Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/9/2006
Publication Date: 6/15/2006
Citation: Wang, T., Xu, S.S., Harris, M.O., Hu, J., Liu, L., Cai, X. 2006. Genetic characterization and molecular mapping of Hessian fly resistance genes derived from Aegilops tauschii in synthetic wheat. Theoretical and Applied Genetics. 113:611-618. Interpretive Summary: Hessian fly is a serious pest of wheat. Its widespread outbreaks at irregular intervals or sporadic outbreaks in the wheat-producing regions cause extensive local or regional crop losses. In Hessian fly management, breeding for host resistance has been the most successful and widely applied strategy. Recently, two synthetic hexaploid wheat (SHW) lines, SW8 and SW34, were released as germplasm resistant to Hessian fly. Bread wheat is a hexaploid, and these so-called synthetic hexaploid wheats were developed from crosses of the durum wheat cultivar Langdon (a tetraploid) with two accessions of goat-grass (Triticum tauschii), the diploid D-genome donor of common wheat. Previous studies revealed that the resistance genes in the two SHW lines were derived from the T. tauschii parents. To date, 32 resistance genes (designated H1 through H32) have been identified and six of them, including H13, H22, H23, H24, H26, and H32, were derived from T. tauschii. This study was undertaken to determine which resistant genes the two SHW lines carry and to map (or locate) the genes using molecular markers. The study showed that SW8 and SW34 carry resistance genes that are the same as H26 and H13, respectively. H26 and H13 were previously localized to chromosome 4D and 6D by other studies, respectively. However, mapping in the present study assigned the H26 to chromosome 3D rather than 4D, while mapping of the resistance gene in SW34 confirmed the previous assignment of H13 to chromosome 6D. A linkage map showing where these two resistance genes are located has been constructed using molecular markers. The molecular markers linked to the Hessian fly resistance genes revealed in this study could make it easier for plant breeders to incorporate this resistance during the breeding process.
Technical Abstract: Two synthetic hexaploid wheat lines (×Aegilotriticum spp., 2n=6x=42, genomes AABBDD), SW8 and SW34, developed from the crosses of the durum wheat cultivar Langdon (Triticum turgidum L. var. durum, 2n=4x=28, genomes AABB) with two T. tauschii (Coss.) Schmal accessions (2n=2x=14, genome DD), were determined to carry Hessian fly [Mayetiola destructor (Say)] resistance genes derived from the T. tauschii parents. SW8 was resistant to the Hessian fly biotypes Great Plains (GP) and vH13 (virulent to H13). SW34 was resistant to the biotype GP, but susceptible to vH13. Allelism tests indicated resistance genes in SW8 and SW34 were allelic to or the same as H26 and H13, respectively. H26 and H13 were localized to chromosome 4D and 6D in previous studies, respectively. Molecular mapping in the present study, however, assigned the H26 locus to chromosome 3D rather than 4D. On the other hand, mapping of the resistance gene in SW34 verified the previous assignment of the H13 locus to chromosome 6D. Linkage analysis positioned the H26 locus to the chromosomal deletion bin 3DL3-0.81-1.00. A linkage map for each of these two resistance genes was constructed using SSR (simple sequence repeat) and TRAP (Target region amplification polymorphism) markers.