Molecular Marker And Mapping Of Phytophthora Resistant Gene In Cultivar Soybean Yudou 25

Phytophthora root rot is one of the most important diseases on soybean production and it has occurred throughout the world. Application of the resistant cultivars is the most economic and effective way to control the disease. It brings a large challenge for the resistant breeding due to the high degree variability of Phytophthora. So we must discover novel resistance genes to meet the need for resistance breeding.Yudou 25 is an elite soybean cultivar growing Hhuanghuai region now and has a broad resistance spectrum to Phytophthora root rot. The objectives of this study were to analysis resistance genetic to Phytophthora root rot and molecularly tagged and mapped the resistance gene on Yudou25, resistance identification of Phytophthora to Yudou25,Yudou21,Zaoshu18 and F2:3 progenies of the cross Yudou21/Yudou25 and Zaoshu18/Yudou25; genetic analysis with the F2:3 progenies from two cross lines; polymorphism analysis by microsatellite markers and bulked segregation analysis(BSA), and to locate the major resistance gene .The main results are as follows:1. Inoculated parents and F2:3 populations of the cross Yudou21/Yudou25 and to isentify resistance to Phytophthora root rot in glasshouse at seedling stage, the result showed the resistance to Phytophthora root rot on Yudou25 was controlled by a single gene. The gene is temporarily named as RpsYD25.2. Using polymorphic analysis of microsatellite markers and genetic linkage analysis, in F2:3 population deriverd from the cross of Yudou21/Yudou25, 5 SSR marker including sat₂08, satt530, sat₀84, satt125 and sat₂36 on soybean molecular linkage group N were found linked to RpsYD25 with genetic distance of 9.9 cM, 6.3 cM, 7.6 cM, 10.2 cM and 30 cM respectively. The order of the resistant gene and the markers was sat₂08- satt530- RpsYD25- sat₀84- satt125- sat₂36; in F2:3 population of the cross Zaoshu18/Yudou25, 5 SSR marker including satt125, sat₂75, sat₂66, satt660 and GMABAB on MLG N were found linked to RpsYD25 with genetic distance of 7.9 cM, 7.8 cM, 24.7 cM, 38.8cM and 45.1cM respectively. The order of the resistant gene and the markers was satt125- RpsYD25-sat₂75- sat₂66- satt660-GMABAB.3. Because RpsYD25 was mapped on MLG N near to Rps1 locus, the genetic relationship of RpsYD25 and Rps1 was detected by using the selected SSR markers contained into the Rps1k allele sequence. A SSR marker satt1k6 into Rps1k allele was found to be linked to RpsYD25 with a genetic distance of 19.4 cM in F2:3 population from the crosses Yudou21×Yudou25. Therefore, the Phytophthora resistance gene RpsYD25 in cv. Yudou25 could be a novel allele at Rps1 locus, or novel gene.