CsBZIP40 confers resistance against citrus bacterial canker by repressing CsWRKY43-CsPrx53/CsSOD13 cascade mediated ROS scavenging

Abstract

As the bacterial etiologic agent causing citrus bacterial canker (CBC), Xanthomonas citri subsp. citri (Xcc) 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 (Citrus sinensis). 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.

Acknowledgements

The authors would like to thank all the reviewers who participated in the review and MJEditor (www.mjeditor.com) for its linguistic assistance during the preparation of this manuscript. This study was funded by the National Key Research and Development Program of China (2022YFD1201600, 2021YFD1600800), National Natural Sciences Foundation of China (32 202 425), Earmarked Funds for the China Agriculture Research System (CARS-26).

Author contributions

Q.Li, Y.H. and S.C. conceived and designed the experiments; Q.Li., X.Q., Q.Y., R.J., Q.Long, A.P., L.Y., J.Fan, J.Fu, and C.Z. performed the experiments; Q.Li, J.Fu, M.Z., B.X., W.Y., and Y.H. analysed the data; Q.Li wrote this article; all authors read and approved the final manuscript.

Data availability

The raw RNA-Seq data are archived as Sequence Read Archive (SRA) in the National Center for Biotechnology Information (NCBI) with an accession number PRJNA909460. Other data supporting the findings of this study are available within the article and supplementary data.

Conflict of interest statement

The authors declare no conflict of interests.

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