Molecular mechanism underlying cadmium tolerance differentiation in Lentinula edodes as revealed by mRNA and milRNA analyses

Lentinula edodes is an important candidate for heavy metal mycoremediation. This study explored the molecular mechanism of cadmium (Cd) tolerance differentiation of L. edodes through comparative mRNA and milRNA analyses of two strains, YS45 (Cd sensitive) and YS119 (Cd tolerant). Results showed the emergence of more possible protein aggregates in YS45 than in YS119 under Cd stress. The number of differentially expressed genes (DEGs) and milRNAs (DEMs) was identified as 2036 and 370 as well as five and three in YS45 and YS119, respectively. Comparison of DEGs and DEMs between the two strains revealed that genes and milRNAs involved in cell wall remodeling, transport, heavy metal chelation, lipid and carbohydrate metabolism, transcription regulation, redox homeostasis, proteolysis, signaling, DNA repair, cell cycle, may play important roles in Cd stress response, and their different expression patterns, especially those associated with proteolysis and carbohydrate metabolism, might lead to Cd tolerance differentiation between the two strains. The function of the α-amylase gene LeAmy in enhancing Cd tolerance in L. edodes was further verified by overexpression. This study has shed light on the molecular mechanism of Cd tolerance differentiation in L. edodes, and laid a foundation for breeding elite strains for heavy metal mycoremediation.