| Tobacco Bacterial Wilt is a vascular soil-borne bacterial disease caused by Ralstonia solanancearum.It severely harms the yield and quality of tobacco and has a devastating effect on tobacco production in China.The selection and breeding of disease-resistant varieties is the most economical and effective way to solve the harm of tobacco bacterial wilt.However,there are still some problems in the study of tobacco bacterial wilt,such as lack of high-quality disease-resistant germplasm resources,unclear genetic law of resistance,and unclear genetic mechanism of disease resistance.Genetic analysis and resistance mechanism were studied with anti-green blight mutant 153-K.The main research results are as follows:1.Using the "major gene + polygene" mixed genetic model to analyze the genetic law of 153-K to tobacco bacterial wilt in Fujian and Anhui disease nurseries.The results showed that the optimal genetic model of 153-K in Anhui is MX2-EEAD-AD,that is,2 equal dominant major genes +additive-dominant polygene model;the optimal genetic model of 153-K in Fujian is MX2-ADI-AD,which is 2 pairs of additive-dominant-epistatic major gene + additive-dominant polygene model.Correlation analysis results showed that in the two disease nurseries of Anhui and Fujian,bacterial wilt resistance was significantly negatively correlated with plant height,but was not significantly correlated with leaf number,pitch,stem circumference,etc.2.Based on the materials of tobacco resistant to bacterial wilt mutants(117-K、153-K、486-K、633-K),resistant control(Yanyan 97)and sensitive control(CB-1,Changbohuang),using specific primers in literature and combined with fluorescence quantitative technology to detect colonization of Ralstonia solanacearum in root tissues of the tobacco mutant materials resistant to tobacco bacterial wilt and disease-resistant and susceptible control materials at different time points(0 d,1 d,3 d,5 d).The results showed that Ralstonia solanancearum was not detected in the root tissue of each material when Ralstonia solanancearum was not inoculated.The content of Ralstonia solanancearum in the root tissue of the mutant 117-K、153-K、486-K、633-K was lower than that of the susceptible material at different time points of inoculation with Ralstonia solanancearum.3.In this study,by using the susceptible control CB-1,Changbohuang and resistant control resistant control Yanyan 97 as the resistant control,the resistant mutant 117-K、153-K、486-K was used as the research object,the activities of CAT,PPO,SOD and POD in leaves and root tissues of tobacco resistant bacterial wilt mutants and 3 disease resistance、Susceptible control materials were measured at different time points(0 d,1 d,3 d and 5 d).The results showed that the enzyme activity of the mutant material increased to a certain extent after inoculation compared with the uninoculated.At the same time of inoculation,compared with the susceptible control material,the activity of the 4 enzymes was lower than that of the susceptible material except for some time points.Except for the disease control materials,the enzyme activities of the others were higher than those of the disease control materials.4.In this study,transcriptome sequencing was performed on tobacco root tissues at different time points(0 h,0.5 h,3 h and 24 h)using the modified resistant bacterial wilt mutant and susceptible control CB-1.A large number of differentially expressed genes were identified,and GO analysis and KEGG metabolic pathway analysis were performed on the differentially expressed genes.The results show that tobacco responds to the invasion of Ralstonia solanacearum to initiate the expression of disease resistance genes and metabolic pathways,mainly scopolane,phenylpropane biosynthesis,MAPK signaling pathway-plants,glutathione metabolism,ketone body synthesis and degradation,plant-pathogen interaction,peroxisome and other pathways.5.Six differentially expressed genes that might be associated with bacterial wilt resistance were were selected for RT-qPCR verification in CB-1 and mutant modified materials.The results showed that the evm.TU.Hic＿asm＿20.4264,evm.TU.Hic＿asm＿0.3371 domains contained WRKY transcription factors,which may be the reason for the mutant modified materials to respond to the stress of bacterial wilt. |
PDF Full Text Request