The non-canonical functions of telomerase reverse transcriptase gene GlTert on regulating fungal growth, oxidative stress, and ganoderic acid biosynthesis in Ganoderma lucidum

The telomerase reverse transcriptase (TERT) is the core catalytic subunit of telomerase. Its canonical function is synthesizing telomeric repeats to maintain telomere length and chromosomal stability. Accumulating evidence suggests that TERT has other important fundamental functions in addition to its catalytic telomere repeat synthesis activity. However, the non-canonical roles of TERT independent of its enzymatic activity are not clear in filamentous fungi. In the present study, we characterized the GlTert gene in Ganoderma lucidum. The non-canonical roles of GlTert were explored using GlTert-silenced strains (Terti8 and Terti25) obtained by RNA interference. Silencing GlTert delayed the fungal growth, decreased the length between hyphal branches, and induced fungal resistance to oxidative stress in G. ludicum. Further examination revealed that the intracellular ROS (reactive oxygen species) levels were increased while the enzyme activities of the antioxidant systems (superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase) were decreased in GlTert-silenced strains. In addition, silencing GlTert decreased the ganoderic acid (GA) biosynthesis of G. lucidum. Taken together, our results indicate that GlTert plays a fundamental function on fungal growth, oxidative stress, and GA biosynthesis in G. lucidum, providing new insights for the canonical functions of TERT in filamentous fungi. KEY POINTS: • GlTert affected fungal growth and hyphal branching of G. lucidum. • Silencing GlTert increased the intracellular ROS levels of G. lucidum. • GlTert regulated GA biosynthesis of G. lucidum.