Light is an important environmental signal for various organisms to regulate their physiological and developmental processes. In fungi, light influences sexual/asexual reproductions, mycotoxin productions and pigmentation. Effects of light are obviously observed in morphological differentiations of mushrooms, and are known to be required for the initiation of fruiting body formation. The photoreceptor-encoding genes have been isolated from several basidiomycetes and genetical analyses evidenced the involvement between fruiting body formation and light. However, details of light-sensing systems and light-dependent gene regulations are still unclear.
To analyze the comprehensive change of light-stimulative gene expressions for fruiting body formation in mushrooms, we carried out super serial analysis of gene expression (SuperSAGE) by Illumina/Solexa genetic analyzer in the basidiomycetous fungus Lentinula edodes (Shiitake-mushroom). The mycelium which had been exposed to light formed a number of primordium and then could develop into normal fruiting bodies, whereas no primordium grew from the mycelium cultivated under continuous darkness. The obtained transcriptomic data showed that there were many kinds of genes expressed after light irradiation (5251 genes), compared with the data under darkness (2876 genes). Approximately, 2500 genes were differentially expressed between light and dark condition, and the transcriptions of over 2000 genes were strongly stimulated by light treatment. Light irradiation also caused the drastic decrease in the expression levels of 500 genes. The up- and down-regulated genes identified in this study were categorized and were assigned by Gene Ontology and KEGG pathway mapping. The analyzed data contained putative fungal-specific genes, whose expressions were regulated by light. The cataloged data of light-stimulative genes provide valuable information on understanding of light-sensing system essential for fruiting body formation in basidiomycetous fungi, including L. edodes.