GENETIC-LINKAGE BETWEEN MEX2, A SPECIFIC RESISTANCE GENE TO ANTHRACNOSE, AND ANP, A GENE INVOLVED IN POD ANTHOCYANIN ACCUMULATION IN BEAN

Breeding tests in bean (Phaseolus vulgaris) with Mex2, a single dominant resistance gene to bean anthracnose, suggested a linkage between this gene and pod anthocyanin accumulation. The cross between an inbred, purple-pod, anthracnose-resistant cultivar with Mex2 (AFN) and an inbred, green-pod, susceptible cultivar (La Victoire) was performed to study the segregation of the two characters and to recover green pod progeny resistant to Mex2, because purple pods are commercially unacceptable. Pod anthocyanin accumulation proved, at least in this cross, to be under the control of a single, dominant Mendelian gene, which has been designated Anp (anthocyanins in the pod). Among 548 plants of F2 progenies, 13 recombinant phenotypes were identified. The genetic distance between Mex2 and Anp was estimated by maximum likelihood analysis to be 2.3 +/- 1.3 cM (95% CI).