The transcription factor MdWRKY9 is involved in jasmonic acid-mediated salt stress tolerance in apple

Abstract

Salt stress is an important abiotic stress affecting the growth and fruit quality of apple fruits. Although jasmonic acid (JA) hormones and WRKY transcription factors (TFs) have both been reported to be involved in plant salt stress responses, the molecular mechanisms by which JA-mediated WRKY TFs regulate salt stress in apples remain unclear. Here, we report the identification of a WRKY family TF from apple, MdWRKY9, and its involvement in apple salt tolerance by regulating the expression of Na⁺/H⁺ antiporters, MdNHX1, and MdSOS2. Furthermore, we show that the protein repressors MdJAZ5 and MdJAZ10 in the JA signaling pathway can both interact with MdWRKY9 to form a complex and inhibit its DNA-binding and transcriptional activation activity. The JA signal triggers the degradation of MdJAZ5 and MdJAZ10 proteins by the 26S proteasome, disrupting the JAZ-WRKY protein complex and thereby releasing MdWRKY9 to activate downstream gene expression, promoting salt tolerance in apples. These findings provide important insights into the molecular mechanism of the WRKY TFs in JA-mediated salt tolerance in plants.

Acknowledgements

We thank Dr Yicheng Wang from Nanjing Forestry University and Dr Shuhui Zhang from Northwest A&F University for constructive comments on the manuscript and Dr Chen Wang from Shandong Agricultural University for providing the vectors. This work was supported by the Key Research and development Programs of Shandong Provence (2023CXPT013, 2022CXPT021), the National Key R&D Program of China (No.2023YFD1200100), and the Youth Innovation Team Program of Shandong Province (2022KJ236).

Author contributions

J.H.Z. and W.J.L. designed the experiments. N.W. and J.H.Z. wrote the paper. Z.J.C., Z.Y.Z., and X.S.C. edited and improved the manuscript. J.H.Z., S.H.Z., Z.C.Y., T.T.G., and J.Z. performed the experiments and analyzed the data. L.Y.M. made contributions in growing plant materials. All authors read and approved the manuscript.

Data availability

We confirm that data supporting the results are available in the present article and its Supplementary Information. RNA-seq data that support the findings of this study have been deposited in the NCBI Bioproject database under accession number PRJNA1047940.

Conflict of interest statement

The authors declare that there is no conflict of interest.

Supplementary Data

Supplementary data is available at Horticulture Research online.

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