Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.
Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
Plant Cell. 2023 Sep 27;35(10):3782-3808. doi: 10.1093/plcell/koad200.
Plant genomes encode many receptor-like kinases (RLKs) that localize to the cell surface and perceive a wide variety of environmental cues to initiate downstream signaling cascades. Whether these RLKs participate in dehydration stress signaling in plants is largely unknown. DROOPY LEAF1 (DPY1), a leucine-rich repeat (LRR)-RLK, was recently shown to regulate plant architecture by orchestrating early brassinosteroid signaling in foxtail millet (Setaria italica). Here, we show that DPY1 is essential for the acclimation of foxtail millet to drought stress. DPY1 can be phosphorylated and activated in response to osmotic stress and is required for more than half of osmotic stress-induced global phosphorylation events, including the phosphorylation of sucrose nonfermenting kinase 2s (SnRK2s), the central kinases involved in osmotic stress. DPY1 acts upstream of STRESS-ACTIVATED PROTEIN KINASE 6 (SAPK6, a subclass I SnRK2) and is required for full SAPK6 activation, thereby allowing regulation of downstream genes to mount a response against drought stress. These signaling events are largely independent of DPY1-mediated brassinosteroid signaling. The DPY1-SAPK6 module is specific to seed plants and is absent in ancestral nonseed plants. Our findings reveal a dehydration stress-activated RLK that plays an indispensable role in osmotic stress signaling and mediates SnRK2 activation at the cell surface.
植物基因组编码许多位于细胞表面的受体样激酶 (RLKs)，它们可以感知多种环境信号，从而启动下游信号级联反应。这些 RLKs 是否参与植物的脱水应激信号转导在很大程度上尚不清楚。DRY-LEAF1 (DPY1)，一种富含亮氨酸重复序列 (LRR)-RLK，最近被证明通过协调早期油菜素甾醇信号在谷子 (Setaria italica) 中调节植物结构。在这里，我们表明 DPY1 对于谷子适应干旱胁迫是必不可少的。DPY1 可以响应渗透胁迫而被磷酸化和激活，并且是超过一半的渗透胁迫诱导的全局磷酸化事件所必需的，包括蔗糖非发酵激酶 2s (SnRK2s) 的磷酸化，这是参与渗透胁迫的核心激酶。DPY1 在应激激活蛋白激酶 6 (SAPK6，一种 I 类 SnRK2) 的上游起作用，并且是 SAPK6 完全激活所必需的，从而允许调节下游基因以响应干旱胁迫。这些信号事件在很大程度上独立于 DPY1 介导的油菜素信号。DPY1-SAPK6 模块是种子植物特有的，在原始非种子植物中不存在。我们的发现揭示了一种脱水应激激活的 RLK，它在渗透胁迫信号转导中起着不可或缺的作用，并在细胞表面介导 SnRK2 的激活。
