Hydrogen sulfide, a novel small molecule signalling agent, participates in GAs biosynthesis under heat stress and the regulation of multiple signaling pathway genes in Ganoderma lucidum

As one of the most important environmental factors, heat stress (HS) has been found to affect various biological activities of organisms such as growth, signal transmission, primary metabolism and secondary metabolism. Ganoderma lucidum has become a potential model system for evaluating how environmental factors regulate the secondary metabolism of basidiomycetes. Previous research showed that HS can induce the biosynthesis of ganoderic acids (GAs). In this study, we found the existence of hydrogen sulfide in Ganoderma lucidum; moreover, HS increased GAs biosynthesis and could affect the hydrogen sulfide content. We found that sodium hydrosulfide (NaHS), an exogenous donor of hydrogen sulfide, could revert the increased GAs biosynthesis elicited by HS. This result indicated that an increased content of hydrogen sulfide, within limits, was associated with HS-induced GAs biosynthesis. Our results further showed that the GAs content was increased in CBS-silenced strains and could be reverted to WT strain levels by the addition of NaHS. Transcriptomic analyses indicated that that H2S can affect various intracellular signal pathways and physiological processes in G. lucidum. Further studies showed that H2S could affect the intracellular calcium concentration and thus regulate the biosynthesis of GAs. This study demonstrated that hydrogen sulfide is involved in the regulation of secondary metabolic processes induced by heat stress in filamentous fungi. G. lucidum mRNA profiles of wild type (WT) and CBS-silenced strains were generated by deep sequencing, in triplicate