Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/1999
Publication Date: N/A
Interpretive Summary: The soybean cyst nematode (SCN) is the most destruction pest encountered by US soybean producers. By far the most widely used method of controlling SCN is the use of resistant cultivars. A number of resistance genes need to be combined or Apyramided@ to obtain a highly resistant cultivar. The most important of these genes is the rhg1 resistance gene. The identification of SCN resistant plants would be expedited if plants carrying rhg1 could be selected in an efficient and inexpensive manner. Here we report the development and release of two highly versatile simple sequence repeat (SSR) DNA markers (BARC-Satt309 and BARC-Sat 168) that will allow soybean breeders to identify soybean plants that carry resistance at the rhg1 locus. These markers are already being used by both public and private soybean breeders to select SCN resistant soybean plants.
Technical Abstract: The soybean cyst nematode (SCN) is the economically most significant soybean pest. The principal strategy to reduce or eliminate damage from this pest is the use of resistant cultivars. Identifying resistant segregants in a breeding program is complicated by the oligogenic nature of the resistance and genetic variability in the pathogen. Fortunately, resistance at one SCN resistance locus, rhg1, is accepted as a necessity for the development of resistant cultivars. Thus, the development of SCN resistant genotypes would be expedited if an effective system were available to identify breeding lines carrying resistance alleles at the rhg1 locus. In this study we report two simple sequence repeat (SSR) loci that cosegregate and map 0.4 centiMorgans from rhg1. Allelic variation at the first of these loci, BARC-Satt309, distinguished most, if not all, SCN susceptible genotypes from those carrying resistance derived from the important SCN resistance sources >Peking=, PI 437654, and PI 90763. A second SSR locus, BARC-Sat_168 distinguished the resistance sources PI 88788 and PI 209332 from southern US cultivars such as >Lee=, >Bragg= and >Essex=. Both BARC-Satt309 and BARC-Sat_168 were used to assay lines from SCN susceptible x SCN resistant crosses and proved to be highly effective in identifying lines carrying rhg1 resistance from those that were susceptible.