ARS | Publication request: Saturation and comparative mapping of genomic region harboring Hessian fly resistance gene H26 in wheat

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2009
Publication Date: March 26, 2009
Citation: Yu, G., Cai, X., Harris, M., Gu, Y.Q., Luo, M., Xu, S.S. 2009. Saturation and comparative mapping of genomic region harboring Hessian fly resistance gene H26 in wheat. Theoretical and Applied Genetics. 118(8):1589-1599.

Interpretive Summary: Hessian fly resistance gene H26 is one of the most effective resistance genes against many types of Hessian fly. Using a limited number of molecular markers, a previously study mapped H26 to the long arm of chromosome 3D in wheat. However, the molecular markers that are currently available are not tightly linked to H26, thus they are not efficient for use in breeding and cloning. The objectives of this study were to saturate the chromosomal region harboring H26 gene with newly-developed molecular markers. A population of 96 individuals segregating for H26 gene was used for saturation mapping gin this study. The DNA sequence information in the chromosomal region harboring H26 in wheat and its collinear region in model species (rice and false brome grass) were used to develop new molecular markers. To date, 26 newly-developed molecular markers have been mapped to the chromosomal region spanning the H26 locus. Two of them are tightly linked to the gene. The newly developed molecular markers closely lined to H26 will be useful for map-based cloning of H26 and marker-assisted selection of this gene in wheat breeding. They will also enhance understanding of this chromosomal region, which contains several Hessian fly resistance genes.

Technical Abstract: Hessian fly [Mayetiola destructor (Say)] resistance gene H26, derived from Aegilops tauschii Coss., is one of the most effective R genes against many biotypes of Hessian fly. Using a limited number of PCR-based molecular markers, a previous study mapped H26 to the wheat (Triticum aestivum L.) chromosomal deletion bin 3DL3-0.81 – 1.00. The objectives of this study were to saturate the chromosomal region harboring H26 with newly-developed PCR-based markers and to investigate the collinearity of this wheat chromosomal region with rice and Brachypodium distachyon genome. A population of 96 F2 individuals segregating at the H26 gene locus was used for saturation mapping in this study. All wheat EST assigned to the deletion bin 3DL3-0.81-1.00 were used to design STS (sequence tagged site) primers. The wheat ESTs mapped near H26 were further used to BLAST rice (Oryza sativa L.) and Brachypodium distachyon genomic sequences for comparative mapping. To date, 26 newly-developed STS markers have been mapped to the chromosomal region spanning the H26 locus. Two of them were mapped 1 cM away from the H26 locus. Comparative analysis identified genomic regions on rice chromosome1 and Brachypodium Super contig 13, which are collinear with the genomic regions spanning the H26 locus within the distal region of 3DL. The newly developed STS markers closely linked to H26 will be useful fro map-based cloning of H26 and marker-assisted selection of this gene in wheat breeding. They will also enhance understanding of this chromosomal region, which contains several Hessian fly resistance genes.