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Article|17 Oct 2023|OPEN
Red light induces salicylic acid accumulation by activating CaHY5 to enhance pepper resistance against Phytophthora capsici 
Youxin Yang1 , Yu Li1 , Yelan Guang1 , Jinhui Lin4 , Yong Zhou1 , Ting Yu1 , Fei Ding5 , Yanfeng Wang2 , Jinyin Chen1 , Yanhong Zhou3 , and Fengfeng Dang,2 ,
1Jiangxi Key Laboratory for Postharvest Technology and Nondestructive Testing of Fruits & Vegetables, Collaborative Innovation Center of Post-Harvest Key Technology and Quality Safety of Fruits and Vegetables, College of Agronomy, Jiangxi Agricultural University, Nanchang, 330045, China
2Shaanxi Key Laboratory of Chinese Jujube, Yan’an University, Yan’an, Shaanxi 716000, China
3Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou, 310058, China
4Fruit Research Institute, Fujian Academy of Agricultural science, Fuzhou 350013, China
5School of Life Sciences, Liaocheng University, Liaocheng 252000, China
*Corresponding author. E-mail: yanhongzhou@zju.edu.cn,fdang@yau.edu.cn

Horticulture Research 10,
Article number: uhad213 (2023)
doi: https://doi.org/10.1093/hr/uhad213
Views: 170

Received: 31 Jul 2023
Accepted: 10 Oct 2023
Published online: 17 Oct 2023

Abstract

Pepper (Capsicum annuum L.) is frequently challenged by various pathogens, among which Phytophthora capsici is the most devastating to pepper production. Red light signal acts as a positive induction of plant resistance against multiple pathogens. However, little is known about how the red light signal affects pepper resistance to P. capsici infection (PCI). Here, we report that red light regulates salicylic acid (SA) accumulation by activating elongated hypocotyl5 (CaHY5), a basic leucine zipper (bZIP) transcription factor, thereby decreasing pepper susceptibility to PCI. Exogenous SA treatment reduced pepper susceptibility to PCI, while silencing of CaPHYB (a red light photoreceptor) increased its susceptibility. PCI significantly induced CaHY5 expression, and silencing of CaHY5 reduced SA accumulation, accompanied by decreases in the expression levels of phenylalanine ammonia-lyase 3 (CaPAL3)CaPAL7pathogenesis-related 1 (CaPR1), and CaPR1L, which finally resulted in higher susceptibility of pepper to PCI. Moreover, CaHY5 was found to activate the expression of CaPAL3 and CaPAL7, which are essential for SA biosynthesis, by directly binding to their promoters. Further analysis revealed that exogenous SA treatment could restore the resistance of CaHY5­silenced pepper plants to PCI. Collectively, this study reveals a critical mechanism through which red light induces SA accumulation by regulating CaHY5­mediated CaPAL3 and CaPAL7 expression, leading to enhanced resistance to PCI. Moreover, red light-induced CaHY5 regulates pepper resistance to PCI, which may have implications for PCI control in protected vegetable production.