The heat shock protein 40 LeDnaJ regulates stress resistance and indole-3-acetic acid biosynthesis in Lentinula edodes

DnaJ proteins, termed heat shock proteins based on their molecular weight, function as molecular chaperones that play critical roles in regulating organism growth and development as well as adaptation to the environment. However, little has been reported on their gene function in higher basidiomycetes. Here, the heat shock protein 40 (LeDnaJ) gene was cloned and characterized from Lentinula edodes. RNA interference was used to explore the function of LeDnaJ in response to heat stress and Trichoderma atroviride. Integration of the target gene into the L. edodes genome was confirmed by Southern blot analysis, and the silence efficiency of LeDnaJ was analyzed by qRT-PCR. The results revealed that LeDnaJ silence caused defects in mycelial growth and resistance to heat stress and T. atroviride, but increased the mycelial density compared with the wild type (WT) strain 5606. Additionally, the IAA content showed a more than 10-fold increase in the WT after heat stress, but an about two-fold increase in the two LeDnaJ RNAi transfortants (LeDnaJ-i-6 and LeDnaJ-i-8). Previous study has shown that enhanced IAA (indole-3-acetic acid) content enhanced the thermotolerance of the heat-sensitive strain YS3357. In this study, it was documented that IAA amendments could partly restore the resistance to T. atroviride and thermotolerance of the two LeDnaJ RNAi transformants. Overall, LeDnaJ is nvolved in fungal growth, T. atroviride resistance, and thermotolerance by regulating the IAA biosynthesis in L. edodes.