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Article|04 May 2023|OPEN
ABI5 promotes heat stress-induced chlorophyll degradation by modulating the stability of MYB44 in cucumber 
Weikang Liu1 , Guangling Chen1 , Mingming He1 , Jianqiang Wu1 , Wenxu Wen1 , Qinsheng Gu2 , Shirong Guo1 , , Yu Wang1 and Jin Sun,1 ,
1College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
2Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou 450009, China
*Corresponding author. E-mail:,

Horticulture Research 10,
Article number: uhad089 (2023)
Views: 187

Received: 07 Sep 2022
Accepted: 27 Apr 2023
Published online: 04 May 2023


The yellowing of leaves caused by the decomposition of chlorophyll (Chl) is a characteristic event during senescence, which can be induced by various environmental stresses. However, the molecular mechanisms of high temperature-induced Chl degradation in horticultural plants remain poorly understood. Here, we found that heat stress induced Chl degradation and the expression of ABI5 and MYB44 in cucumber. Silencing of ABI5 compromised heat stress-induced Chl degradation, and the transcription of pheophytinase (PPH) and pheophorbide a oxygenase (PAO), two key genes in Chl catabolic pathway, but silencing of MYB44 exhibited the opposite results. Furthermore, ABI5 interacted with MYB44 in vitro and in vivo. ABI5 positively regulated heat stress-induced Chl degradation through two pathways. ABI5 directly bound to PPH and PAO promoters to promote their expression, leading to accelerating Chl degradation. On the other hand, the interaction between ABI5 and MYB44 reduced the binding of MYB44 to PPH and PAO promoters and led to the ubiquitination-depended protein degradation of MYB44, thereby alleviating the transcription inhibitory effect of MYB44 on PPH and PAO. Taken together, our findings propose a new regulatory network for ABI5 in regulating heat stress-induced Chl degradation.