Date of this Version
J. AMER. SOC. HORT. SCI. 121(6):1035–1039. 1996.
Bean golden mosaic virus (BGMV) is a devastating disease of common bean (Phaseolus vulgaris L.) in tropical America. The disease is effectively controlled by combinations of genetic resistances. The most widely deployed source of resistance to BGMV is a recessive gene (bgm-1) derived from the dry bean landrace cultivar Garrapato (Mexico) that conditions a nonmosaic partial resistance response to the pathogen. To expedite introgression of partial resistance into snap bean for southern Florida and other susceptible dry bean market classes for the Caribbean and Central American regions, a RAPD marker tightly linked to bgm-1 has been identified. Two contrasting DNA bulks, one consisting of five BGMV-resistant and the other five susceptible F6 recombinant inbred lines, were used to screen for polymorphic fragments amplified by 300 decamer primers in the polymerase chain reaction. RAPDs generated between the bulks were analyzed across F2 populations segregating for the marker and the gene. One codominant RAPD marker (R2570/530) tightly linked to the recessive resistance gene bgm-1 was found. The 530-base pair (bp) fragment was linked in repulsion with bgm- 1 and the other 570-bp fragment was linked in coupling. No recombinants between R2570/530 and bgm-1 were observed among 91 F2 progeny from one dry bean population, and there were two recombinants (4.2 cM) observed among 48 F2 progeny combined across four snap bean populations. Assays of R2570/530 across susceptible germplasm and lines likely to have the ‘Garrapato’-derived partial resistance to BGMV have revealed that the codominant marker is gene-pool nonspecific and maintains its original linkage orientation with the recessive bgm-1 gene through numerous meioses. The codominant marker is useful for rapidly introgressing partial resistance to BGMV into susceptible germplasm.