Mechanisms of formation and consumption of VSCs in thermal dehydration of Lentinula edodes: A transcriptomic analysis utilizing WGCNA

Abstract

The aroma of Lentinula edodes, primarily attributed to volatile sulfur compounds (VSCs), is a crucial factor influencing its commercial and culinary quality. This study investigated cellular activity and transcriptomic changes during gradient hot-air drying (40–60 °C) at various stages. AO/EB staining and tissue culture confirmed cell viability throughout the drying process. Transcriptomic analysis identified 4255 significantly different expressed genes (|log₂FC| > 1, p < 0.05), including 366 associated with sulfur metabolism. WGCNA, KEGG, and GO analyses revealed that glutathione synthesis and degradation were inhibited during drying. The gene LeGGT_3 (C8R40DRAFT_1158952) was identified as a regulator of γ-GTase synthesis. Five cysteine desulfurase (C-Dase)-encoding genes were enriched in the cysteine and methionine pathways, with LeNifs_3 (C8R40DRAFT_1079603) transcriptionally modulating C-Dase activity, which positively correlates with the production of cyclic thioethers (p < 0.05). The upregulation of DNA repair genes between 4 and 8 h enhanced cyclic thioethers (e.g., lentinionine). Early drying (0–4 h) suppressed methionine biosynthesis but activated cys synthesis. Compared to fresh samples, changes in sulfur assimilation genes during 6–8 h of drying consumed VSCs. The upregulation of LeNifs_3 increased C-Dase activity, thereby promoting the formation of cyclic thioethers. This study underscores the pivotal role of LeNifs_3 in the biosynthesis of cyclic sulfides in hot-air-dried Lentinula edodes, providing valuable insights for the development of high-quality mushroom products.