Transcriptome Analysis And Pathogenic Gene Search Of Colletotrichum Fructicola

Camellia oleifera is an important edible oil woody species in China.Anthracnose is one of the most important diseases of C.oleifera and Colletotrichum fruticola is the main pathogen of the disease.In this study,the biological characteristics and pathogenicity of C.fruticola from two population,Wuzhishan(WZS),Hainan province and Shaoyang(SY),Hunan province,were compared.Their gene expression before and after the infection on C.oleifera was analyzed by RNA-seq.The purpose of this study is to clarify the metabolic process and regulatory genes of the two populations in the later stage of infection,and to understand the evolutionary and pathogenic mechanism of C.fruticola.The results of the study are as follows:(1)The results of biological characteristics and mycelial infection test showed that there were no significant differences in mycelial growth rate,conidial yield and the number of disease spots produced after 96 h of inoculation between the two populations.However,the average diameter of lesions caused by WZS population was larger.The pathogenicity of different strains in one population is quite different.In order to avoid individual differences,the strains with the strongest and the most stable pathogenicity in each population are selected as the test strains for RNA-seq.(2)The conidia samples and lesion samples infected for 96 h were collected and sequenced.The average clean data of spore and lesion samples were 60M and 84M respectively.The average reads data blasted to reference genome were 53M(spore)and 17M(lesion),respectively.7682 DEGs were screened from SY strain,with 5280 genes up-regulated.Meanwhile,7846 DEGs were screened from WZS strain,with 5951 genes up-regulated.(3)To find the similarities and differences between two strains after 96 h infection on C.oleifera.GO and KEGG analysis showed,after infection,up-regulated DEGs in WZS group and SY group were enriched in processes or pathways related to ribosome activity.We speculated that in the later stage of infection,C.fructicola could obtain nutrients by hydrolyzing galactoside,and maintain the redox balance through the metabolism of glutamine,arginine and proline.However,the number of up-regulated genes under ribosome related metabolic pathway in SY group was significantly less than that in WZS group.Glycoprotein metabolism(GO biological process)was significantly enriched in SY group but not in WZS group.What’s more,purine metabolism and ribosome related metabolic pathways such as RNA binding translation factor activity,RNA transport,spliceosome and RNA polymerase were significantly enriched in WZS group,while SY group did not.Further study showed that 12 genes involved in purine biosynthesis and degradation were up-regulated in Wuzhishan group,but showed no expression difference in Shaoyang group.It is suggested that purine metabolism might be one of the reasons for the difference of pathogenicity between two populations.