Bc-1 and bc-u--two loci controlling bean common mosaic virus resistance in common bean are linked
1999
Strausbaugh, C.A. | Myers, J.R. | Forster, R.L. | McClean, P.E.
Resistance to bean common mosaic virus (BCMV) strain NY15 (Zaumeyer) and bean common mosaic necrosis virus (BCMNV) strain NL-3 (Drijfhout) was assessed in 98 F(5:6) recombinant inbred lines (RILs) derived from across between pinto bean (Phaseolus vulgaris L.) cultivars 'Olathe' and 'Sierra'. 'Olathe' has bc-u and bc-1(2) whereas 'Sierra' has no known resistance genes. The differentiation of resistant and susceptible lines was based on visual symptoms, virus titer, and top dry weight. Forty-seven RILs were moderately resistant to NL-3, while 51 RILs were susceptible. This segregation fits a 1 susceptible:1 resistant ratio characteristic of a single gene. Sixty-nine RILs were susceptible to NY15, while 29 RILs were resistant, which fits a 3 susceptible:1 resistant ratio characteristic of a two-gene model. Moderate resistance to NL-3 was conferred by bc-1(2) with or without bc-u present. Bulked segregant and two point linkage analysis identified randomly amplified polymorphic DNA (RAPD) markers linked in coupling to the Bc-1 and Bc-u alleles. The OH14(1100) RAPD marker was 4.5 cM from the Bc-1 locus. The OC16(1000) RAPD marker was linked at a distance of 10.9 cM from the Bc-u locus. Multipoint analysis, using segregation data for bc-1(2), bc-u, and the two markers, estimated the distance between the Bc-1 and Bc-u loci as 22.8 cM.
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