Comparative Proteome Reveals Metabolic Changes during the Fruiting Process in Flammulina velutipes

Understanding the molecular mechanisms regulating the fruiting process in macro-fungi, especially industrially cultivated mushrooms, has long been a goal in mycological research. To gain insights into the events accompanying the transformation of mycelia into fruit-bodies in Flammulina velutipes, proteins expressed characteristically and abundantly at primordium and fruit-body stages were investigated by using the iTRAQ labeling technique. Among the 171 differentially expressed proteins, a total of 68 displayed up-regulated expression levels that were associated with 84 specific KEGG pathways. Some up-regulated proteins, such as pyruvate carboxylase, aldehyde dehydrogenase, fatty acid synthase, aspartate aminotransferase, 2-cysteine peroxiredoxin, FDS protein, translation elongation factor 1-alpha, mitogen-activated protein kinases (MAPKs), and heat-shock protein 70 that are involved in carbohydrate metabolism, carotenoid formation, the TCA cycle, MAPK signaling pathway, and the biosynthesis of fatty acids and branched-chain amino acids, could serve as potential stage-specific biomarkers to study the fruiting process in F. velutipes. Knowledge of the proteins might provide valuable evidence to better understand the molecular mechanisms of fruit-body initiation and development in basidiomycete fungi. Furthermore, this study also offers valuable evidence for yield improvement and quality control of super golden-needle mushroom in practice.