Leaf senescence is an integral part of plant development, during which, nutrients are remobilized from senescent leaves to fast‐growing organs. The initiation and progression dynamics of leaf senescence is therefore vital not only to the maximal accumulation of assimilates but also to the efficient remobilization of nutrients. Senescence is a finely tuned process that involves the action of a large number of transcription factors (TFs). The NAC TFs play critical roles in regulating leaf senescence in Arabidopsis, wheat, rice and tomato. Here, we identified a NAC TF, ZmNAC126 that is responsive to leaf senescence in maize. Ectopic overexpression of ZmNAC126 in Arabidopsis and maize enhanced chlorophyll degradation and promoted leaf senescence. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that ZmNAC126 could directly bind to the promoters of major chlorophyll catabolic genes in maize. Dual‐luciferase assay in maize protoplasts indicated that ZmNAC126 positively regulates these chlorophyll catabolic genes in maize. Moreover, ZmNAC126 could be induced by ethylene, and ZmEIN3, a major TF of ethylene signalling, could bind to its promoter to transactivate its expression. Taken together, ZmNAC126 may play a pivotal role in regulating natural and ethylene‐triggered leaf senescence in maize.

中文翻译：

---

转录因子ZmNAC126促进玉米中乙烯信号途径下游的叶片衰老。

叶片衰老是植物发育不可或缺的一部分，在此过程中，养分从衰老的叶片中转移到了快速生长的器官中。因此，叶片衰老的起始和进展动力学不仅对同化物的最大积累至关重要，而且对养分的有效转运也至关重要。衰老是一个微调的过程，涉及大量转录因子（TF）的作用。NAC TF在调节拟南芥，小麦，水稻和番茄的叶片衰老中起关键作用。在这里，我们确定了一个NAC TF ZmNAC126，它对玉米叶片的衰老有反应。ZmNAC126在拟南芥中的异位过表达玉米促进叶绿素降解并促进叶片衰老。电泳迁移率变化和染色质免疫沉淀分析表明，ZmNAC126可以直接结合玉米中主要叶绿素分解代谢基因的启动子。玉米原生质体中的双荧光素酶测定表明ZmNAC126积极调节玉米中的这些叶绿素分解代谢基因。此外，ZmNAC126可以被乙烯诱导，而ZmEIN3，乙烯信号的主要TF，可以与其启动子结合，从而激活其表达。综上所述，ZmNAC126可能在调节玉米天然和乙烯触发的叶片衰老中起关键作用。