Improving the Characteristics of Fruiting Bodies in Lentinus edodes: The Impact of Rolipram-Induced cAMP Modulation

Background: Strains XG04 and XGT2 of Lentinus edodes (Berk.) Singer demonstrate a high degree of genomic similarity, with XGT2 representing a systematic selection of XG04 and exhibiting enhanced phenotypic traits. Methods: An investigation into the differences between these strains was conducted using untargeted metabolomics to identify potential causal factors. Five exogenous inducers were assessed for their relationship with the observed phenotypes, and their impacts on fruiting body characteristics were analyzed. Results: Notably, the exogenous inducer rolipram, at a concentration of 0.4%, was found to increase cAMP expression levels in L. edodes primordia, which subsequently affected gill development, leading to the formation of gill-free fruiting bodies. Morphological differences between the two strains were evident; XG04 exhibited a spherical morphology with absent gills, rendering it commercially unviable, whereas XGT2 displayed a thicker cap and a more robust stipe, maintaining its characteristic umbrella shape. Conclusions: As the concentration of rolipram increased, both cap retraction and gill reduction in XGT2 occurred in a dose-dependent manner. The endogenous cAMP levels in the fruiting bodies were measured before and after rolipram treatment, revealing that the cap retraction and gill reduction in XGT2 progressed in a dose-dependent manner alongside increasing cAMP expression levels. Furthermore, a positive correlation was observed between cAMP levels and rolipram concentration. This study provides a foundation for improving the quality and productivity of mushroom cultivation by manipulating fruiting body characteristics through external stimuli.