Regulation of fruiting body photomorphogenesis in Coprinopsis cinerea.

The agaricomycete (homobasidiomycete) Coprinopsis cinerea has been used as a model to study the molecular mechanism for photomorphogenesis. Molecular genetic analyses of mutants defective in fruiting body (mushroom) photomorphogenesis of C. cinerea identified two genes, dst1 and dst2. dst1 encodes a homolog of WC-1, a fungal blue-light photoreceptor first identified in Neurospora crassa, while dst2 encodes a novel protein with a putative flavin adenine dinucleotide (FAD)-binding-4 domain. In addition, reverse genetic analysis revealed that disruption of a C. cinerea gene encoding a WC-2 homolog, the partner of WC-1, causes the same blind phenotype. Searches on the genome data show that both WC-1 and WC-2 homologs are present in some agaricomycetes other than C. cinerea. Furthermore, in an agaricomycete, Lentinula edodes, it has been shown in vitro that the WC-1 and WC-2 homologs interact with each other. These findings suggest that the presumptive mechanism for blue-light sensing in agaricomycetes is fundamentally similar to that in Neurospora crassa, in which the WC-1/WC-2 complex plays a central role. Since the WC-1/WC-2 complex operates as a photoreceptor and a transcription factor, future studies will include identification of the targets of the WC-1/WC-2 complex that regulate photomorphogenesis in agaricomycetes. Another future challenge will be elucidation of the role of the newly identified photomorphogenetic protein, Dst2, in the blue-light-sensing mechanism.