Chen Wei, Zheng Yuchen, Wang Jingyi, Wang Zijing, Yang Zhen, Chi Xiaoyu, Dai Lingyan, Lu Guihua, Yang Yonghua, Sun Bo
State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210023, China.
College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang, 163319, China.
New Phytol. 2023 May;238(3):1129-1145. doi: 10.1111/nph.18757. Epub 2023 Feb 11.
The onset of leaf de-greening and senescence is governed by a complex regulatory network including environmental cues and internal factors such as transcription factors (TFs) and phytohormones, in which ethylene (ET) is one key inducer. However, the detailed mechanism of ET signalling for senescence regulation is still largely unknown. Here, we found that the WRKY TF SbWRKY50 from Sorghum bicolor L., a direct target of the key component ETHYLENE INSENSITIVE 3 in ET signalling, functioned for leaf senescence repression. The clustered regularly interspaced short palindromic repeats/CRISPR-associated protein9-edited SbWRKY50 mutant (SbWRKY5O-KO) of sorghum displayed precocious senescent phenotypes, while SbWRKY50 overexpression delayed age-dependent and dark-induced senescence in sorghum. SbWRKY50 negatively regulated chlorophyll degradation through direct binding to the promoters of several chlorophyll catabolic genes. In addition, SbWRKY50 recruited the Polycomb repressive complex 1 through direct interaction with SbBMI1A, to induce histone 2A mono-ubiquitination accumulation on the chlorophyll catabolic genes for epigenetic silencing and thus delayed leaf senescence. Especially, SbWRKY50 can suppress early steps of chlorophyll catabolic pathway via directly repressing SbNYC1 (NON-YELLOW COLORING 1). Other senescence-related hormones could also influence leaf senescence through repression of SbWRKY50. Hence, our work shows that SbWRKY50 is an essential regulator downstream of ET and SbWRKY50 also responds to other phytohormones for senescence regulation in sorghum.
叶片失绿和衰老的起始受一个复杂的调控网络控制，该网络包括环境信号和内部因素，如转录因子（TFs）和植物激素，其中乙烯（ET）是一个关键诱导因子。然而，ET信号传导调控衰老的详细机制仍 largely未知。在这里，我们发现来自双色高粱的WRKY TF SbWRKY50，是ET信号传导中关键组分乙烯不敏感3的直接靶标，其功能是抑制叶片衰老。高粱的成簇规律间隔短回文重复序列/CRISPR相关蛋白9编辑的SbWRKY50突变体（SbWRKY5O-KO）表现出早衰表型，而SbWRKY50过表达延迟了高粱中依赖年龄和黑暗诱导的衰老。SbWRKY50通过直接结合几个叶绿素分解代谢基因的启动子来负调控叶绿素降解。此外，SbWRKY50通过与SbBMI1A直接相互作用招募多梳抑制复合物1，以诱导叶绿素分解代谢基因上组蛋白2A单泛素化积累，从而进行表观遗传沉默，进而延迟叶片衰老。特别地，SbWRKY50可以通过直接抑制SbNYC1（非黄色着色1）来抑制叶绿素分解代谢途径的早期步骤。其他与衰老相关的激素也可以通过抑制SbWRKY50来影响叶片衰老。因此，我们的工作表明SbWRKY50是ET下游的一个重要调节因子，并且SbWRKY50也响应其他植物激素来调控高粱的衰老。
