AtWRKY75 positively regulates age-triggered leaf senescence through gibberellin pathway

Haiyan Zhang; Liping Zhang; Songguo Wu; Yanli Chen; Diqiu Yu; Ligang Chen

doi:10.1016/j.pld.2020.10.002

AtWRKY75 positively regulates age-triggered leaf senescence through gibberellin pathway

Plant Divers. 2020 Nov 1;43(4):331-340. doi: 10.1016/j.pld.2020.10.002. eCollection 2021 Aug.

Authors

Haiyan Zhang^{1

2}, Liping Zhang³, Songguo Wu^{1

2}, Yanli Chen^{1

2}, Diqiu Yu^{1

4}, Ligang Chen^{1

5}

Affiliations

¹ CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
² University of Chinese Academy of Sciences, Beijing, 100049, China.
³ CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, No. 132, Lanhei Road, Kunming, Yunnan, 650201, China.
⁴ State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Yunnan, 650091, China.
⁵ Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China.

Abstract

WRKY transcription factors play essential roles during leaf senescence. However, the mechanisms by which they regulate this process remains largely unknown. Here, we identified the transcription factor WRKY75 as a positive regulator during leaf senescence. Mutations of WRKY75 caused a delay in age-triggered leaf senescence, whereas overexpression of WRKY75 markedly accelerated this process. Expression of senescence-associated genes (SAGs) was suppressed in WRKY75 mutants but increased in WRKY75-overexpressing plants. Further analysis demonstrated that WRKY75 directly associates with the promoters of SAG12 and SAG29, to activate their expression. Conversely, GAI and RGL1, two DELLA proteins, can suppress the WRKY75-mediated activation, thereby attenuating SAG expression during leaf senescence. Genetic analyses showed that GAI gain-of-function or RGL1 overexpression can partially rescue the accelerated senescence phenotype caused by WRKY75 overexpression. Furthermore, WRKY75 can positively regulate WRKY45 expression during leaf senescence. Our data thus imply that WRKY75 may positively modulate age-triggered leaf senescence through the gibberellin-mediated signaling pathway.

Keywords: DELLAs; GA; Leaf senescence; WRKY75.