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Article|02 Mar 2024|OPEN
CaSTH2 disables CaWRKY40 from activating pepper thermotolerance and immunity against Ralstonia solanacearum via physical interaction
Xingge Cheng1,2,3 ,† , Meiyun Wan1,2,3 ,† , Yuqiu Song1,2,3 , Qian Liu1,2,4 , Xiaohui Hu1,2,3 and Xiufang Chen1,2,3 , Xujing Zhang1,2,4 , Yapeng Zhang1,2,3 , Ruijie Wu1,2,3 , Qiaoling Lu1,2,3 , Yu Huang1,2,3 , Jingang Lv1,2,3 , WeiWei Cai5 , Deyi Guan1,2,3 , Sheng Yang1,6 , , Shuilin He,1,2,3 ,
1National Education Ministry Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
2Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
3College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
4College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
5College of of Horticultural Sciences, Zhejiang Agriculture and Forestry University, Hangzhou, Zhejiang, 350002, China
6Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, 100193, China
*Corresponding author. E-mail: 2022019@cau.edu.cn,shlhe@fafu.edu.cn
†Both authors contributed equally to the study.

Horticulture Research 11,
Article number: uhae066 (2024)
doi: https://doi.org/10.1093/hr/uhae066
Views: 1329

Received: 24 Oct 2023
Accepted: 21 Feb 2024
Published online: 02 Mar 2024

Abstract

CaWRKY40 coordinately activates pepper immunity against Ralstonia solanacearum infection (RSI) and high temperature stress (HTS), forms positive feedback loops with other positive regulators and is promoted by CaWRKY27b/CaWRKY28 through physical interactions; however, whether and how it is regulated by negative regulators to function appropriately remain unclear. Herein, we provide evidence that CaWRKY40 is repressed by a SALT TOLERANCE HOMOLOG2 in pepper (CaSTH2). Our data from gene silencing and transient overexpression in pepper and epoptic overexpression in Nicotiana benthamiana plants showed that CaSTH2 acted as negative regulator in immunity against RSI and thermotolerance. Our data from BiFC, CoIP, pull down, and MST indicate that CaSTH2 interacted with CaWRKY40, by which CaWRKY40 was prevented from activating immunity or thermotolerance-related genes. It was also found that CaSTH2 repressed CaWRKY40 at least partially through blocking interaction of CaWRKY40 with CaWRKY27b/CaWRKY28, but not through directly repressing binding of CaWRKY40 to its target genes. The results of study provide new insight into the mechanisms underlying the coordination of pepper immunity and thermotolerance.