Unraveling the role of Cullin3 of E3 ubiquitin ligase in salt stress tolerance via proteomics.

backgroundAn association of OsCUL3c with salt tolerance has been found by a genome-wide association studies (GWAS) in rice. However, its functions and mechanisms remain unexplored. We aimed to examine the role of Cullin3 of E3 ubiquitin ligase in salt stress responses.

resultsProteomic analyses were performed to compare the Atcul3a mutant and wild type (WT) plants under salt stress. Our results demonstrated that an Arabidopsis mutant of Cullin3a (Atcul3a), an OsCUL3c homolog, exhibits a more sensitive phenotype under salt stress than the WT. Differentially expressed proteins (DEPs) that were non-salt-responsive demonstrated an overrepresentation of Gene Ontology (GO) terms associated with photosynthesis. Conversely, salt-responsive DEPs exhibited enriched GO terms linked to responses to toxic substances and involvement in glutathione metabolism. The role of OsCUL3c in salt tolerance was further supported by its heterologous expression in Arabidopsis. We cloned the rice OsCUL3c gene and expressed it in Arabidopsis, both in WT and Atcul3a mutant backgrounds. Complementation and over-expression lines featuring OsCUL3c expression displayed a higher germination rate, enhanced growth, and elevated photosynthetic pigment content under salt stress compared to the mutant line. Over-representation analysis on the combined proteomic datasets revealed major processes affected by the Cullin3 mutation and overexpression, which included glutathione metabolism, carbon metabolism, photosynthesis, and translation. Upregulation of several key genes in glutathione metabolism and carbon metabolism; and downregulation of specific photosynthetic and ribosomal proteins indicate a shift toward enhanced oxidative defense and metabolic reprogramming under salt stress conditions.

conclusionsThese findings highlight Cullin3 as a key salt tolerance regulator by coordinating multiple pathways.