Pereira Talitha S, Manandhar Anju, Cardoso Amanda A, Martins Samuel C V, McAdam Scott A M
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil.
Plant Physiol. 2025 Jun 25. doi: 10.1093/plphys/kiaf274.
Stomatal closure in response to water deficit is crucial for maintaining plant water balance. While the mechanisms driving daytime stomatal closure under drought are well studied, the mechanism driving progressive declines in nighttime transpiration (Enight) during drought remains less understood. To investigate whether either abscisic acid (ABA) or declining leaf water status drives progressive declines in nighttime transpiration during drought in vascular plants, we conducted experiments using representative fern, gymnosperm, and angiosperm species, including a severe ABA-deficient mutant and tree species. These species span a spectrum of stomatal control by ABA, ranging from insensitive to endogenous ABA in the fern to reliance on ABA for stomatal closure in the herbaceous angiosperm. We found that reductions in Enight during drought are driven by hydropassive stomatal closure in ferns and gymnosperms, transitioning to ABA regulation in gymnosperms under severe stress, and are triggered by ABA in herbaceous angiosperms. In all species, the proportion of total transpiration occurring at night increased as stomata closed during the drought. The reduction of nighttime transpiration during drought appears to be a convergent stomatal response across vascular land plants but is driven by diverse regulatory mechanisms linked to evolutionary history and ecological strategy.
气孔对水分亏缺做出响应而关闭，这对于维持植物水分平衡至关重要。虽然干旱期间驱动白天气孔关闭的机制已得到充分研究，但干旱期间驱动夜间蒸腾作用（夜间蒸腾速率）逐渐下降的机制仍不太清楚。为了研究脱落酸（ABA）或叶片水势下降是否驱动维管植物干旱期间夜间蒸腾作用的逐渐下降，我们使用了代表性的蕨类植物、裸子植物和被子植物物种进行实验，包括一个严重缺乏ABA的突变体和一些树种。这些物种涵盖了一系列由ABA控制气孔的类型，从蕨类植物对内源ABA不敏感，到草本被子植物依赖ABA进行气孔关闭。我们发现，干旱期间夜间蒸腾速率的降低在蕨类植物和裸子植物中是由水力被动气孔关闭驱动的，在严重胁迫下裸子植物转变为ABA调节，而在草本被子植物中是由ABA触发的。在所有物种中，随着干旱期间气孔关闭，夜间蒸腾占总蒸腾的比例增加。干旱期间夜间蒸腾作用的降低似乎是维管陆地植物中一种趋同的气孔响应，但由与进化历史和生态策略相关的多种调节机制驱动。
