasticity, given the striking diversity in the light regimes they occupy, and their correspondingly wide range of Amax , allowing maximal carbon gain for success in given environments. We measured Kleaf , Amax , gs and leaf anatomical and structural traits, focusing on six species of lobeliads grown in a common garden under two irradiances (300/800 μmol photons m(-2) s(-1) ). We tested hypotheses for light-induced plasticity in each trait based on expectations from optimality. Kleaf , Amax , and gs differed strongly among species. Sun/shade plasticity was observed in Kleaf , Amax, and numerous traits relating to lamina and xylem anatomy, venation, and composition, but gs was not plastic with growth irradiance. Species native to higher irradiance showed greater hydraulic plasticity. Our results demonstrate that a wide set of leaf hydraulic, stomatal, photosynthetic, anatomical, and structural traits tend to shift together during plasticity and adaptation to diverse light regimes, optimizing performance from low to high irradiance.
叶片水力导度（Kleaf）量化了叶片运输液态水的能力，是对光饱和气孔导度（gs）和光合速率（Amax）的主要限制因素。很少有研究测试过Kleaf和解剖结构在不同生长光照环境下的可塑性。这些研究给出了相互矛盾的结果。鉴于夏威夷半边莲属植物所占据的光照条件具有显著多样性，以及它们相应广泛的Amax范围，使其能在特定环境中实现最大的碳获取量，因此该属植物是研究可塑性的绝佳系统。我们测量了Kleaf、Amax、gs以及叶片的解剖和结构特征，重点关注了在两种辐照度（300/800 μmol光子·m⁻²·s⁻¹）下于共同园圃中生长的六种半边莲属植物。我们基于最优性预期对每个性状的光诱导可塑性进行了假设检验。Kleaf、Amax和gs在不同物种间差异很大。在Kleaf、Amax以及许多与叶片和木质部解剖结构、叶脉和组成相关的性状中观察到了阳生/阴生可塑性，但gs并未随生长辐照度发生可塑性变化。原产于较高辐照度环境的物种表现出更大的水力可塑性。我们的结果表明，在可塑性和适应不同光照条件的过程中，一系列广泛的叶片水力、气孔、光合、解剖和结构性状往往会共同发生变化，从而优化从低到高辐照度下的性能表现。
