Inheritance and genetic mapping of resistance to Asian soybean rust in cultivar TMG 803

This study analyzed the inheritance and identified microsatellite markers linked to the resistance gene to Phakopsora pachyrhizi in soybean cultivar TMG 803. Hybridization between the cultivars TMG 803 and BRS Valiosa RR was performed to obtain F-1 progenies and the F-2 population. The response of the parents 'TMG 803' and 'BRS Valiosa RR' to P. pachyrhizi was, respectively, resistant and susceptible, and among the 116 F-2 plants, 93 were resistant and 23 susceptible, under natural infection and field conditions. It was found that the resistance of cultivar TMG 803 is controlled by one gene with complete dominance, mapped as resistance locus Rpp4 of linkage group G. Of the 16 tested, one microsatellite marker, sc21_3420, was completely linked to the resistance gene (distance 0.0cM) and the favorable allelic form was present in cultivar TMG 803, which may therefore be useful in assisted selection in segregating populations.