Cytology, transcriptomics, and proteomics analyses revealed selenium accumulation mechanisms and nutritional quality changes at sodium selenite in Lentinula edodes

From the paper

Abstract

Lentinula edodes is one of the most popular edible mushrooms worldwide, with remarkable potential for selenium (Se) biofortification. However, little is known about the mechanisms underlying Se stress in L. edodes. In this study, we integrated cytological, transcriptomic, and proteomic analyses to investigate the effects of varying Se concentrations (0, 300, and 500 mg/kg sodium selenite) on L. edodes across three developmental stages (mycelium, primordium, and fruiting body) and clarify the molecular basis of Se biofortification. The results showed that Se biofortification significantly enhanced biomass yield and nutritional quality of fruiting bodies, with increased accumulation of crude polysaccharides, crude protein, essential minerals (Ca, Zn, Fe), and amino acids. Notably, Se speciation varied with concentration: at low Se (≤300 mg/kg), selenomethionine (SeMet) was the predominant organic Se form, while at high Se (≥400 mg/kg), methylselenocysteine (MeSeCys) became dominant, indicating both are key organic Se compounds in fruiting bodies. Transcriptomic and proteomic analyses identified 16,665 differentially expressed genes (DEGs) and 6839 differentially expressed proteins (DEPs), with distinct expression patterns across developmental stages (exhibiting stage-specificity) and selenium concentrations (showing dose effects). KEGG enrichment analysis revealed that starch and sucrose metabolism served as the core responsive pathway: key genes (e.g., AMY, UGP2, TPS) involved in starch degradation, UDP-glucose synthesis, and trehalose accumulation were significantly upregulated. These genes not only provide energy and carbon skeletons for selenium assimilation but also enhance osmotic regulation and stress tolerance through trehalose accumulation. Additionally, DEGs and DEPs associated with amino acid metabolism (arginine, proline), lipid metabolism (glycerolipids), and selenocompound metabolism were differentially regulated across different developmental stages, which synergistically promote the synthesis and accumulation of organic selenium. Eight candidate genes, closely associated with starch and sucrose metabolism, glycerophospholipid metabolism, and arginine/proline metabolism, were identified as key regulators of Se stress response. Together, these findings elucidate the molecular mechanisms of Se biofortification in L. edodes, highlighting stage-specific metabolic regulation and core pathways underlying Se accumulation, tolerance, and nutritional enhancement, which provide a theoretical basis for developing Se-enriched functional mushrooms.