Functional Study Of Resistance-related Genes In The Host Flavonoid Biosynthesis Pathway After Didymella Segeticola Infected Tea Plant

As a major tea industry,Guizhou province ranks first in China.Due to its high altitude,cloudy,lack of sunshine and low temperature,the development of tea industry in Guizhou has unique advantages.While tea diseases are harmful factors limiting the healthy development of tea industry in Guizhou.The tea leaf spot caused by Didymella segeticola was firstly isolated by our research group in Shiqian County,Guizhou Province.The pathogen could infect fresh shoots,tender leaves and mature leaves of tea,which seriously affected the quality and yield of tea.However,there are no effective control measures for D.segeticola.In order to further study the resistance mechanism of tea to D.segeticola,transcriptome sequences were performed during the infection by D.segeticola.The number of the differentially expressed genes(DEGs)in the tea plant during infection,compared with control treatment,in total of 1,900 were identified in tea,of which 678 were upregulated and 1,222 were downregulated.The gene ontology(GO)and kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis revealed that there were significantly DEGs in the flavonoid biosynthesis pathway,and four DEGs were selected from this pathway: Flavonol synthase/Flavanone 3-hydroxylase(FLS/F3H),Chalcone synthase 1(CHS1),Leucoanthocyanidin reductase 1(LAR1)and Caffeoyl-Co A O-methyltransferase(CCo AOMT).The homologous genes of four DEGs were obtained from the database of the plant information archive and solanaceae genomics network,and the fragment sizes were 387 bp(FLS/F3H),1,170bp(CHS1),1,005 bp(LAR1)and 633 bp(CCo AOMT),respectively.The techniques of virus-induced gene silencing(VIGS)and transient expression were used to investigate the function of four target genes.The TRV2 expression vector and p BI121 expression vector of four target genes were constructed to observe the tobacco phenotype after silencing or overexpression,respectively.And the tobacco after silencing or overexpression were inoculated with Botrytis Cinerea for disease resistance analysis.The results showed that the diameter of tobacco spot increased after gene silencing,while the diameter of tobacco spot decreased after gene overexpression.The results showed that the function of four target genes was related to the disease resistance in tea.In this paper,the transcriptome data of tea leaves infected by D.segeticola were used to screen the key genes of flavonoid biosynthesis pathway and verify their functions,which provided new ideas for tea resistance breeding,the research on the pathogenic mechanism of D.segeticola and control measures.