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Ubiquitin‐conjugating enzyme (UBC) is a crucial component of the ubiquitin‐proteasome system, which contributes to plant growth and development. While some UBCs have been identified as potential regulators of abiotic stress responses, the underlying mechanisms of this regulation remain poorly understood. Here, we report a cotton (Gossypium hirsutum) UBC gene, GhUBC10‐2, which negatively regulates the salt stress response. We found that the gain of function of GhUBC10‐2 in both Arabidopsis (Arabidopsis thaliana) and cotton leads to reduced salinity tolerance. Additionally, GhUBC10‐2 interacts with glutathione S‐transferase (GST) U17 (GhGSTU17), forming a heterodimeric complex that promotes GhGSTU17 degradation. Intriguingly, GhUBC10‐2 can be self‐polyubiquitinated, suggesting that it possesses E3‐independent activity. Our findings provide new insights into the PTM of plant GST‐mediated salt response pathways. Furthermore, we found that the WRKY transcription factor GhWRKY13 binds to the GhUBC10‐2 promoter and suppresses its expression under salt conditions. Collectively, our study unveils a regulatory module encompassing GhWRKY13–GhUBC10‐2–GhGSTU17, which orchestrates the modulation of reactive oxygen species homeostasis to enhance salt tolerance. Summary statement: GhUBC10‐2 negatively regulates salt tolerance by targeting glutathione S‐transferase U17 (GhGSTU17) for its degradation. GhWRKY13 binds the W‐box of the GhUBC10‐2 promoter to repress GhUBC10‐2 transcription. The GhWRKY13–GhUBC10‐2–GhGSTU17 module offers a guidance for cotton breeding. [ABSTRACT FROM AUTHOR]

Phosphatases are important regulators of protein phosphorylation and various cellular processes, and they serve as counterparts to kinases. In this study, our comprehensive analysis of oomycete complete proteomes unveiled the presence of approximately 3833 phosphatases, with most species estimated to have between 100 and 300 putative phosphatases. Further investigation of these phosphatases revealed a significant increase in protein serine/threonine phosphatases (PSP) within oomycetes. In particular, we extensively studied the metallo‐dependent protein phosphatase (PPM) within the PSP family in the model oomycete Phytophthora sojae. Our results showed notable differences in the expression patterns of PPMs throughout 10 life stages of P. sojae, indicating their vital roles in various stages of oomycete pathogens. Moreover, we identified 29 PPMs in P. sojae, and eight of them possessed accessory domains in addition to phosphate domains. We investigated the biological function of one PPM protein with an extra PH domain (PPM1); this protein exhibited high expression levels in both asexual developmental and infectious stages. Our analysis confirmed that PPM1 is indeed an active protein phosphatase, and its accessory domain does not affect its phosphatase activity. To delve further into its function, we generated knockout mutants of PPM1 and validated its essential roles in mycelial growth, sporangia and oospore production, as well as infectious stages. To the best of our knowledge, this study provides the first comprehensive inventory of phosphatases in oomycetes and identifies an important phosphatase within the expanded serine/threonine phosphatase group in oomycetes. [ABSTRACT FROM AUTHOR]