Research Of The HOG Pathway Responses To Cold Shock In Flammulina Velutipes

Flammulina velutipes,is an edible and medicinal mushroom,which can fruit in winter.Its low-temperature response mechanism is unclear.In order to study the mechanism of low temperature induction on fruiting body of Flammulina velutipes,we identified homologous genes of the HOG-MAPK pathwayof the Saccharomyces cerevisiae which can sense and respond to cold.For this we used bioinformatics tools,including BLAST search of the Flammulina velutipes genome,gene alignments,and transcriptome analysis.By studying the cold sensing mechanism,our work can provide information for genetic improvement of Flammulina velutipes strains.This can reduce its energy consumption of industrialized cultivation.The results indicate that Flammulina velutipes contains important parts of the HOG-MAPK signaling pathway as found in yeast.The Flammulina velutipes HOG-MAPK signaling pathway includes a two-component signal transducer system(2CHK,FvYpdl,FvSskl and FvSkn7),the MAP kinase cascade(FvSsk2,FvPbs2A,FvPbs2B and FvHogl)and a series of downstream transcription factors(FvGpdl,FvGlo1,FvHspl2,FvSko1,FvSfal and FvTsal).The identified genes and theirs predicted proteins were analyzed for conserved domain,by phylogenetic analysis,and basic protein function prediction.All confirmed genes were constructed into a HOG-MAPK pathway for Flammulina velutipes.Moreover,analysis of promoter elements of the HOG-MAPK genes from Flammulina velutipes supported the possibility that several of these genes could be activated in response to cold stress.Next,we used the RT-qPCR to detect the gene expression levels of the Flammulina velutipes HOG-MAPK pathway genes when the mycelium was exposed to cold stress.The results showed that several genes of the HOG-MAPK pathway in Flammulina velutipes were indeed induced by the cold shock.There is a significant response within 30 minutes,followed by a return to pre-cold gene expression levels.Comparative analysis of the gene expression level under different cold temperatures invariably indicated a quick response winthin 30 minutes.In addition,the FvGpdl and FvHsp12 gene expression levels,genes that are also induced by the HOG-MAPK pathway,were significantly increased.These are a key enzyme for glycerol synthetic and small heat shock protein,respectively.Taken together,the results showed that there exists a HOG-MAPK pathway in Flammulina velutipes,and that this pathway responds to cold stress.