| Tobacco Bacterial Wilt caused by Ralstonia solanancearum is the most serious soil-borne tobacco disease in China.Tobacco bacterial wilt is widely distributed in China,which seriously restricts the development of Chinese tobacco industry.This study aimed to identify and genetically analyze tobacco bacterial wilt resistance mutants and map resistance genes.The main mutant materials used are:486-K,633-K,117-K.First,the agronomic character measurement and field bacterial wilt resistance identification of mutant materials were carried out in Huanxi,Fujian and Xuancheng,Anhui,respectively,and a stable tobacco bacterial wilt resistance identification system was established based on the results of indoor inoculation identification.Second,field disease investigation conducted genetic analysis on the resistance of the mutants to bacterial wilt.Finally,BSA mixed pool sequencing and SNP locus detection were used to map the resistance genes of the mutants to provide materials for the development of new tobacco bacterial wilt resistance varieties and theoretical basis.The main findings are as follows:1.In 2017 and 2019,the agronomic traits of mutants 486-K,633-K and mutagenic parent Cuibi No.1 planted in Xuancheng,Anhui and Fujian,respectively were measured.The results showed that Compared with Cuibi No.1,the two mutants had shorter overall phenotypes per plant,but there was no significant change in the number of tobacco leaves（p>0.05）.The field disease survey found that the disease index of the two mutants were significantly lower than the resistance variety Yanyan 97（p<0.05）,indicating that the resistance in the field was higher than the resistance variety Yanyan 97.2.The wild type variety Cuibi No.1,the susceptible variety Honghua Dajinyuan,and the disease-resistant variety Yanyan 97 were used as control materials to identify and inoculate mutants 486-K and633-K.The results showed that the optimum concentration of Ralstonia solanacearum identified in the laboratory was 3.8×108 cfu/mL(OD600=0.3).The disease index of the two mutants was significantly lower than that resistant variety Yanyan 97（p<0.05）,it means the resistance was higher than Yanyan 97.Correlation analysis of the incidence rates in the fields of Anhui and Fujian with the results of indoor identification,the correlation coefficients were 0.915 and 0.933,respectively,which were significantly positively correlated（p<0.05）.3.Using mutagenic parent Cui Bi No.1 as the female parent and mutants 486-K and 117-K as the male parent,construct F1 and F2 populations,and analyze the population genetic effects.The results showed that the Chi-square test found that the number of disease-level strains of two mutants F2generations was normally distributed.Analysis of the mixed model of plant quantitative traits found that the optimal resistance genetic model of mutant 117-K is 2MG-A,indicating that resistance is controlled by two main genes with additive effects;the genetic inheritance of resistance of mutant 486-K is that main genes are additive,dominant,and epistatic,the model is 2MG-ADI,some epistatic effects have a greater impact,including dominant and dominant interactions.Both mutants have high heritability of major genes,78.57%and 88.34%,respectively.4.Cuibi No.1×mutant 633-K F2 population was planted in Xuancheng,Anhui,and 20 strains of extreme resistant and susceptible strains were used for BSA mixed pool sequencing trait mapping.Filtered Seven candidate resistance genes:evm.TU.Hic＿asm＿12.2330,evm.TU.Hic＿asm＿13.3107,evm.TU.Hic＿asm＿20.424,evm.TU.Hic＿asm＿20.1244,evm.TU.Hic＿asm＿20.1909,evm.TU.Hic＿asm＿20.1909,evm.TU.Hic＿asm＿23.254. |
