CvbZIP81 contributes to selenium accumulation by regulating sulfate transports in Cardamine violifolia

Selenium is an essential micronutrient for humans and animals, known for its antioxidant characteristics, regulation of thyroid hormone metabolism, enhancement of immune function, and elevated antiviral and anticancer activities. Cardamine violifolia is a recognized selenium hyperaccumulator; however, the mechanistic basis of selenium uptake and accumulation in this species remains unexplored. In this study, we combined molecular biology, physiology, and bioinformatics approaches to elucidate the role of bZIP transcription factor family in these processes. A total of 94 members of the bZIP family were identified in C. violifolia. Phylogenetic analysis classified these 94 members into 11 distinct subfamilies. Promoter analysis revealed that the promoter regions of these CvbZIP genes are enriched in cis-acting elements associated with stress responses, growth, and development. Through gene expression and correlation analyses, we identified CvbZIP81 as a nuclear-localized transcription factor that promotes selenium accumulation in C. violifolia by transcriptionally activating SULTR1;2.1, thereby facilitating selenium uptake. This study expands the functional network of bZIP transcription factors and reveals their regulatory role in selenium accumulation in C. violifolia, providing foundational insights and candidate targets for the functional validation of CvbZIP genes and the development of high-selenium cultivars.