Epistasis and Preliminary Fine Mapping of Quantitative Trait Loci for Common Bunt Resistance

Common bunt of wheat caused by Tilletia tritici (Bjerk.) G. Wint. in Rabenh. and T. laevis Kuhn in Rabenh. reduces grain yield and quality.  The objectives of this research were to initiate fine mapping and study the epistatic interactions between quantitative trait loci (QTL) for common bunt resistance. A population of doubled haploid lines from the cross Carberry/AC Cadillac was characterized for common bunt incidence in three years of field nursery testing and was genotyped with simple sequence repeat, DArT®, and single nucleotide polymorphism markers.  A number of loci were identified that expressed bunt resistance, with loci on chromosomes 1B and 6D being the most consistent and having the largest effect. Significant epistatic interactions were identified for percent bunt incidence between chromosome 1B and 4B loci, and between 1B and 6D loci. Candidate markers were identified that will be useful in further fine mapping. New understanding of QTL*QTL interactions will assist in developing effective marker-assisted breeding strategies for common bunt resistance.