Comparative analyses of gene expression based on transcriptome data in different laccase activities of monokaryotic mycelia of Lentinula edodes

Abstract

Laccase plays a primary role in the lignin-degrading ability of Lentinula edodes and exerts significant influence on the quantity and qualities of products. To elucidate comprehensive transcriptional profile in the high laccase-producing monokaryotic mycelium, the transcriptome sequencing was performed and a total of 15 522 genes was annotated from the two levels of laccase activity of L. edodes strains. GO (gene ontology) analysis indicated that differentially expressed genes (DGEs) were mass-enriched in oxidoreductase activity, including the genes related to lignin-degrading enzymes and cytochrome P450 genes. KEGG (Kyoto encyclopedia of genes and genomes) pathway analysis revealed that the DGEs were significantly enriched in starch and sucrose metabolism and pentose and glucuronate interconversions including the genes encoding glycoside hydrolase and UDPG dehydrogenase, which were specifically up-regulated. 172 DGEs encoding transcription factors identified by searching the database led to the prediction of bZIP, C2H2 and C4 subfamilies probably binding with the laccases genes. The transcriptome results suggested that the alteration of gene expression involved lignin degradation and carbohydrate metabolism, in particular the up regulation of genes involved in pentose and glucuronate pathway, resulting in the high-efficiency bioconversion of lignin-degrading products provided as nutrient to promote the L. edodes growth. Transcription factors might have a crucial role in the regulation of laccase activity. This study provides critical genetic data for further understanding the metabolic mechanism of the high-yielding laccase activity monokaryotic strain.