Summary Abscisic acid (ABA) and jasmonic acid (JA) are important plant hormones in response to drought stress. We have identified that ZmHsf28 elevated ABA and JA accumulation to confer drought tolerance in maize; however, the underlying mechanism still remains elusive. The knockout line zmhsf28 is generated to confirm the positive role of ZmHsf28 in drought response. Multiple approaches are combined to reveal protein interaction among ZmHsf28, ZmSnRK2.2 and ZmJAZ14/17, which form a regulatory module to mediate maize drought tolerance through regulating ABA and JA key biosynthetic genes ZmNCED3 and ZmLOX8. Upon drought stress, zmhsf28 plants exhibit weaker tolerance than the WT plants with slower stomatal closure and more reactive oxygen species accumulation. ZmHsf28 interacted with ZmSnRK2.2 physically, resulting in phosphorylation at Ser220, which enhances binding to the heat shock elements of ZmNECD3 and ZmLOX8 promoters and subsequent gene expression. Meanwhile, ZmMYC2 upregulates ZmHsf28 gene expression through acting on the G‐box of its promoter. Besides, ZmJAZ14/17 competitively interact with ZmHsf28 to interfere with protein interaction between ZmHsf28 and ZmSnRK2.2, blocking ZmHsf28 phosphorylation and impairing downstream gene regulation. The ZmSnRK2.2‐ZmHsf28‐ZmJAZ14/17 module is identified to regulate drought tolerance through coordinating ABA and JA signaling, providing the insights for breeding to improve drought resistance in maize.

中文翻译：

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SnRK2.2‐ZmHsf28‐JAZ14/17 模块调节玉米的耐旱性


摘要： 脱落酸 （ABA） 和茉莉酸 （JA） 是响应干旱胁迫的重要植物激素。我们已经确定 ZmHsf28 提高了 ABA 和 JA 积累，从而赋予玉米耐旱性;然而，其潜在机制仍然难以捉摸。产生敲除系 zmhsf28 是为了证实 ZmHsf28 在干旱响应中的积极作用。结合多种方法揭示了 ZmHsf28、ZmSnRK2.2 和 ZmJAZ14/17 之间的蛋白质相互作用，它们形成一个调控模块，通过调控 ABA 和 JA 关键生物合成基因 ZmNCED3 和 ZmLOX8 介导玉米耐旱性。在干旱胁迫下，zmhsf28 植株表现出比 WT 植株更弱的耐受性，气孔关闭较慢，活性氧积累更多。ZmHsf28 与 ZmSnRK2.2 发生物理相互作用，导致 Ser220 磷酸化，从而增强与 ZmNECD3 和 ZmLOX8 启动子的热休克元件的结合以及随后的基因表达。同时，ZmMYC2 通过作用于其启动子的 G-box 上调 ZmHsf28 基因表达。此外，ZmJAZ14/17 与 ZmHsf28 竞争性相互作用，干扰 ZmHsf28 和 ZmSnRK2.2 之间的蛋白质相互作用，阻断 ZmHsf28 磷酸化并损害下游基因调控。ZmSnRK2.2‐ZmHsf28-ZmJAZ14/17 模块被确定通过协调 ABA 和 JA 信号传导来调节耐旱性，为育种提高玉米抗旱性提供见解。