Genetic Analysis of Resistance to Brown Spot Disease in Tobacco Cultivars Jingyehuang and Beinhart1000-1

Tobacco cultivar/line Jingyehuang, named JYH, and Beinhart1000-1, named Beinhart, have shown effective resistance to brown spot disease. In this study, populations of P₁, P₂, F₁, and F₂ were generated as experimental materials from two crosses between the two cultivars and susceptible cultivar NC82. The joint segregation analysis method of mixed major gene plus polygene genetic model was used to investigate the inheritance of resistance to brown spot disease in tobacco. The results showed that the inheritances of both JYH and Beinhart fitted to a mix genetic model of two major genes with additive-complete dominance effects plus poly-genes with additive-dominance effects (E-5 model). For high resistance material JYH, the additive effect of the first major gene was larger than the second one. For high resistance material Beinhart, the additive effect of two major genes was equal. Heritability of the major genes was 64.72% in JYH×NC82, and 63.88% in Beinhart×NC82 in F₂, indicating that resistances to brown spot disease in tobacco cultivars JYH and Beinhart were mainly controlled by major genes.