Study Of Molecular Markers Resistance Genes Of Tobacco Bacterial Wilt

Tobacco is an important economic crop, and the leaves were harvested for use. The quality of tobacco leaf is the main factor that affects cigarette industry. Tobacco diseases and pests have seriously affected the leaf quality, especially bacterial wilt. They has spread from south area of tobacco production to north area. The bacterial wilt can cause tobacoo plants death when it is very seriously. Wide range of incidence and severe diseases restrict the development of tobacco production in our country.Bacterial wilt of tobacco research is focused on tobacco, especially in China, while few on oriental tobacco.We made twelve hybrid combinations by the way of diallel cross method, using four tobacco varieties: Xanthi, kokubu, Samsun and Jiaonan Oriental tobacco as parents. Xanthi and kokubu are nosotropic, while Samsun and Jiaonan are susceptible. The research was carried out using major gene and polygene inheritance model and SSR molecular maker. The main results were as follow:(1)The cross Xanthi and Samsun were analyzed using major gene plus poly-gene mixed inheritance model. Results indicated that Bacterial wilt resistance of Oriental tobacco was controlled by two independent major genes with additive-dominance-epistatic effects+polygenes with additive-dominance effects (the E-1 model). Heritability values of the major genes were estimated as 49.63%. Results of the cross Xanthi and Jiaonan Oriental tobacco indicated that resistance gene meet the E-2 model that was controlled by two independent major genes with additive-dominance effects+ polygenes with additive-dominance effects. Heritability values of the major genes were estimated as 37.3%.(2)40 pairs polymorphic primers were scanned by bulked segregant analysis(BSA) to the segregation posterities of Kokubu×Jiaonan. A pair of SSR primer was selected which name was 2303. The maker was closely linked with disease-resistant gene, and the genetic distance is 8.73cM. Another 3 pairs primers were also scanned to the segregation posterities of Xanthi×Samsun. But the genetic distances were 20 - 30 cM.. The genetic distances were so distant that their usefulness is less.