Wheat Radiation Hybrids For Functional Genomics and Developing High Resolution Physical Maps For Anchoring Sequence Scaffolds.
Monday, November 4, 2013: 9:50 AM
Tampa Convention Center, Room 33, Third Floor
Ajay Kumar1, Vijay Tiwari2, Raed Seetan3, Yi Wang4, Thomas Drader4, Filippo Bassi5, Omar Al-Azzam3, Muhammad J. Iqbal1, Farhad Ghavami1, Mingcheng Luo6, Yong Gu4, Anne Denton3, Gerard Lazo4, Jeff Leonard7, Mohamed Mergoum8 and Shahryar Kianian9, (1)Department of Plant Sciences, North Dakota State University, Fargo, ND (2)Kansas State University, Manhattan, KS (3)Department of Computer Sciences, North Dakota State University, Fargo, ND (4)USDA-ARS, Western Regional Research Center, Albany, CA (5)International Center for the Agricultural Research in the Dry Areas, Rabat,, Morocco (6)Department of Plant Sciences, University of California, Davis, CA (7)Departments of Crop and Soil Science, Oregon State University, Corvallis, OR (8)Plant Sciences, North Dakota State University, Fargo, ND (9)USDA-ARS Cereal Disease Laboratory, St. Paul, MN
Radiation hybrid (RH) mapping, which uses radiation-induced chromosomal breaks rather than genetic recombination to map markers onto chromosomes, is a powerful tool for mapping markers and genes at a much higher and more uniform resolution across the genome, including low recombination regions. In the present study, we developed two RH panels of more than 4,000 lines for wheat D-genome progenitor Aegilops tauschii and reference hexaploid wheat ’Chinese Spring’. Mapping resolution of these RH panels were estimated, using markers of known physical distance, to be less than 140kb. Utilizing a total of 178 lines from Aegilops tauschii RH panel, 610 markers (DArT and SSR) were mapped to the seven D-genome chromosomes, which when compared to the past studies, suggested that RH approach was able to map nearly 10 times more markers than bi-parental genetic populations. These RH maps covered a total of 14,435.1 cR in length with an average distance of 23.7 cR (or 1.7 cM or 8.1Mb) between any two marker loci. The average estimates for Mb/cR was 0.34, while cM/cR it was 0.07, suggesting almost 17 times higher resolution compared to available genetic maps. When RH is used to anchor BAC contigs and sequence scaffolds, we were able to separate markers which co-segregated in genetic maps. Moreover, significantly more sequence scaffolds which could not be anchored to the chromosomes using genetic maps, possibly due to lack of polymorphism, were anchored using RH maps. We have now genotyped ~850 RH lines with a 45K NimbleGen array and the data is being used to construct high-resolution RH-based physical maps that will be used to anchor the BAC based contigs and sequence scaffolds for wheat D-genome assembly. These radiation hybrids are also valuable resources for fine mapping and map based cloning studies of genes present on the D- genome.
