Abstract:
Using bulked segregant analysis, five RAPD markers were identified that were
linked in coupling to a gene conferring complete resistance to eastern filbert blight caused
by Anisogramma anomala (Peck) E. Muller in hazelnut (Corylus avellana L.). Two
modified backcross populations were inoculated and scored for resistance to the pathogen
and found to segregate in a 1:1 ratio. In the first population, the five markers were linked
to the resistance gene at distances of 6.7, 0, 2.0, 2.0, and 2.0 cM. Three of these markers
also were linked in coupling in the second population at distances of 6.0, 6.0, and 4.0 cM.
Two of these markers were cloned and sequenced, and primers were designed based on
the sequence information at the termini of the amplified marker fragments. These
primers were used to amplify DNA from both populations and evaluated for their
potential use in selecting for resistance among seedlings. One of these cloned markers
(SC152800) produced the same polymorphism among both populations and was consistent
with the linkage exhibited by the original RAPD marker. These primers were also used
to amplify DNA from a collection of germplasm accessions used in the hazelnut breeding
program. A fragment of similar size was amplified in all of the resistant germplasm
tested, and also in some of the susceptible selections. This marker was shown to have
potential for use in marker-assisted selection for breeding hazelnut cultivars resistant to
eastern filbert blight.
