IDENTIFICATION AND MAPPING OF MARKERS FOR RESISTANCE TO APPLE SCAB FROM ‘ANTONOVKA’ AND ‘HANSEN’S BACCATA #2’

Bulked segregant analysis identified several RAPD markers that display close linkage to the genes identified as V_a (from ‘Antonovka’ PI 172633) and V_b (from ‘Hansen’s baccata #2’) that confer resistance to apple scab.
B398₄₈₀ was the closest marker segregating with the resistance response from descendants of ‘Antonovka’ PI 172633 and UBC220₇₀₀ was the closest marker for resistance from ‘Hansen’s baccata #2’. V_a and V_b were found to share flanking markers with each other and with the V_f resistance gene from Malus floribunda 821 and map to the same region as V_f on linkage group 8 of ‘Rome Beauty’ x ’White Angel’. Our study emphasizes the importance of determining the clone to be used in breeding and the need for further allelism tests involving ‘Antonovka’, ‘Hansen’s baccata #2’, ‘Hansen’s baccata jackii’, and other lesser known sources of resistance.
These studies are needed to determine whether resistance from ‘Antonovka’ and ‘M. baccata #2’ is distinct from that of V_f and whether they can be used in breeding for more durable resistance.