Characteristics and expression of heat shock gene Lghsp17.4 in Lenzites gibbosa, a white rot fungus of wood

Small heat shock proteins (sHSPs) act as molecular chaperones that can prevent the accumulation of damaged proteins during abiotic stress, especially heat shock, but the mechanism is not clear. To study the function of sHSPs in Lenzites gibbosa, a common polypore in northern temperate forests that causes spongy white rot of broadleaf trees, under temperature stress, L. gibbosa mycelia were grown at 25 °C for 9 d, treated at 33 °C for 15, 30, 60, and 120 min before sequencing the transcriptomes. From among 32 heat shock protein (HSP) genes found in the screen of the transcriptome data, a highly expressed gene was cloned and named Lghsp17.4. RT-qPCR was used to analyze the expression of the gene Lghsp17.4 under heat shock and dye stress. Both treatments induced higher expression of Lghsp17.4 at the transcriptional level, indicating that Lghsp17.4 might function in the response to heat stress and dye degradation. We previously found that L. gibbosa generally had a heat shock reaction (HSR) during degradation of aromatic compounds, and HSPs were always produced with manganese peroxidases (MnPs) and other lignin-degrading enzymes. Therefore, we measured the activity of MnPs in L. gibbosa after 33 °C heat shock to analyze the relationship between MnPs expression and Lghsp17.4 expression. Heat shocks of 0–30 min increased MnPs activity, and the change in MnPs activity were closely positively correlated with the expression levels of Lghsp17.4 over time, indicating a potential connection and interaction between LgHSP17.4 and MnPs during the HSR in L. gibbosa. Thus, LgHSP17.4 might have a positive regulatory effect on the HSR in L. gibbosa and be a critical component of a stress resistance mechanism.