QTL Mapping Of Verticillium Wilt Resistance And Diversity Of Species In Tomato

Object:Verticillium wilt is a worldwide destructive tomato disease, SSR molecular markers are used for constructing genetic linkage map and the quality trait of tomato resistance to Verticillium wilt located, set up Molecular Marker-assisted Selection (MAS), which will comprehensively promote the process of resistance breeding in tomato.The genetic diversity of germplasm resources is the basis for breeding. Using SSR marker analyzed genetic diversity of tomato varieties,which were bred by Xinjiang Province or introduced from Ameican,the goal of this is providing a theoretical basis for breeding new varieties.Methods:Based on 184 F2:3 family lines from cross between SH303-M (resistant toVerticillum)×SH303-F (unresistant to Verticillum), a combined SSR genetic map of tomato has been constructed and an initial QTL mapping of tomato has been performed.Using SSR marker for genetic diversity to 48 tomato varieties, by NTSYS-pc Version 2.0 software to calculate genetic similarity cofficients and complete genetic clustering.Results and Conclusions: 1. The statistic analysis of resistant traits of F2:3 family lines showed that the resistance were controlled by a pair of genes, result of X2 test accorded with 3:1.2. The 500 pairs of SSR primers were used to screen the polymorphism of parents, polymorphism primers were obtained to analyse the F2 population and amolecular genetic linkage Map covering 217.2cM of the tomato genome and including 6 linkage groups with an average distance of 5.57 cM was constructed.3. There resistant QTLs were detected by composite interval mapping(CIM) method, named Qve1, Qve3, Qve5 and they explained 16.7%,28.9% and 31.6% of the phenotpic variation, respectively. Qvel coverage region between 16.35 cM and 24.66 cM, the distance of left and right primers SSR1, SSR226 is 1 cM and 2.24 cM, Qve3 coverage region between 6 cM and 16 cM, the distance of left and right primers TOM144, TC167949 is 9 cM and 1.33 cM, Qve5 coverage region between 17 cM and 29 cM, the distance of left and right primers SSR19, TC155130 is 17 cM and 7.34 cM.4.The genetic similarity coefficient of paired varieties ranged from 0.575 to 0.986 with average 0.809, and the genetic similarity of 90.1% tested materials ranged from 0.735 to 0.935.the similarity coefficient of 0.900 or more accounted for 10.45%, the similarity coefficient max reached 0.986.5.When genetic similarity at 0.80, the results of UPGMA indicated that the 48 tomato varieties could be clustered into six groups.The first category included 31 species, the second, three, five, six category included only one species, The four category included 31 species. Based on the pedigree analysis, it was concluded that the tomato varieties in Xinjiang Province had closer genetic relationship with each other and the genetic diversity was not enough at present.