Light-responsive transcription factor CmOzf integrates conidiation, fruiting body development, and secondary metabolism in Cordyceps militaris.

Abstract

Cordyceps militaris, an entomopathogenic fungus, produces diverse bioactive compounds. Conidial fitness and secondary metabolite levels critically influence its morphogenesis and entomopathogenicity, yet the regulatory mechanisms remain unclear. In this study, disruption of Cmozf severely impaired conidial development, significantly reducing conidial production. The Cmozf-deficient mutant (ΔCmozf) exhibited elevated polysaccharide and carotenoid accumulation in mycelia and accelerated fruiting body formation. Notably, Cmwc-1, a blue-light photoreceptor gene, was upregulated in ΔCmozf, whereas Cmozf expression was markedly suppressed in the ΔCmwc-1 mutant. Overexpressing Cmozf in ΔCmwc-1 restored conidial yield but had no effect on fruiting body development or carotenoid content. Further analysis revealed that CmOzf bound to the promoters of both Cmwc-1 and CmbrlA, whereas CmWC-1 showed no binding activity to the Cmozf promoter. These results demonstrate that CmOzf modulates conidial development via the BrlA-AbaA-WetA central regulatory pathway and influences fruiting body development and secondary metabolite production through feedback inhibition of Cmwc-1 expression. Our findings unveil novel signaling pathways linking conidiation, secondary metabolism, and fruiting body formation in C. militaris.IMPORTANCEThe light-responsive transcription factor CmOzf plays a pivotal role in regulating both conidial formation and secondary metabolite production in Cordyceps militaris, a commercially important medicinal fungus and biocontrol agent. Our study revealed that CmOzf acts as a central regulator in fungal development by (i) directly activating the central conidiation pathway via binding to the CmbrlA promoter, and (ii) forming a feedback loop with the blue-light photoreceptor CmWC-1 to modulate secondary metabolism. This newly identified CmOzf-CmWC-1 regulatory module represents a sophisticated light-responsive mechanism that differentially controls conidial reproduction and secondary metabolite biosynthesis. These findings provide crucial insights into how light signals are transduced to regulate fungal development and metabolism, offering valuable genetic targets for strain improvement in both biological pest control applications and pharmaceutical production.