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

Summary

Scientists studied a medicinal fungus called Cordyceps militaris and discovered that a protein called CmOzf acts as a master controller of several important processes. When light shines on the fungus, it activates CmOzf, which helps the fungus produce spores for reproduction through a specific genetic pathway. Interestingly, when CmOzf is blocked, the fungus produces fewer spores but makes more pigments and beneficial compounds. This discovery could help improve the production of medicinal compounds from this fungus and its use as a natural pest control agent.

Background

Cordyceps militaris is an entomopathogenic fungus that produces bioactive compounds including cordycepin, polysaccharides, and carotenoids with medicinal properties. Conidial fitness and secondary metabolite production critically influence its morphogenesis and entomopathogenicity, yet the regulatory mechanisms remain unclear. Light is known to affect fungal development through blue-light receptors, but downstream signaling components in C. militaris remain elusive.

Objective

This study investigated the role of CmOzf, a light-responsive transcription factor homologous to BbSmr1, in regulating conidiation, fruiting body development, and secondary metabolism in C. militaris. The researchers hypothesized that CmOzf integrates light signals to coordinate key developmental processes through interaction with the blue-light photoreceptor CmWC-1.

Results

Disruption of Cmozf severely impaired conidial development while increasing polysaccharide and carotenoid accumulation and accelerating fruiting body formation. CmWC-1 was upregulated in ΔCmozf mutants, while Cmozf expression was suppressed in ΔCmwc-1 mutants. CmOzf bound to promoters of both Cmwc-1 and CmbrlA, forming a feedback loop that differentially regulates conidiation versus secondary metabolism.

Conclusion

CmOzf acts as a central regulator that directly activates the conidiation pathway via the BrlA-AbaA-WetA axis and forms a feedback loop with CmWC-1 to modulate secondary metabolism and fruiting body development. This CmOzf-CmWC-1 regulatory module represents a sophisticated light-responsive mechanism coordinating fungal development and metabolism, offering genetic targets for strain improvement in biocontrol and pharmaceutical applications.
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