Transcriptomic and Physiological Profiling Reveals Metabolic Determinants and Key Regulatory Hubs of Fruiting Body Degeneration in Lentinula edodes

Frequent strain degeneration during subcultivation, characterized by impaired sporulation and fruiting body formation, represents a major constraint in fungal agricultural production. Our study systematically investigated two naturally degenerated Lentinula edodes strains classified as abortive (Abt: L808-13, L808-14) and malformed (Abn: L808-18) fruiting-body phenotypes, through comprehensive phenotypic characterization, enzymatic profiling, thermotolerance assessment, and transcriptomic analysis. While vegetative growth remained unaffected, degenerated strains exhibited premature hyphal knotting, significantly reduced thermotolerance, and Abn-specific suppression of carboxymethyl cellulase (CMCase) activity. Comparative transcriptomics revealed 1239 and 582 differentially expressed genes (DEGs) in Abt and Abn groups, respectively, accompanied by a global dysregulation in carbohydrate catabolism, phospholipid metabolism, and redox homeostasis. Furthermore, protein–protein interaction (PPI) networks and RT-qPCR data highlighted 12 core hub genes enriched in glycoside hydrolysis, cytochrome P450 signaling, and membrane lipid dynamics. These findings provide mechanistic insights into the molecular basis of fruiting body degeneration and establish a foundation for developing diagnostic indicators to screen for early-stage degeneration in industrial mushroom production.