Leaf senescence is a highly complex developmental process that is tightly controlled by multiple layers of regulation. Abscisic acid (ABA) and reactive oxygen species (ROS) are two well‐known factors that promote leaf senescence. We show here that the transcription factor CDF4 positively regulates leaf senescence. Constitutive and inducible overexpression of CDF4 accelerates leaf senescence, while knockdown of CDF4 delays it. CDF4 increases endogenous ABA levels by upregulating the transcription of the ABA biosynthesis genes 9‐cis‐epoxycarotenoid dioxygenase 2, 3 (NCED2, 3 ) and suppresses H₂O₂ scavenging by repressing expression of the catalase2 (CAT2 ) gene. NCED2, 3 knockout and CAT2 overexpression partially rescue premature leaf senescence caused by CDF4 overexpression. We also show that CDF4 promotes floral organ abscission by activating the polygalacturonase PGAZAT gene. Based on these results, we propose that the levels of CDF4, ABA, and ROS undergo a gradual increase driven by their interlinking positive feedback loops during the leaf senescence and floral organ abscission processes.

中文翻译：

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转录因子 CDF4 通过调节拟南芥中的脱落酸和活性氧途径促进叶片衰老和花器官脱落。

叶片衰老是一个高度复杂的发育过程，受到多层调控的严格控制。脱落酸 (ABA) 和活性氧 (ROS) 是两个众所周知的促进叶片衰老的因素。我们在这里显示转录因子CDF4正调节叶片衰老。CDF4的组成型和诱导型过表达加速了叶片衰老，而CDF4的敲低则延迟了它。CDF4通过上调 ABA 生物合成基因 9-顺-环氧类胡萝卜素双加氧酶 2, 3 ( NCED2, 3 ) 的转录来增加内源性 ABA 水平，并通过抑制过氧化氢酶 2 的表达来抑制 H ₂ O ₂的清除 (CAT2 ) 基因。NCED2、3敲除和CAT2过表达部分挽救了由CDF4过表达引起的叶片过早衰老。我们还表明，CDF4通过激活多聚半乳糖醛酸酶PGAZAT基因促进花器官脱落。基于这些结果，我们提出在叶片衰老和花器官脱落过程中，CDF4、ABA 和 ROS 的水平在它们相互关联的正反馈回路的驱动下逐渐增加。