Drought stress inhibits plant growth and agricultural production. Improving plant instantaneous water use efficiency (iWUE), which is strictly regulated by stomata, is an effective way to cope with drought stress. However, the mechanisms of iWUE regulation are poorly understood. Through genetic screening for suppressors of mpk12-4, an Arabidopsis (Arabidopsis thaliana) mutant with a major iWUE quantitative trait locus gene MITOGEN-ACTIVATED PROTEIN KINASE12 deleted, we identified HIGH LEAF TEMPERATURE1 (HT1). Genetic interaction and physiological analyses showed that MPK12 controls iWUE through multiple modules in a high CO2-induced stomatal closing pathway that regulate SLOW ANION CHANNEL-ASSOCIATED1 (SLAC1) activity. HT1 acts downstream of MPK12, whereas OPEN STOMATA1 (OST1) and GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1) function downstream of HT1 by activating SLAC1 in iWUE. Photosynthetic-CO2 response curves and biomass analyses under different water-supply conditions showed that HT1 dysfunction improved iWUE and also increased plant growth capacity, and products of HT1 putative orthologs from Brassica (Brassica napus) and rice (Oryza sativa) exhibited functions similar to that of Arabidopsis HT1 in iWUE and the CO2-signaling pathway. Our study revealed the mechanism of MPK12-mediated iWUE regulation in Arabidopsis and provided insight into the internal relationship between iWUE and CO2 signaling in guard cells and a potential target for improving crop iWUE and drought tolerance.

中文翻译：

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涉及 HIGH LEAF TEMPERATURE1 的模块控制瞬时水分利用效率


干旱胁迫抑制植物生长和农业生产。提高受气孔严格调控的植物瞬时水分利用效率（iWUE）是应对干旱胁迫的有效途径。然而，人们对 iWUE 调节机制知之甚少。通过对 mpk12-4（一种拟南芥（Arabidopsis thaliana）突变体，其主要 iWUE 数量性状基因座基因 MITOGEN-ACTIVATED PROTEIN KINASE12 缺失）的抑制子进行遗传筛选，我们鉴定了 HIGH LEAF TEMPERATURE1 (HT1)。遗传相互作用和生理分析表明，MPK12 通过高 CO2 诱导的气孔关闭途径中的多个模块控制 iWUE，该途径调节慢阴离子通道相关 1 (SLAC1) 活性。 HT1 作用于 MPK12 下游，而 OPEN STOMATA1 (OST1) 和保护细胞过氧化氢抵抗 1 (GHR1) 通过激活 iWUE 中的 SLAC1 在 HT1 下游发挥作用。不同供水条件下的光合-CO2响应曲线和生物量分析表明，HT1功能障碍改善了iWUE并提高了植物生长能力，并且来自甘蓝型油菜（Brassica napus）和水稻（Oryza sativa）的HT1推定直系同源物的产物表现出与HT1相似的功能拟南芥 HT1 在 iWUE 和 CO2 信号通路中的作用。我们的研究揭示了拟南芥中 MPK12 介导的 iWUE 调节机制，并深入了解保卫细胞中 iWUE 和 CO2 信号传导之间的内部关系，以及改善作物 iWUE 和耐旱性的潜在目标。