Comparative analysis of genome-wide transcriptional responses to continuous heat stress in Pleurotus tuoliensis

Temperature plays an impactful role in mushroom cultivation. To obtain insights of transcriptomic response in macrofungi against heat stress, we performed RNA-seq analysis using Pleurotus tuoliensis mycelium cells that were treated under 32 C-degrees and 36(degrees)C for consecutive 96 h. By comparing the growth rate data, we found mycelium cells could maintain normal growth rate almost the same as control under 32 C-degrees, yet halted the growths under 36 C-degrees. In total, 2724 differential expressed genes were identified from the three pair-wise comparisons, which were classified to four clusters based on their expression patterns. We also performed gene set enrichment analysis using both GO and KEGG databases, and revealed 48, 113 and 105 enriched GO terms, and 1, 5, and 6 enriched KEGG pathways for three pair-wise comparisons accordingly. In addition, we identified 9 overlapping GO terms and 1 overlapping KEGG pathway shared by the three comparisons. Differentially expressed genes (DEGs) involved in cell communication, amino acid metabolic process, intracellular signal transduction and small molecule biosynthesis were identified in two heat stress treatments despite of the stress intensity. However, the expression of two heat shock protein genes (HSP10 and HSP60) were induced by increasing temperature. Our findings also suggested the DEGs associated with cell cycle regulation had various expression patterns under two heat stress conditions possibly due to different functions. Furthermore, 11 DEGs related to ergosterol biosynthesis were identified with similar expression trends, indicating the ergosterol levels and cell membrane composition may have a tight connection to the acquisition of thermotolerance, which warrant further investigations for deeper understanding of molecular mechanisms in fungal stress responses.