Stage-Specific Proteomic Insights into the Lignocellulolytic Machinery Associated with the Edible Fungus Lentinula edodes

Lentinula edodes (Berk.) Pegler, also known as Shiitake, is one of the most popular edible mushroom species containing high contents of polysaccharides, proteins and unique aroma, widely cultivated in China, Japan and Korea. A series of studies has been carried out on the extraction and active effect of the L. edodes polysaccharides, but the molecular mechanisms involved in the protein expression profiles during the whole life cycle are relatively unclear. This study employed an iTRAQ-MS/MS proteomic approach, combined with real-time quantitative PCR (qRT-PCR) and enzyme activity assays, to systematically analyze the protein expression profiles and their relationship with lignocellulose degradation in L. edodes across four key developmental stages: mycelia (SF), brown film formation (BF), primordia (YF), and fruiting bodies (MF). A total of 2043 proteins were identified, with 1188 being differentially expressed proteins (DEPs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that metabolic processes, carbohydrate metabolism, and related pathways were significantly active during development. The study specifically focused on carbohydrate-active enzymes (CAZymes), identifying 197 CAZyme proteins classified into 78 families. Key families such as glycoside hydrolases (GHs) and carbohydrate esterases (CEs) played crucial roles in lignocellulose degradation. The enzymatic activities of major lignin-degrading enzymes (laccase, manganese peroxidase, and lignin peroxidase) were dynamically regulated across the developmental stages. qRT-PCR results largely corroborated the proteomic data, confirming the reliability of the protein expression profiles. This study provides a comprehensive, stage-resolved proteomic landscape of lignocellulose degradation during L. edodes development, revealing species-specific temporal dynamics, offering a valuable basis for understanding its growth and development, with implications for edible fungus cultivation and biomass conversion applications.