Abstract To understand the genetic and evolutionary basis of the responses to water deficit in plants, we turned to the basal liverwort Marchantia polymorpha, representing one of the most ancient plant lineages that first colonized land. Thalli exposed to water deficit showed a decreased growth rate and morphological modifications. In addition, water deficit led to relocation of cell organelles, mostly due to changes in volume of the central vacuole, which correlated with adjustments of osmotic potential. Abscisic acid (ABA) is a phytohormone that mediate responses to environmental stress in vascular plants. Consistently, we observed an increase in endogenous ABA levels upon water deficit in Marchantia, which correlated with the increased expression of genes encoding for LATE-EMBRYOGENESIS-ABUNDANT proteins, which are thought to protect cells from damage caused by water deficit. Transcriptome-level changes upon ABA and water deficit treatments revealed that several genes modify their expression under these conditions. Consistent with our cellular level observations, differentially expressed GO categories related to ion binding and transport may explain the changes in vacuole volume. Induction of stress-related genes, including several LEA genes, also points towards a possible conservation of ABA-dependent signaling pathways in M. polymorpha and defines a framework to understand the underlying molecular events.

中文翻译：

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导致地紫草中水分亏缺反应的早期事件

摘要 为了了解植物对水分亏缺反应的遗传和进化基础，我们转向了基础地草（Marchantia polymorpha），它代表了最古老的植物谱系之一，最早殖民土地。暴露于缺水的菌体显示出生长速度下降和形态改变。此外，水分不足导致细胞器的重新定位，主要是由于中央液泡体积的变化，这与渗透势的调整相关。脱落酸 (ABA) 是一种植物激素，可介导维管植物对环境胁迫的反应。一致地，我们观察到 Marchania 缺水时内源性 ABA 水平增加，这与编码 LATE-EMBRYOGENESIS-ABUNDANT 蛋白的基因表达增加有关，这被认为可以保护细胞免受水分不足造成的损害。ABA 和缺水处理后转录组水平的变化表明，在这些条件下，几个基因会改变它们的表达。与我们的细胞水平观察一致，与离子结合和运输相关的差异表达 GO 类别可以解释液泡体积的变化。胁迫相关基因（包括几个 LEA 基因）的诱导也表明了 M.polymorpha 中 ABA 依赖性信号通路的可能保守性，并定义了一个框架来了解潜在的分子事件。与离子结合和转运相关的差异表达 GO 类别可以解释液泡体积的变化。胁迫相关基因（包括几个 LEA 基因）的诱导也表明了 M.polymorpha 中 ABA 依赖性信号通路的可能保守性，并定义了一个框架来了解潜在的分子事件。与离子结合和转运相关的差异表达 GO 类别可以解释液泡体积的变化。胁迫相关基因（包括几个 LEA 基因）的诱导也表明了 M.polymorpha 中 ABA 依赖性信号通路的可能保守性，并定义了一个框架来了解潜在的分子事件。