Function analysis of HMG-box transcription factor lelcrp1 in Lentinula edodes

Abstract:

[Objective] The objective of this study was to analyze the function of the HMG-box transcription factor LELCRP1 (Lentinula edodes lignocellulase genes regulation protein 1) in the expression of lignocellulase genes.[Methods] The RNAi vector of lelcrp1 was constructed by double-joint and homologous recombination, then transformed into the mycelia of Lentinula edodes heterotypic strain W1 by Agrobacterium tumefaciens-mediated transformation (ATMT). The copy number of the inserted fragment in the genome of strain W1 was detected by Southern blotting. Fluorescent quantitative PCR was used to detect the expression level of lignocellulase genes in RNAi transformants, and the mycelial growth rate was measured on MYG plates.[Results] We got four RNAi transformants which were significantly down-regulated by 6 to 7-fold compared with the original strain W1. The results of Southern blotting showed that the lelcrp1 gene fragment had been successfully integrated into the genome of Lentinula edodes in a single copy. Analysis of expression profiles of 26 lignocellulase genes in two RNAi transformants revealed that 9 cellulase genes, 1 hemicellulase gene, 2 auxiliary enzymes AA9 gene and 1 manganese peroxide gene were down-regulated significantly, compared to the original strain. The mycelial growth rate of RNAi transformants were significantly slower than the original strain.[Conclusion] The expression of lelcrp1 was silenced successfully by RNAi, resulting in down-regulation of the expression level of some cellulose and ligninase genes. The HMG-box domain transcription factor could regulate the expression of lignocellulase genes.