Differential CAZymes Genes Expression Among The Monokaryons And The Dikaryon Of Flammulina Velutipes

In this study,the Carbohydrate-Active Enzymes encoding genes(CAZymes)were firstly annotated in Flammulina velutipes,based on the de novo genome sequence.The distribution and number of CAZymes of F.velutipes were compared with other 16 fungi.Further,based on the transcriptome sequencing,the transcription levels of CAZymes encoding genes were investigated between two monokaryon strains(L11 and W23)and a dikaryon strain(1123,which hybridized by the two monokaryons)in F.velutipes.Next,the activities of three major substrate degradation enzymes including cellulase,hemicellulase and ligninase were also detected in three strains under addition of several different inducer substrates as carbon source.There are 552 genes encoding CAZymes in total in F.velutipes genome,of them223 encodes Glycoside Hydrolases(GH),106 Carbohydrate Esterases(CE),81 Glycosyl Transferases(GT),21 Polysaccharide Lyases(PL),80 Auxiliary Activity Enzymes(AA)and 41 with Carbohydrate-Binding Module(CBM).The result showed that F.velutipes is predominant in the number of CAZymes encoding genes,compared with other wood rotting fungi.Especially in the number of cellulase encoding genes,F.velutipes rank the third,following after P.Chrysosporium and C.Putasna.And,the number of pectin degrading enzymes in F.velutipes was the highest among the 17 investigated wood rotting fungi,followed by P.Strigosozonata and S.commune.In addition,F.velutipes also abounds in members of auxiliary activity families AA3 and AA7(lignin degradation),and glycoside hydrolases families GH105(pectin degradation),GH43(hemicellulose and pectin degradation),GH13(starch degradation),and polysaccharide lyases families PL1 and PL3(pectin degradation).The transcriptome sequencing was performed among the two monokaryons(L11 and W23)and the dikaryon(1123)of F.velutipes,in order to compare the differential expression of CAZymes encoding genes in three strains.The results showed that there were 10094,9849 and 9432 genes expressed in 1123,L11 and W23,respectively.It was detected that there were 10629 genes expressed in three strains.Among them,9136 genes were found to be co-expressed in the three strains with a few genes specifically expressed only in one of the three strains.The analysis of the differential expression of CAZymes encoding genes between monokaryon and dikaryon showed that the number of up-regulated genes encoding CAZymes in dikaryon were more than those of down-regulated genes.In addition,the 11 types of inducers were screened to be used as only carbon source to culture mycelia of three strains of F.velutipes,in order to investigate the different degradation ability of monokaryon and dikaryon under different substrate.The results showed that the cellulase activities(filter paper enzyme and CMC enzyme activities)of dikaryon is higher under the inducing of Avicel,cellulose powder and rice straw than any one of two monokaryons.Differentially,under the the other inducers(no inducer,glucose,CMC,cellobiose,a-lactose,microcrystalline cellulose,filter paper,and cork dust),the cellulase activity of dikaryon is almost equal with monokaryon L11 or W23.The hemicellulase activity was the same with cellulase activities(exoglucanase and β-glucanase activities),the inducer abilities of all inducers were approximately the same.The laccase activity exhibited the consistent pattern under all the five inducers(microcrystalline cellulose,Avicel,filter paper,rice straw and cork dust)that dikaryon is predominant that any one of two monokaryons,only 5 kinds of inducers were detected the laccase activity,none was detected in other inducers and induced before.This study firstly investigates that different carbon substrates produce different inducing effect on the substrate degradation enzymes activity between monokaryons and dikaryon of F.velutipes using both transcriptome sequence and enzymes activity detection which provide the basis on improving or increasing the ability of substrate degrading of F.velutipes,and make a theoretical foundation for analyzing the degraded ability and improving the biological conversion of F.velutipes.