Li Qiang, Qin Xiujuan, Zhang Miao, Yu Qiyuan, Jia Ruirui, Fan Jie, Huang Xin, Fu Jia, Zhang Chenxi, Xian Baohang, Yang Wen, Long Qin, Peng Aihong, Yao Lixiao, Chen Shanchun, He Yongrui
Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Beibei, Chongqing 400712, China.
National Citrus Engineering Research Center, Beibei, Chongqing 400712, China.
Hortic Res. 2023 Jul 11;10(8):uhad138. doi: 10.1093/hr/uhad138. eCollection 2023 Aug.
As the bacterial etiologic agent causing citrus bacterial canker (CBC), subsp. () seriously impacts citrus plantation and fruit production globally. In an earlier study, we demonstrated that CsBZIP40 can positively impact CBC resistance in the sweet orange (). However, the mechanistic basis for the protective benefits conferred by CsBZIP40 is yet to be delineated. Here, we show that CsBZIP40 positively regulates CBC resistance and reactive oxygen species (ROS) homeostasis in transgenic sweet orange overexpressing CsBZIP40. CsBZIP40 directly binds to the TGA-box of the CsWRKY43 promoter to repress its transcriptional activity. CsWRKY43 overexpression induces CBC susceptibility in transgenic sweet oranges. In contrast, its inhibition produces strong resistance to CBC. CsWRKY43 directly binds to the W-boxes of the CsPrx53 and CsSOD13 promoters to positively regulate the activities of these antioxidant enzymes, resulting in the negative regulation of ROS homeostasis and CBC resistance in sweet orange plants. CsPrx53/CsSOD13 knockdown enhances ROS accumulation and CBC resistance. Overall, our results outline a regulatory pathway through which CsBZIP40 transcriptionally represses CsWRKY43-CsPrx53/CsSOD13 cascade-mediated ROS scavenging in a manner conducive to CBC resistance. These mechanisms underscore the potential importance of CsBZIP40, CsWRKY43, CsPrx53, and CsSOD13, providing promising strategies for the prevention of CBC.
作为引起柑橘溃疡病（CBC）的细菌病原体，亚种（）严重影响全球柑橘种植园和水果生产。在早期研究中，我们证明CsBZIP40可对甜橙（）中的CBC抗性产生积极影响。然而，CsBZIP40赋予保护作用的机制基础尚待阐明。在此，我们表明CsBZIP40在过表达CsBZIP40的转基因甜橙中正向调节CBC抗性和活性氧（ROS）稳态。CsBZIP40直接与CsWRKY43启动子的TGA框结合以抑制其转录活性。CsWRKY43过表达会诱导转基因甜橙对CBC敏感。相反，对其抑制则会产生对CBC的强抗性。CsWRKY43直接与CsPrx53和CsSOD13启动子的W框结合以正向调节这些抗氧化酶的活性，从而导致甜橙植株中ROS稳态和CBC抗性的负调节。CsPrx53/CsSOD13基因敲低增强了ROS积累和CBC抗性。总体而言，我们的结果勾勒出一条调控途径，通过该途径CsBZIP40以有利于CBC抗性的方式转录抑制CsWRKY43-CsPrx53/CsSOD13级联介导的ROS清除。这些机制强调了CsBZIP40、CsWRKY43、CsPrx53和CsSOD13的潜在重要性，为预防CBC提供了有前景的策略。
