CmVVD is involved in fruiting body development and carotenoid production and the transcriptional linkage among three blue-light receptors in edible fungus Cordyceps militaris.

Fruiting body development and carotenoid production are light-induced in Cordyceps militaris. Our previous studies have shown that two blue-light receptors, CmWC-1 and CmCRY-DASH, regulate fruiting body development and secondary metabolism. However, the photosensory system of C. militaris remains unclear. Here, gene deletion of Cmvvd, coding for another blue-light receptor, resulted in reduced conidiation level and significant promotion of carotenoid content. Cmvvd transcription levels at fruiting body stages were higher than at other stages, and fruiting bodies could not develop normally in ΔCmvvd strains, indicating that Cmvvd might play an important role in fruiting body development. Rhythm loops were not affected in ΔCmvvd strains but were regulated by Cmwc-1, and the expression of the rhythm regulator gene Cmfrq was dependent on CmWC-1. Chromatin immunoprecipitation assay confirmed that Cmvvd is the direct target of CmWC-1 in this fungus. Our results also revealed interdependent transcriptional relationships between Cmwc-1 and Cmvvd, and between Cmwc-1 and Cmcry-DASH. Cmcry-DASH expression was affected by Cmvvd, and the function-loss of Cmcry-DASH might be compensated by the high transcription of Cmvvd. This is the first report of the transcriptional linkage among the three blue-light receptors in edible fungi and will be helpful for studies of multicellular development in this fungus.