H22, a major resistance gene to the Hessian fly (Mayetiola destructor), is mapped to the distal region of wheat chromosome 1DS.

H22 is a major resistance gene conferring high-level of antibiosis to Hessian fly [Mayetiola destructor (Say)] larvae. It was previously assigned to wheat chromosome 1D through monosomic analysis (Raupp et al. in J Hered 84:142-145, 1993). The objective of this study was to identify molecular markers that can be used for marker-assisted selection for wheat breeding, and to further map this gene toward map-based cloning. Forty-five simple sequence repeat (SSR) and sequence-tagged site (STS) markers specific to chromosome 1D were evaluated for linkage to H22 using a segregating population consisting of 192 F(2:3) families, which were derived from the cross Tugela-Dn1 x KS85WGRC01(H22). The STS Xhor2kv and SSR Xgdm33 are two flanking markers that are tightly linked to H22 at genetic distances of 0.3 and 1.0 cM, respectively. Five other SSR markers including Xgpw7082, Xwmc147, Xcfd15, Xwmc432 and Xwmc336 were also linked to H22 at the distance from 0.8 to 20.8 cM. Analysis of Chinese Spring (CS) deletion lines revealed that all the H22-linked markers are located distal to the breakpoint of del 1DS-5, indicating that the H22 gene is located at the distal 30% region on the short arm of wheat chromosome 1D. Genomic comparison suggested that the H22 gene is located in the same or similar chromosomal region as the leaf rust resistance genes Lr21 and Lr40 on 1DS, and orthologous to the H9 gene cluster of 1AS.