Ranscriptome Sequencing Analysis Of Sunflower Responsive To Verticillium Dahliae Infection Nad Mining Of Resistance-related Genes

Sunflower(Helianthus annuus L.),an important oil crop and ornamental plant,is also considered as a potential biodiesel source.However,Sunflower Verticillium Wilt(SVW)is threatening the industry.In order to accelerate breeding progress,it is necessary to further study the molecular mechanisms of SVW,to find important genes and biological pathways related to the resistance.The research on molecular mechanism of resistance to SVW develops slowly for a lack of disease resistance materials and genetic information.In this study,physiological and biochemical indexes were analysized in S18 and P77 inoculated by Verticillium dahliae.Furthermore,16 samples that were infected by the pathogen in different time were sequenced by RNA-Seq.And a great deal of transcriptome information about sunflower infected with V.dahliae was obtained.And then,the study on interaction mechanism of Sunflower and SVW was made by bioinformatics methods.Based on the RNA-seq data,a lot of differentially expressed genes(DEGs)were detected by examining from different pairwise transcriptome comparisons.Disease resistance related DEGs were obtained by GO(Gene Ontology)enrichment analysis.Based on the Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis and correlation network analysis,the resistance mechanism of sunflower was explored.In general,based on the transcriptome profiling results,a detailed discussion on the transcripts about the crosstalk between sunflower and V.dahliae was provided,which was beneficial to disease-resistance breeding for sunflower.The result of the study is summarized as follow:Firstly,in order to study the physiology and biochemistry mechanism of sunflower against Verticillium Wilt,some indexes were measured for 16 samples collected over a time course(0,6,12 and 24 h,and 2,3,5 and 10d post inoculation).The result showed that the content of soluble protein,the activities of POD and SOD in S18 were significantly higher than that in P77 at some time points.For MDA measurement,the content was slightly higher in P77 than that in S18 at four initial time points.Therefore,S18 could use multiple pathways to resist the infection of Verticillium wilt to protect the cells from injury.Secondly,16 sunflower RNA samples were sequenced and 110571 Unigenes were obtained after the raw reads processing by bioinformatics method.Furthermore,few kinds of software(Such as BLAST)were used for functional annotation for all Unigenes in every sample.Among all Unigenes,52406 Unigenes were categorized into 55 Gene Ontology(GO)terms;46676 Unigens were mapped to 128 canonical KEGG pathways;32215 Unigenes were subjected to 25 Clusters of Orthologous Groups(COG)families.Thirdly,in RD,SD and D datasets,1231 genes associated with SVW resistance were obtained by GO enrichment analysis in a genotype-common transcriptional pattern.While in a genotype-specific transcriptional pattern,759 and 511 genes were obtained by GO enrichment analysis in S18 and P77 respectively.Many of the genes regulated some enzymes related to resistance,such as peroxidase(POD),glutathione peroxidase,aquaporin PIP and chitinase.Forthemore,those genes play a key role in the interaction between plant and pathogen.Lastly,Lastly,KEGG analyses of the DEGs related to the resistence showed showed that 98,112 and 52 genes were classified into plant hormone signal transduction,plant-pathogen interaction and flavonoid biosynthesis categories,respectively.Many crucial points in the KEGG pathways were positively correlated with plant disease resistance,such as CNGC,RBOH,MYC2 NPR1 and TGA.The encoding genes were up-regulated in both genotypes.Notably,the expression levels of the genes in S18 were remarkably increased when comparing them with those in the P77.Some crucial points were negatively correlated with plant disease resistance,such as FLS2 and JAZ.The gene encoding FLS2 were down-regulated in both genotypes.And the expression levels of the genes in S18 were highly decreased than those in P77.All of the genes encoding JAZ were up-regulated in P77,while two genes were down-regulated in S18.Further study showed that some differentially expressed unigenes involved in abscisic acid(ABA),ethylene(ET),the salicylic acid(SA)and jasmonic acid(JA)-mediated signal transduction pathway.