Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 24, 2010
Publication Date: June 1, 2010
Citation: Yu, G.T., S.S. Xu, M.O. Harris, X. Cai, C.E. Williams, Y.-Q. Gu, and M.-C. Luo. 2010. Development of PCR-based markers for marker-assisted selection of H26 and H32 for Hessian fly resistance. p. 328. In: Abstract of Oral and Poster Presentations, 8th International Wheat Conference, June 1 - 4, St. Petersburg, Russia. Technical Abstract: Hessian fly [Mayetiola destructor (Say)] is one of the most destructive insects in common wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum). Growing Hessian fly-resistant cultivars has been the most effective way to minimize the economic losses caused by the pest. So far, a total of 32 Hessian fly-resistance genes have been identified in wheat and its relatives. The Hessian fly-resistance genes H26 and H32, derived from Aegilops tauschii Cosson, are among the most effective resistance genes against Hessian fly populations with high frequencies of virulent genotypes. Both H26 and H32 were previously mapped to the chromosome deletion bin 3DL3-0.81-1.00 with a limited number of molecular markers in a synthetic hexaploid wheat (SHW) F2 population and the ITMI (International Triticeae Mapping Initiative) population, respectively. To facilitate the deployment of these two genes in wheat cultivars, we have developed more molecular markers closely linked to these two genes. In this research, we first developed STS (sequence tagged site) markers from the wheat ESTs mapped to the deletion bin 3DL3-0.81-1.00 for saturation mapping of H26 and H32. Then we exploited the collinearity of the chromosomal region harboring these two genes and corresponding genomic regions of rice (Oryza sativa L.) and Brachypodium distachyon (L.) P. Beauv. to identify additional wheat ESTs residing near the H26 and H32 loci for saturation mapping. A population of 96 F2 individuals, which segregated at the H26 locus, was used for saturation mapping. A total of 26 new STS markers were mapped to the chromosomal region harboring H26. Two of them were mapped to 1.0 cM away from the H26 locus. Further saturation and fine mapping in a large Ae. tauschii F2 population (1,700 individuals) has positioned the H26 locus to a chromosomal interval of 0.54 cM. To develop STS markers closely-linked to H32, the 26 STS markers we mapped to the deletion bin 3DL3-0.81-1.00 were first screened for polymorphisms at the marker loci between the two ITMI parents, W7984 and Opata 85, and then analyzed the polymorphic markers in the ITMI population. To identify additional markers linked to H32, we tested 72 STS primer pairs and 11 SNP primer pairs for polymorphisms between the two parents and mapped the polymorphic markers. Eleven of the STS markers linked to H26 and three new STS markers were mapped to the H32 region in the ITMI population. Two of the STS markers were found to flank the H32 locus with a genetic distance of 0.5 cM on both sides of H32 and another STS marker co-segregated with H32. We validated three STS markers tightly linked to H26 and H32 in 12 bread wheat cultivars and one advanced breeding line and successfully utilized the markers to assist the deployment of the two genes into adapted bread wheat germplasm.