Overexpression of Po-cat1 Influences the MAPK Signaling Pathway by Inhibiting H2O2 Production and PoPTP1 Transcription, Thereby Affecting the Fruiting Development of Pleurotus ostreatus

Fruiting body development critically affects yield and cultivation efficiency in edible mushrooms. Although catalase (CAT) is essential for development across various organisms, its function in edible mushrooms remains poorly understood. This study investigated the function of catalase in Pleurotus ostreatus fruiting body development and identified Po-cat1 as the key gene. Increased Po-cat1 transcription raised total CAT activity and lowered intracellular H2O2 level. H2O2 acts as a positive signal for fruiting, and Po-CAT1 negatively regulates this signal by reducing H2O2, thereby inhibiting development. Transcriptome analysis revealed that the change of Po-cat1 expression altered gene expression profiles in the MAPK pathway and affected PoPTP1 transcription, possibly via H2O2. PoPTP1 promoted fruiting body development. Its overexpression reduces protein phosphorylation levels in the MAPK pathway in mycelium and fruiting body stages but increases them in primordium stage. These findings demonstrate the primary role of Po-CAT1 in P. ostreatus fruiting body development.