Effects Of Exogenous Auxin And Its Analogues On Thermotolerance And Expression Of Genes Related To Heat Stress In Lentinula Edodes

High temperature affects growth and development of Lentinula edodes,one of the most cultivated widely edible fungi,even causes mycelial apoptosis or rot log,resulting in a heavy economic loss.Our previous studies documented that exogenous IAA enhanced the thermotolerance of L.edodes heat-sensitive strain YS3357,and high temperature improved significantly free IAA content in L.edodes,demonstrating that auxin could involve in alleviating the oxidative damage generated by high temperature,and play an important role during heat stress process.In this study,the heat-sensitive strain YS3357 was treated as the tested material.Comparing mycelial biomass and oxidordeuctase activities whether exogenous auxin and analogues were added or not,the effect of IAA and auxin analogues?NAA and2,4-D?on mycelial thermotolerance and biomass as well as oxidation-antioxidation system was analyzed.Transcriptomic technique was performed to explore preliminarily the regulation mechanism of auxin analog 2,4-D on L.edodes thermotolerance.In the presence of suitable concentration IAA,NAA or 2,4-D,L.edodes mycelia subjected to heat stress of 24 h could recover growth at 25?,but no growth observed in control group.It was documented that IAA,NAA or 2,4-D could improve obviously the thermotolerance of the heat-sensitive strain YS3357.In terms of hyphae recovery growth rate,2,4-D improved heat resistance better than IAA and NAA,but IAA and NAA could improve significantly L.edodes biomass.The analysis shows that exogenous auxin and auxin analogues could suppress the generation of O^2-,decrease the activity of LOX and the content of TBARS,and improve the activity of SOD,which has relations with alleviating the effect of oxidative damage induced by heat stress on the mycelia of L.edodes.L.edodes heat-sensitive strain YS3357 was cultured into the medium in presence or absence of 2,4-D,and cultured at room temperature for 9 days,and then treated at room temperature?25°C?,and high temperature?40°C?.The comparative transcriptome analysis showed that under different temperature conditions,there were 7 differentially expressed genes at room temperature?25°C?,and 11 at high temperature?40°C?.Besides,genes response to heat stress were had difference in presence or absence of 2,4-D.After heat stress,1369 DEGs were identified without the addition of 2,4-D,while there were 2468DEGs in the presence of 2,4-D.Furthermore,qRT-PCR were performed to verify transcript levels of DEGs related to auxin biosynthesis pathway and heat shock protein family,and response to heat stress.This study not only contributes to reveal and explain the effect of auxin on response to heat stress,but also possesses important scientific significance and practical value.