Preliminary Study On Pathogenic Mechanism Of Colletotrichum Camelliae Based On Transcriptome Sequencing

Tea plant(Camellia sinensis(L.)O.Kuntze)is an important economic crop in China.But the growth of tea plants is threatened by a variety of diseases.Among them,anthracnose is one of the most important diseases.And Colletotrichum camelliae is the predominant pathogen casusing anthracnose in tea plants.Colletotrichum is a hemi-biotrophic pathogen which is widely distributed all over the world.The research on the infection mechanism has made good progress on other plants,however,the study of interaction between C.camelliae and tea plants is rare.In order to clarify the infection mechanism of C.camelliae and provide theoretical basis for prevention of tea anthracnose,this study analyzed the gene expression of C.camelliae at different growth stage beased on the transcriptome data analysis,and further revealed the infection mechanism of C.camelliae.The main results are as follows:1.We induced the C.camelliae to grow and form conidium(Con),Germ Tube(GT),Appressoria(App),Cellophane Infection Hyphae(CIH),Infection Leaves(IL).Then explore different methods to induce the generation of App and clarified the best way which is 1 cm2 single layer cellophane induction.2.Based on the transcriptome sequencing,a total 12820 differentially expressed genes(DEGs)were screened in this study.The DEGs of different tissues of C.camelliae were analyzed sunsequently under GO and KEGG enrichment analysis.On the basis of gene ontology(GO)enrichment analyses of differentially expressed genes(DEGs)in comparisons of germ tube(GT)/conidium(Con),appressoria(App)/Con,and cellophane infectious hyphae(CIH)/Con groups,the cellular process,intracellular,intracellular part,cell,and cell part were significantly enriched.Hydrolase activity,catalytic activity,and molecular_function were particularly enriched in the infection leaves(IL)/Con group.KEGG enrichment results indicated the DEGs were enriched in Genetic Information Processing pathway(Ribosome)at GT stage and Metabolism pathway(Metabolic Pathways and Biosynthesis of Secondary Metabolism)in the rest of the stages.3.We abalysis the genes expression pattern which involved in the process of melanin biosynthesis and Carbohydrates Active enzymes(CAZys),indicating that cAMP and MAPK signaling pathway relevant genes which associated with melanin biosynthesis were up-regulated in App,CIH,IL stages.And key genes of 1,8-DHN-denpendent melaninzation,including Polyketide synthase(PKS),1,3,6,8-tetrahydroxynaphthalene reductase 1(T4HR1),Scytalone dehydratase 1(SOD1),1,3,8-trihydroxynaphthalene reductase 1(THR1),Laccase gene 2(LAC2)were up regulated at App stage.We screened 278 DEGs of CAZys,expression analysis shown those genes were significantly up-regulated at App、CIH、IL stages.Besides,the PLs only up-regulated at IL stage.4.In this study,6 secreted proteins with unknown function-annotated were screened and identified as candidate effector proteins(CEPs).Subcellular localization results of these CEPs indicating that Cc228、Cc323、Cc533、Cc1119 located in nuclear,cytoplasmic and cytomembrane of Nicotiana benthamiana,Cc667 located in cytoplasmic of N.Benthamian a,indicating different CEPs function in different locazilation in host plant cells.In this study,the gene expression changes of C.camelliae in different growth processes were preliminarily studied from the transcriptome level.This study was the first to successfully induce the production of C.camelliae at different growth stages,and on this basis,with the help of transcriptome technology,the gene expression pattern and the infection mechanism of the fungal was clarified.The results will lay a theoretical foundation for the future breeding of tea plants for disease resistance and field disease control.