Mapping Quantative Trait Loci(QTL) Affecting Tolerance To Phyphthora Root Rot In Soybean Using Simple Sequence Repeat (SSR) And Random Amplified Polymorphic DNA (RAPD) Markers

Molelcular breeding is becoming more and more practical technology for plant breeding. The use of markers in plant breeding for indirect selection of important traits can favorably impact breeding efficiency. The present objective is to identify quantitative trait loci (QTLs) on the linkage groups, which are associated with the tolerance to soybean phytophthora root rot (PRR), A RIL population from a cross between Conrad, a soybean cultivar tolerance to PRR disease, and OX760, a breedling lines susceptible to phythora root rot was used in this experiment DNA was extracted from F₆ RIL lines and amplified via polymerase chain reaction using simple sequence repeat (SSR) markers and Random Amplified Polymorphic DNA (RAPD) markers. A total of 39 RAPD markers and 45 SSR markers, which were polymorphic and clear segregated were used for subsequent QTLs analysis.Combining the resistance data resistance from two locations (Woodslee and Weaver) and two years (2000 and 2001).All markers were used to construct a genetic linkage map using Mapmaker/EXP3.0b; putative QTLs were detected using WinQTLCart (V2.0), if log-likelihood (LOD) was set as 2.0, Four markers OPL18-800bp, OPN03-600bp, Satt536 and Satt463, associated wih PRR Tolerance were detected on linkage group MLGD1b+w and linkage group MLGM, were significantly associated with PRR tolerance. They explained 13.34% to 22.31% of the phenotypic variance for the yield loss of caused by PRR disease. Three putative QTLs, namely QPRR-1 (QOPL18-800bp), QPRR-2 (QOPN03-600bp) and QPRR-3 (QSatt536-Satt463) corresponding to these four markers, were identified. Multiple QTL analysis showed that QPRR-1 and QPRR-2 together explained 44.5% of the phenotypic variation for the yield loss based on the two locations (Woodslee and Weaver) and two years (2000 and 2001) data. QPRR-3 explained 15.2% of the phenotypic variation of the yield loss in Woodslee locations for year 2001. QPRR-1 explained 21.55% of the variation in Woodslee location for year 2000, 16.71% of the variation in Wever location for year 2000, and 22.31% of the variation in two locations (Woodslee and Weaver) for two years (2000 and 2001). A few QTLs associated with the tolerance to PRR were detected to exist stably across mutiple environments in this study, which will benefit for the effetive selection of PRR tolerance soybean in breeding program。...