Analysis on Genes Expressed during Photomorphogenesis of the Fruiting Bodies in Pholiota nameko

Abstract

Light is required for formation of fruiting bodies in many Basidiomycetes. Action spectrum studies of fruiting-body formation in some Basidiomycete species have shown that blue light is required for formation and maturation of the fruiting bodies. However, details at the molecular level of light perception in Basidiomycetes are mostly unknown.
In this study, the genes expressed in the early and late stages of fruiting-body formation of Pholiota nameko were addressed in order to investigate the relationship between photomorphogenesis and light-regulated gene expression in the Basidiomycete. Differential display RT -PCR showed similar,but not identical profiles of genes expressed in the fruiting bodies grown under different light conditions. This result suggests that the expression of only a small number of genes is regulated by light. The cDNAs,which differed in their levels between the samples,were sequenced. Two of the cDNAs,expressed in light-grown fruiting bodies at the early stage of formation encoded the cell division control (CDC) proteins 5 and 6. RT-PCR analysis of the cdc5 homolog (Pncdc5) showed that Pncdc5 mRNA was present in the fruiting bodies grown under a fluorescent lamp or blue LED illumination but not in the fruiting bodies grown under red LED illumination or in darkness. This result represents the first demonstration that the expression of the cdc5 gene is regulated by blue light. The other cDNAs were found to encode genes involved in primary cellular functions, i.e. metabolism,cell structure and protein synthesis/degradation. These results suggest that these gene products may affect morphological appearance of the fruiting body in P. nameko.