Inheritance Of Reistance To Verticillium Wilt And Their Molecular Tagging In Upland Cotton

Verticillium wilt is a worldwide destructive cotton disease. And this disease has been recognized as a serious threat to cotton production. Recently, more and more cotton fields in China have been severely damaged by the disease. It has been testified that breeding for highly tolerant or resistant varieties to Verticillium wilt is the most effective and economical disease control method. However, it is difficult to breed such cultivars because some related questions such as lack of resistant resources, weakness of basic research, and many factors connecting with the disease development. Therefore, if the makers closely linked to the resistant genes of Verticillium wilt are developed to be utilized in MAS breeding, it would be easy and fast to develop the resistant cultivars so as to meet the urgent needs in cotton breeding.Three cultivars or line in Upland cotton were used in this research. Both Nannongzao and Chang 96 are two resistant varieties or lines to Verticillium wilt, and Junmian 1 susceptible one. Both (Nannongzao Junmian 1) and (Chang 96 Junmian 1)F2 and F2:3 family lines were produced in our inheritance and QTL tagging.The major gene plus polygene mixed genetic model was used to analyze the inheritance of resistant trait by using P1,P2, F1 and F2. In the cross (Nannongzao Junmian 1), the best fitness genetic model is E-1, which is two major genes plus polygene mixed genetic model. While in the cross (Chang 96 Junmian 1), there is one major gene for resistant trait. The best fitness genetic model is C-0. The results of analysis are almost consistent with that of QTLs.Five hundreds and one pairs of SSR primers were used to detect if there exited polymorphism between Nannongzao and Junmian 1. It resulted in 51 polymorphic loci amplified by 48 pairs of SSR primers between them. These primers were further used to screen individually the (Nannongzao Junmian 1) F2. Linkage test with the MAPMARKER program resulted in the establishment of nine linkage groups with 24loci, and other 23 loci were independently inherited. Six linkage groups covered a total genetic distance of 188.5 cM (centiMorgan) and localized on the Chr. 5, 10, 15, 17 and 18, respectively. Other three linkage groups covered a total genetic distance of 69.8 cM. Two QTLs controlling susceptible trait were detected and localized on the Chr. 15 and Group LG03. On the Chr. 15, between makers S1693480 and S1666135, one QTL was identified with 13.3% phenotype variance explained in F2- On the Group LG03, between makers S72180 and S32150, another QTL was detected with 30.7% phenotype variance explained in F2.Sixty-two polymorphic loci were detected amplified with 51 pairs of SSR primers between Chang 96 and Junmian 1. Linkage analysis with the MAPMARKER program resulted in the establishment of 10 linkage groups. Twenty-one markers were mapped on eight linkage groups covered a total genetic distance of 222.1 cM and localized on the Chr.5, Chr.9, Chr.10, Chr.12, Chr.17 and Chr.20. Other nine markers were mapped on two linkage groups covered a total genetic distance of 143.1 cM. The ten linkage groups covered a total genetic distance of 365.2 cM. One QTL controlling susceptible trait was identified with 13.8% phenotype variance. It was located between makers S245140 and S666150 on the Chr. 17.By using aneuploid tests, the QTLs for resistant trait were localized on corresponding chromosomes.