Research Of Sterol Synthesis Pathway And Its Responses To The Stipe Elongation In Flammulina Velutipes

Flammulina velutipes is one of the main cultivated edible fungi which is the third largest edible fungus.Characterized by the slender stipe,It is an ideal research material for the research of elongation mechanism of the stipe.Ergosterol are essential lipid components of fungal membrane and have been shown that they played an important role in regulating membrane fluidity,integrity and permeability,infulcencing the function of membrane protein,and altering cell growth rate.Based on the data of F.velutipes genome and transcriptome,The bioinformatics method and Real-time quantitative PCR was used to analyze the protein properties and examine the expression of ergosterol biosynthetic pathway on the elongation stipe to explore the mechanism of the pathway in response to the elongation of the stipe.The follow results show:(1)20 ERG genes related to ergosterol synthesis pathway were screened and named based on the genome and transcriptome.The analysis of the gene structure showed that the length of each gene was within 3000 bp,similar to Saccharomyces cerevisiae.There are many introns,and transcript splicing of retain intron retention ubiquity in the introns of the gene sequences,providing a variety of transcripts for the changable biological environments.(2)The bioinformatics analysis of ergosterol synthesis pathway showed that the proteins in pathway was stably exist in the plasma membrane and endoplasmic reticulum,they had multiple transmembrane structures which played an essential role in the synthesis and transportation of the intermediates.The conserved domain analysis indicates that many proteins contain FAD-binding domain、FA_hydroxylase domain and Cytochrome P450 domain to participate in the synthesis process through the oxidative dehydrogenation reaction and sterol synthesis reaction,and the protein function of each component on the pathway is related to synthesis of plasma membrane.Phylogenetic analysis shows that these genes are relatively conserved,but vary in animals,plants and fungus.The pathway proteins showed high homologus with Coprinopsis cinerea and Trametes versicolor.(3)The expression of sterol synthase genes with differerents treatments was detected by RT-qPCR.The results showed that these genes have significant differences in different segments of stripe,the elongation region got the highest expression.we found the friuting body bent up and the expression of lower parts of bending tissue were higher than the upper when cultivated the cultivated bag with horizon.Compared with the transcriptome of these samples,Most of the results were consistent with the RT-qPCR results,make further demonstrating that these gene expression is associated with tissue elongation.All these results conducts that the ergosterol synthesis pathway losely correlation with the elongated segment.As a constituent of the plasma membrane,ergosterol synthesis pathway were activated to help expanding membrane satisfy the cell elongation and plays an important role in responding to the elongation mechanism of the stipe.