Selection of DNA markers closely linked to the resistance gene rym7t against Barley yellow mosaic disease

Abstract

This study was conducted to select a DNA marker linked to the new recessive resistance gene rym7t, which is derived from 'Tokushima mochihadaka' and confers resistance to Barley yellow mosaic virus (BaYMV) strains I, II and III. A genetic linkage map neighboring rym7t was constructed using doubled haploid lines derived from a cross between the resistant parent 'DH21-73,' which includes rym7t, and susceptible parent 'Haruna Nijo'. Two SSR markers, Bmac0031 and Bamc0167 were selected, adjacent to each side of the rym7t locus. The genotype of the two SSR markers corresponded well to the phenotype of BaYMV resistance. The field test of Barley yellow mosaic disease (virus strain I) resistance of F2 individuals derived from a cross between the susceptible parent 'New Golden' and resistant parent 'DH42-84,' which includes rym7t, showed that the correspondence rates between phenotypes of BaYMV resistance and genotypes with Bmac0031 and Bamc0167 were 98.6% and 98.8%, respectively. In the case of correspondence between the two markers' genotypes, they corresponded exactly with the phenotype of BaYMV resistance of F2 individuals. The two SSR markers were co-dominant, so both could clearly identify susceptible plants with heterozygous rym7t. The two SSR markers could be useful for marker-assisted selection of resistant lines including rym7t.