Rodriguez-Dominguez Celia M, Buckley Thomas N, Egea Gregorio, de Cires Alfonso, Hernandez-Santana Virginia, Martorell Sebastia, Diaz-Espejo Antonio
Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain.
Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain.
Plant Cell Environ. 2016 Sep;39(9):2014-26. doi: 10.1111/pce.12774. Epub 2016 Jul 15.
Reduced stomatal conductance (gs ) during soil drought in angiosperms may result from effects of leaf turgor on stomata and/or factors that do not directly depend on leaf turgor, including root-derived abscisic acid (ABA) signals. To quantify the roles of leaf turgor-mediated and leaf turgor-independent mechanisms in gs decline during drought, we measured drought responses of gs and water relations in three woody species (almond, grapevine and olive) under a range of conditions designed to generate independent variation in leaf and root turgor, including diurnal variation in evaporative demand and changes in plant hydraulic conductance and leaf osmotic pressure. We then applied these data to a process-based gs model and used a novel method to partition observed declines in gs during drought into contributions from each parameter in the model. Soil drought reduced gs by 63-84% across species, and the model reproduced these changes well (r(2) = 0.91, P < 0.0001, n = 44) despite having only a single fitted parameter. Our analysis concluded that responses mediated by leaf turgor could explain over 87% of the observed decline in gs across species, adding to a growing body of evidence that challenges the root ABA-centric model of stomatal responses to drought.
被子植物在土壤干旱期间气孔导度（gs）降低，可能是由于叶片膨压对气孔的影响和/或不直接依赖于叶片膨压的因素，包括根系产生的脱落酸（ABA）信号。为了量化叶片膨压介导和不依赖叶片膨压的机制在干旱期间气孔导度下降中的作用，我们在一系列旨在使叶片和根系膨压产生独立变化的条件下，测量了三种木本植物（杏仁、葡萄和橄榄）的气孔导度干旱响应和水分关系，包括蒸发需求的日变化以及植物水力导度和叶片渗透压的变化。然后，我们将这些数据应用于基于过程的气孔导度模型，并使用一种新方法将干旱期间观察到的气孔导度下降划分为模型中每个参数的贡献。土壤干旱使各物种的气孔导度降低了63 - 84%，尽管该模型只有一个拟合参数，但仍能很好地再现这些变化（r(2) = 0.91，P < 0.0001，n = 44）。我们的分析得出结论，叶片膨压介导的响应可以解释各物种中观察到的超过87%的气孔导度下降，这进一步证明了越来越多的证据对以根系ABA为中心的气孔对干旱响应模型提出了挑战。
