Summary Leaf senescence is a complex process regulated by developmental and environmental factors, and plays a pivotal role in the development and life cycle of higher plants. Casein kinase 1 (CK1) is a highly conserved serine/threonine protein kinase in eukaryotes and functions in various cellular processes including cell proliferation, light signaling and hormone effects of plants. However, the biological function of CK1 in plant senescence remains unclear. Through systemic genetic and biochemical studies, we here characterized the function of Arabidopsis EL1‐like (AEL), a CK1, in promoting leaf senescence by stimulating ethylene biosynthesis through phosphorylating transcription factor WRKY22. Seedlings lacking or overexpressing AELs presented delayed or accelerated leaf senescence, respectively. AELs interact with and phosphorylate WRKY22 at Thr57, Thr60 and Ser69 residues to enhance whose transactivation activity. Being consistent, increased or suppressed phosphorylation of WRKY22 resulted in the promoted or delayed leaf senescence. WRKY22 directly binds to promoter region and stimulates the transcription of 1‐amino‐cyclopropane‐1‐carboxylate synthase 7 gene to promote ethylene level and hence leaf senescence. Our studies demonstrated the crucial role of AEL‐mediated phosphorylation in regulating ethylene biosynthesis and promoting leaf senescence by enhancing WRKY22 transactivation activity, which helps to elucidate the fine‐controlled ethylene biosynthesis and regulatory network of leaf senescence.

中文翻译：

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酪蛋白激酶 1 AEL 通过磷酸化 WRKY22 转录因子增强乙烯生物合成，从而促进衰老


摘要 叶片衰老是一个受发育和环境因素调控的复杂过程，在高等植物的发育和生命周期中发挥着关键作用。酪蛋白激酶 1 (CK1) 是真核生物中高度保守的丝氨酸/苏氨酸蛋白激酶，在多种细胞过程中发挥作用，包括细胞增殖、光信号传导和植物的激素效应。然而，CK1在植物衰老中的生物学功能仍不清楚。通过系统遗传和生化研究，我们表征了拟南芥 EL1 样 (AEL)（一种 CK1）通过磷酸化转录因子 WRKY22 刺激乙烯生物合成来促进叶片衰老的功能。缺乏或过度表达 AEL 的幼苗分别表现出叶片衰老延迟或加速。 AEL 与 WRKY22 的 Thr57、Thr60 和 Ser69 残基相互作用并使其磷酸化，以增强其反式激活活性。 WRKY22 磷酸化的一致、增加或抑制导致叶片衰老的促进或延迟。 WRKY22 直接结合启动子区域并刺激 1-氨基-环丙烷-1-羧酸合酶 7 基因的转录，以促进乙烯水平，从而促进叶片衰老。我们的研究证明了AEL介导的磷酸化通过增强WRKY22反式激活活性在调节乙烯生物合成和促进叶片衰老中的关键作用，这有助于阐明精细控制的乙烯生物合成和叶片衰老的调控网络。