Salicylic acid reduces MdPUB24-mediated ubiquitination of MdWRKY40 to suppress ethylene biosynthesis in apple fruit

Abstract

The plant hormone salicylic acid (SA) effectively suppresses ethylene biosynthesis in apple (Malus domestica) fruit. However, the underlying molecular mechanism remains unclear. Here, we identified a WRKY transcription factor, MdWRKY40, which was upregulated in response to SA treatment. MdWRKY40 functioned as a transcriptional repressor of the ethylene biosynthesis gene MdACS1 (1-aminocyclopropane-1-carboxylic acid synthase 1). In addition, we found that the expression of U-box-type E3 ubiquitin ligase MdPUB24 was downregulated following SA treatment. MdPUB24 interacted with MdWRKY40 and mediated its ubiquitination, leading to the degradation of MdWRKY40 via the 26S proteasome pathway, which was suppressed by SA. Together, these results suggest that the MdPUB24-MdWRKY40-MdACS1 regulatory module mediates SA-induced suppression of ethylene biosynthesis by post-translational modification during apple fruit ripening. These findings offer new insights into the molecular basis of fruit ripening inhibition and shelf-life extension.

Acknowledgements

This work was supported by the Liaoning Provincial Major Special Project of Science and Technology (2025JH1/11700014) and the National Natural Science Foundation of China (32402532). We thank Editage (https://www.editage.cn/) for editing the manuscript.

Authors contributions

Y.J. and J.J. conceived and designed the study. J.J. performed most of the experiments. S.L. measured the content of SA. W.L. analyzed the data. Y.J. and J.J. wrote the article. Y.J. and A.W. revised the article. All authors analyzed the data and discussed the article.

Data availability

The sequence information discussed in this article is accessible through the Genome Database for Rosaceae (https://www.rosaceae.org) or in the Genbank/EMBL libraries, identified by their accession numbers MdWRKY40 (MD00G1143600), MdPUB24 (MD12G1040800), MdACS1 (U89156), MdACO1 (AF030859), and Actin (EB13 6338).

Conflicts of interest statement

The authors declare no conflict of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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