Construction Of Medicago Truncatula Genetic Map By SSR And QTL Location Of Agronomic Traits

As a model plant, M. truncatula provided an important source of information for Soybean and Alfalfa. It had genetic similarity and gene homo logy with soybeans, alfalfa and other crops. It had a significance in Legume crops and forage grass breeding, and the results of many studies of M. truncatula could be used in legumes. In this study, by selecting425pairs of SSR markers and developing part of the SSR markers to construct genetic maps of M. truncatula. Used stretch length, branch number, leaf length, leaf width and other agronomic traits to QTL location. The main results were as follows:1. Using the known M. truncatula EST database to develop the new EST-SSRs markers and analyze the distribution of EST-SSRs. With the285285EST sequences published on NCBI,6688SSR sequences were detected by the software SSRLocatorI, which distributed in6512parts of EST, accounting for2.28%of the EST database. Using SSRLocatorl design100pairs of EST-SSRs primer randomly,29primer EST-SSRs were detected, which had polymorphism in the RIL-8groups. The polymorphic rate was29%.2. In this paper,425pairs of SSR primers were selected, which contained100pairs of EST-SSR primer,133pairs of Mt Series SSR primers and192pairs MtB Series SSR primers. The129marker genetic mapping was built by jionmap3.0with the condition of201pairs of polymorphic primers and the results of gelelectrophoresis PCR. This map contains16linkage groups. Compared with the entire genome length, M. truncatula only covers914cM, the average distance between markers was7.1cM. Finally8linkage groups were integrated. The results show that:42marker loci distributed in8linkage groups.4segregation distortion hotspots distributed in LG3, LG5and LG7.3. Stretch length, branch number, leaf length and leaf width were analyzed by QTL, stretch length and branch number had no corresponding sites, but leaf length and leaf width had5and6QTL sites respectively. The QTL which controlled leaf length distribute in LGlb, LG3, LG6a and LG7c4linkage groups, There were two QTL sites in LG1b, the contribution rate were30.7%and34.9%, LOD values were5.05and6.83, it was the main effect QTL. The5QTLs which controlled leaf width distribute in LGlb,LG2b,LG6a,LG6c,LG7c, and the contribution rate in LGlb was the highest. The LOD in LG6a was4.08.