Inheritance Analysis And Initial Gene Mapping Of Complete Resistance To Phytophthora Sojae In Soybean

Phytophthora root rot（PRR）,caused by the soil-borne Oomycete pathogen Phytophthora sojae Kaufmann&Gerdemann（P.sojae）,is a considerable threat to the world’s soybean production.PRR has been reported in most soybean-growing regions throughout the world and caused consistent yield losses of 0.68×106-1.55×106 tonnes from 1996 to 2010 in the United States.The pathogen could infect soybean plant at any growth period.We have taken cultivation and management measures to control the disease to reduce economic loss.Under the pressure of P.sojae races evolvement,the most effective method to reduce damage would be breeding resistant cultivars.Screening resistance sources and discover new resistant genes is the foundation and key to resistant breeding.Soybean cultivar Nannong 508 has been identified as an effective source resistant to PhytoPhthora root rot of soybean.The objectives of this study were to identify and initial map the PhytoPhthora resistance gene in Nannong 508 with bulked segregant analysis in order to facilitate its utilization and marker-assisted breeding.Nannong 508 was crossed with susceptible cultivar 06-070583 to develop mapping populations.The ratio of resistant,seragation and susceptible families in the F2:3 lines was 1:2:1,these results indicated the resistance to Phytophthora sojae in Nannong 508 was controlled by a dominant single gene.The resistance gene was temporarily designated RpsNn508.Nannong508 and 06-070583 were crossed and the F2 seperation population was obtained.300 pairs of SSR primer were sereened and 72 SSR markers were found to have the polymorphism between two Parents.The rate of polymorphism of SSR markers was 24%.The order of four co-dominant microsatellite markers linked to RpsNn508 was established as:Satt159、Sat₁86、satt631 and sattt152.Based on linkage analysis of SSR markers,RpsNn508 was located on soybean molecular linkage group（MLG）N between SSR markers Satt159 and Sat₁86 with genetic distances 6.4 cM and 3.7 cM,respectively.RpsNn508 maybe a new resistance gene or an allele of known resistance genes.