Molecular Markers Useful for Detecting Resistance to Brown Stem Rot in Soybean

Abstract

Brown stem rot (BSR) causes vascular and foliar damage in soybean [Glycine max (L.) Merr.]. Identification of plants resistant to BSR by inoculation with Phialophora gregata (Allington & W.W. Chamberlain) W. Gams is laborious and unreliable because of low heritability. Molecular markers linked to the resistance gene could be used to screen for resistant individuals and hasten the development of BSR resistant genotypes. The objective of this study was to develop molecular markers for efficient identification of BSR resistant plants in a breeding program. Seventeen resistant and 29 susceptible cultivars and plant introductions as well as recombinant inbred lines derived from a cross between BSR 101 and PI 437.654 were assayed by PCR‐based markers derived from RFLPs K375I‐1 and RGA2V‐1, Satt244, or developed from bacterial artificial chromosome (BAC) sequences. The DNA markers that were developed tag the BSR locus and are informative in a diverse range of soybean germplasm. Markers detected different banding patterns between resistant and susceptible genotypes. The PCR‐based markers will most likely be useful in screening for BSR resistance and allow soybean breeders to transfer rapidly resistance derived from Rbs3 to improved cultivars or soybean lines. The markers are relatively easy‐to‐use, inexpensive, and highly informative. Soybean breeding efforts can now be designed to incorporate the use of marker information when parental genotypes possess contrasting banding patterns.