Morphological and transcriptomic analysis revealing morphological variations and genetic clues in one Lentinula edodes abnormal browning strain

Strain abnormal browning is a common problem during cultivation of Lentinula edodes. In this study, the L. edodes strain mycelia isolated from Le-WB and cultured on MYG (Le-WP) isolated from an abnormal browning bag was compared with its normal control mycelia isolated from Le-BB and cultured on MYG (Le-BP). The aerial hyphae of Le-WP were white, and the hyphal growth was significantly reduced. Morphological observation of Le-WP under scanning electron microscope (SEM) and transmission electron microscopy (TEM) revealed abnormal organelle structures. Through transcriptomic analysis, more differentially expressed genes (DEGs) were expressed in the metabolic process and catalytic activity in Le-WP than Le-BP. Two Kyoto encyclopedia of genes and genomes (KEGG) pathways named pentose and glucorunate interconversions, and starch and sucrose metabolism were found to be enriched in Le-WP. The gene expression profiles involved in these two pathways were further analyzed and 12 key genes were selected to be verified by quantitative real-time PCR (qRT-PCR), and the results showed that most of these genes were upregulated in Le-WP. Additionally, the content of 1,3-beta-glucan in Le-WP was also significantly higher than in other samples. This research suggests that abnormal strains may be related to the abnormal synthesis of 1,3-beta-glucan, and it needs further research. This research exhibits possible morphological and genetic clues of Le-WP and lays the foundation for understanding the degeneration of L. edodes strains.