关键词: 偏肿革裥菌, 白腐菌, 转录组, 木质素, 降解

Abstract: [Objective] The aim of this study is to provide a support for the study on the mechanism of wood degradation by Lenzites gibbosa (white-rot fungi) by sequencing the transcriptomes of white-rot fungus under woody and non-woody environments.[Method] High-throughput sequencing technology was used to sequence transcriptomes of mycelial samples of L. gibbosa with sawdust and non-sawdust treatments. The transcripts were compared and analyzed using such as eggNOG annotations, GO annotations, and KEGG annotations to predict and screen genes associated with wood degradation. Fluorescence quantitative PCR (qPCR) was used to detect the expression quantities of eleven genes such as mnp2 related to lignin degradation under 5 days of sawdust treatment, and the transcriptome data were used to analyze the genes' expression levels.[Result] A total of 38.9 Gb clean data were obtained from the transcriptome sequencing of L. gibbosa. The average clean data of each sample reach 6.49 Gb. The mapped ratio between the reads of each sample and the reference genome ranged from 71.23% to 74.25%. The edgeR software was used to analyze the genes' differential expression, and the results showed that 898 differentially expressed genes (DEGs) were obtained, among which 351 genes were up-regulated and 547 genes down-regulated. There were 251 genes annotated by GO database, 223 genes by KEGG database, and 704 genes by eggNOG database. eggNOG analysis showed that the expressions of DEGs were mostly clustered under the functional classifications of energy production and conversion, post-transcriptional modification, protein metabolism, chaperone relationship, biosynthesis of secondary metabolites, carbohydrate transport and catabolism. GO analysis showed that the significantly enriched biological processes with higher frequency were pyruvate metabolic process, isoprenoid biosynthetic process, aspartate family amino acid metabolic process and lignin catabolic process. In KEGG pathway analysis, the DEGs were distributed in 86 different biological pathways, and the major metabolic pathways with significantly enriched DEGs were carbon metabolism, citrate cycle, degradation of aromatic compounds, and glyoxylate metabolism. The result of qPCR showed that under the sawdust treatment the expressions of mnp2, mnp3, lip9, lip2, laccase1, and nadp were significantly up-regulated, and the expressions of mnp10s, mrp, cyp450-1, GroES1, and GroES2 were significantly down-regulated. qPCR and transcriptome sequencing showed that there was slight deviation in the difference multiples of expression, but the overall trend was consistent, which proved that transcriptome sequencing result were correct and reliable.[Conclusion] The wood degradation by L. gibbosa of is closely related to the pathways of carbon metabolism, degradation of aromatic compounds, and other biological processes such as lignin catabolic process. According to the result of genes functional annotation, 11 important differentially expressed genes related to the lignin degradation by white rot fungi were obtained.

Key words: Lenzites gibbosa, white rot fungi, transcriptome, lignin, degradation