Molecular mapping of a new gene for resistance to frogeye leaf spot of soya bean in 'Peking'

Amplified fragment length polymorphism (AFLP) and microsatellite (simple se quence repeat, SSR) techniques were used to map the Rcs(Peking) gene, which is resistant to most isolates of Cercospora sojina in the soya bran cultiv ar 'Peking'. The mapping was conducted using a defined F-2 population deriv ed from the cross of 'Peking' (resistant) x 'Lee' (susceptible). Of 64 EcoR I and MseI primer combinations, 30 produced polymorphisms between the two p arents. The F-2 population, consisting of 116 individuals, was screened wit h the 30 AFLP primer pairs and three mapped SSR markers to detect markers p ossibly linked to Rcs(Peking). One AFLP marker amplified by primer pair E-A AC/M-CTA and one SSR marker Satt244 were identified to be linked to Rcs(Pek ing). The gene was located within a 2.1-cM interval between markers AACCTA1 78 and Satt244, 1.1 cM from Satt244 and 1.0 cM from AACCTA178. Since the SS R markers Satt244 and Satt431 have been mapped to molecular linkage group ( LC) J of soya bean, the Rcs(Peking) resistance gene was putatively located on the LG J. This will provide soya bean breeders an opportunity to use the se markers For marker-assisted selection for frogeye leaf spot resistance i n soya bean.