AFLP Markers for Mapping and Characterization of a New Hessian Fly Resistance Gene

Abstract

Several newly identified genes for resistance to Biotype L of the Hessian fly, Mayetiola destructor (Say), are being combined into a single line of common wheat (Triticum aestivum L. em Thell.) to test whether gene pyramiding increases the durability of resistance in the field. Durum wheat lines (Triticum turgidum L.) served as resistant donors during the construction of five common wheat lines (HF1-HF5). Because lines HF1-HF5 are phenotypically identical with respect to Biotype L resistance, molecular markers are needed to ensure that multiple genes for resistance have been combined into one line. Hessian fly screens of progeny from backcross populations between HF1-HF5 and ‘Cardinal’ suggest that resistance in each line is conferred by a single gene. This test also gave an indication of the relative strength in heterozygotes of the 5 new genes. The gene in line HF4 showed the strongest resistance response followed by the gene in HF5, while the gene in line HF1 was the weakest. Diallel crosses were constructed between pairs of lines to determine that the 5 new genes reside at independent loci. A set of crosses was made between the resistant line HF4 and the susceptible line ‘Ning 7840’ in order to identify and map molecular markers for the resistance gene in HF4. Sixty-four Amplified Fragment Length Polymorphism (AFLP) primer pairs were used for bulk segregant analysis of the HF4/Ning F2 population to identify 1 AFLP marker linked to the HF4 resistance allele and 2 AFLP markers linked to the allele for susceptibility.