Molecular markers for the scab resistance (Vf) region in apple

Bulked segregant analysis was used to identify RAPD markers that display tight linkage to the V-f gene in apple (Malus sp.) that confers resistance to five races of apple scab [Venturia inaequalis (Cke.) Wint.]. We identified several new RAPD markers linked to V-f. The most tightly linked marker in the test population, S5(2500), was cloned and sequenced. A linkage map of the V-f region was developed using these markers, RAPD markers previously described by other laboratories, and the isozyme locus Pgm-1, An assay was developed for V-f by multiplexing the two markers closely flanking the V-f locus. This assay has a theoretical 'escape' value (discarding a resistant plant) of 3% and an error rate (selection of a susceptible plant) of 0.02%.