MOLECULAR MARKERS FOR THE SCAB RESISTANCE (V-F) REGION IN APPLE

Bulked segregant analysis was used to identify RAPD markers that displ ay tight linkage to the V-f gene in apple (Malus sp.) that confers res istance to five races of apple scab [Venturia inaequalis (Cke.) Wint.] . We identified several new RAPD markers linked to V-f. The most tight ly linked marker in the test population, S5(2500), was cloned and sequ enced. A linkage map of the V-f region was developed using these marke rs, RAPD markers previously described by other laboratories, and the i sozyme 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 theoreti cal 'escape' value (discarding a resistant plant) of 3% and an error r ate (selection of a susceptible plant) of 0.02%.