Reassigning Hessian fly resistance genes H7 and H8 to chromosomes 6A and 2B of the wheat cultivar 'Seneca' using genotyping-by-sequencing

Hessian fly (HF, Mayetiola destructor Say), is a destructive insect pest in most wheat (Triticum aestivum L.) growing areas worldwide. Growing resistant cultivars can effectively reduce HF damage. The wheat cultivar 'Seneca' was reported to carry resistance genes H7 on chromosome 5D and H8 with unknown location. To further validate the resistance gene locations in Seneca, a recombinant inbred line (RIL) population from Bobwhite x Seneca was genotyped using 3,330 single nucleotide polymorphism (SNP) markers generated from genotyping-by-sequencing (GBS) and phenotyped for HF resistance in the greenhouse experiments. Phenotypic analyses showed at least two genes conditioning HF resistance in Seneca, but none of them was mapped on chromosome 5D, as previously reported. Instead, one major gene, designated as H7, was mapped to chromosome 6A and explained 60.7-78.3% of the phenotypic variation. The other gene with a minor effect, designated as H8, was found on chromosome 2B and explained 3.2-4.7% of the phenotypic variation. Based on the physical locations of flanking markers for H7 in the Chinese Spring reference genome, H7 was physically located in a 6-Mb interval on 6AL. This study reassigned the major gene H7 to chromosome 6A and the minor gene H8 to 2B in Seneca using a high-density SNP map. Seventeen GBS SNPs mapped in the H7 region were converted into Kompetitive allele specific polymerase chain reaction (KASP) markers for selecting this gene in breeding.