Uncovering the transcriptional regulatory network underlying selenium tolerance in maize seedlings

Selenium (Se) plays a dual role in plant growth, functioning as both an essential micronutrient and a potential toxin. Understanding the regulatory mechanisms of Se tolerance is crucial for enhancing crop resilience and biofortification. In this study, we integrated transcriptomics (RNA-seq), chromatin accessibility (ATAC-seq), and genome-wide association studies (GWAS) to elucidate the regulatory networks governing Se responses in maize seedlings. Low Se concentrations (≤ 0.05 mM) enhanced plant growth and biomass accumulation, whereas high Se concentrations (≥ 0.1 mM) induced toxicity and suppressed growth. Different treatment groups exhibited dose-dependent transcriptional reprogramming, with significant upregulation of genes involved in glutathione biosynthesis, Se metabolism, and jasmonic acid (JA) signaling. Concurrent chromatin accessibility remodeling in promoter regions orchestrated the transcriptional responses of these key genes. Characterization of the ZmGSTs gene family revealed subfamily-specific expression patterns and regulatory mechanisms under Se stress. Integration of high-confidence transcriptional regulatory networks with GWAS data led to the identification of a key metabolic gene (ZmGSR2) in the selenium metabolism pathway and three important transcription factors (ZmWRKY48, ZmbZIP123, and ZmKNOX6) that specifically activated distinct ZmGSTs genes. This study provides novel insights into the genetic and epigenetic mechanisms underlying selenium tolerance and identifies potential targets for improving crop selenium adaptability.