SbMPK13-mediated SbWRKY10 phosphorylation positively regulates SbGST40 expression required for cadmium tolerance in sorghum.

Cadmium (Cd) stress significantly affects the growth, development, and utilization of sorghum. Although the molecular pathways responding to Cd stress in sorghum remain incompletely understood, glutathione transferase (GST) is recognized for its critical role in plant responses to heavy metals and detoxification processes. In this study, we examined the influence of SbGST40 on Cd accumulation in sorghum. Our results indicate that SbGST40 is responsive to Cd stress, with its overexpression markedly enhancing Cd tolerance in sorghum while inhibiting Cd accumulation. Furthermore, we discovered that SbWRKY10 directly interacts with the promoter region of SbGST40, thereby augmenting its transcriptional activity. Additionally, SbMPK13 directly interacts with and phosphorylates SbWRKY10. Notably, in sorghum lines that overexpress SbMPK13, the protein stability of SbWRKY10 is enhanced, further amplifying the regulatory influence of SbWRKY10 on SbGST40 expression. Collectively, our findings elucidate the role of the module comprising SbMPK13, SbWRKY10, and SbGST40, which is crucial for mediating Cd accumulation in sorghum.