CRISPR/Cas9-directed disruption of wc-2 leads to absence of fruiting body development in Pleurotus ostreatus

Light, particularly blue light, is a key environmental factor that induces fruiting in certain agaricomycetes. In this study, we characterised mutant strains of Pleurotus ostreatus with disrupted wc-2, which encodes one of the white-collar proteins, Wc-2, to investigate the role of light in fruiting in P. ostreatus. We introduced two different plasmids containing expression cassettes for Cas9 and two different gRNAs targeting wc-2 separately into the dikaryotic P. ostreatus strain PC9×#64. Among the 11 dikaryotic hygromycin-resistant transformants, 6 strains did not form fruiting bodies. Genomic PCR followed by sequencing analysis suggested that all six fruitless strains were dikaryotic wc-2 disruptants. Small aggregate structures were not observed in the dikaryotic wc-2 disruptants grown under light conditions, as in PC9×#64 grown in a red box. These results suggest that Wc-2 is essential for the initiation of blue light-induced fruiting in P. ostreatus.