A new study has been published recently in the academic journal “Plant Cell” on leaf senescence. SUSTech’s Department of Biology chair professor Guo Hongwei was part of the research group that led the study.
Leaf senescence is a highly coordinated, complicated process involving the integration of numerous internal and environmental signals. Salicylic acid (SA) and reactive oxygen species (ROS) are two well-defined inducers of leaf senescence whose contents progressively and inter-dependently increase during leaf senescence via an unknown mechanism. Here, we characterized the transcription factor WRKY75 as a positive regulator of leaf senescence in Arabidopsis thaliana. Knock-down or knock-out of WRKY75 delayed age-dependent leaf senescence, while over-expression of WRKY75 accelerated this process. WRKY75 transcription is induced by age, SA, H2O2, and multiple plant hormones. Meanwhile, WRKY75 promotes SA production by inducing the transcription of SA INDUCTION-DEFICIENT2 (SID2) and suppresses H2O2 scavenging, partly by repressing the transcription of CATALASE2 (CAT2).
Genetic analysis revealed that the mutation of SID2 or an increase in catalase activity rescued the precocious leaf senescence phenotype evoked by WRKY75 over-expression. Based on these results, we propose a tripartite amplification loop model in which WRKY75, SA, and ROS undergo a gradual but self-sustained rise driven by three interlinking positive feedback loops. This tripartite amplification loop provides a molecular framework connecting upstream signals, such as age and plant hormones, to the downstream regulatory network executed by SA- and H2O2-responsive transcription factors during leaf senescence.
Peking University & Tsinghua Life Science Joint Center (CLS) doctoral student Guo Pengru and postdoctoral researcher Dr. Li Zhonghai are the first authors for this article, and SUSTech’s Department of Biology Professor Guo Hongwei is the author of the communication. The study was supported by the National Natural Science Foundation of China, Peking University – Tsinghua Life Science Joint Center and the China Postdoctoral Fund.
Professor Guo Hongwei has been working on plant senescence for many years already and has published several research papers in the journal Plant Cell, Nucleic Acid Research and other magazines.
