QTL Analysis Of The Resistance Gene To CMV In Flue-cured Tobacco

Tobacco is an important economic crop that plays a vital role in national economy. Cucumber mosaic virus (CMV) is one of the most serious diseases and is epidemics worldwide in tobacco, as well as in China, resulting in mosaic and dwarf plants and then causing the substantive loss of tobacco production. However, It is hard to control because that aphids and sap friction spread this disease. So exploring resistant-association genes and developing resistant varieties are the most effective methods.In this research, the BC1segregation population generated from the CMV resistant parent Taiyan-8and the susceptive parent NC82, was used to analyze disease resistance-association genes that is linked to the main effect QTLs after inoculation identification, we aims to find the disease resistance-association genes and lays a solid foundation for cultivating the high quality disease resistance varieties. The main results are as follows:1. It is reported that the incidence of mosaic leaves; taunted leaf bases, stunted roots and dwarfed plant were higher in the susceptive tobacco after inoculation identification seedlings of F1, F2, and BC1segregation population. The disease index of Taiyan-8was14, high resistant to CMV; the disease index of NC82was70, high susceptible to CMV; while F1was45, moderate susceptible to CMV. From the virus test results we know that segregation ratio of F2and BC1didn’t meet the Mendelian inheritance, so we preliminary speculated that inference CMV resistance is controlled by multiple recessive gene.2. After analysis of F2population phenotype data through the IECM algorithm, we found that CMV resistance-association genes were controlled by two pairs of additive-dominant-epistatic major genes and additive-dominant-epistatic polygenic, moreover, the inherited traits were controlled by the major genes. In our research, Additive effect and dominant effect of the main genes was3.04and0.54and was-3.07and-0.54respectively. In addition, heritability of the main genes and polygenes in F2population were69.04%and0.85%respectively, and genetic variance of the main genes and polygenes in F2population were5.17and0.04respectively, It is obviously found that heritability and genetic variance of the main genes is higher that polygenes, so the inherited traits were controlled by the major genes3. Based on screening the2317SSR primers in24linkage groups,62polymorphic markers were obtained and used to analysis the BC1population. It is showed that the resistant-association traits of Taiyan-8were controlled by Polygenes in one QTL that located in linkage group10by constructing the genetic linkage map of tobacco, of which, DNA marker53735was found closely linked to this resistance-association QTL that genetic distance is0.1cM and contribution rate of the QTL linkage group is13%.