Functional Analysis Of The Role Of Glutathione Peroxidase(GPx)in The ROS Signaling Pathway,Hyphal Branching And Regulation Of Ganoderic Acid Biosynthesis In Ganodermalucidum

Ganoderma lucidum,a hallmark of traditional Chinese medicine,has been widely used for its pharmacologically active compounds.Although numerous research studies have focused on its pharmacological mode of action,fewer studies have explored its basic biological features,restricting further development and application of this important mushroom.Glutathione peroxidase(GPx)is one of the most important antioxidant enzymes with respect to ROS.Although studies in both animals and plants have suggested many important physiological functions of GPx,there are few systematic research reports on its role in fungi,especially in large basidiomycete fungi.In this study,we cloned the gpx gene and created GPx-silenced strains by downregulating gpx gene expression using RNA interference.The results indicated an essential role of GPx in controlling the intracellular H2O2 content as well as in hyphal branching,antioxidant stress tolerance,cytosolic Ca2+levels and ganoderic acid biosynthesis.Further mechanistic investigation revealed that GPx also can be regulated by the intracellular ROS levels.Moreover,evidence was obtained that GPx regulation of hyphal branching via ROS might be independent of Ca2+levels.Further mechanistic research also revealed that the effects of GPx on ganoderic acid synthesis via ROS are regulated by cytosolic Ca2+ levels.Taken together,these findings indicate that GPx-regulated ROS have a complex influence on growth,development and secondary metabolism in fungi.Our research provides an excellent framework to identify GPx functions and its role in the ROS regulation,which is very meaningful for the further development of the ROS signaling pathway.