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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVEMENT OF HARD RED SPRING AND DURUM WHEAT FOR DISEASE RESISTANCE AND QUALITY USING GENETICS AND GENOMICS

Location: Cereal Crops Research

Title: Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landrace and cultivars

Authors
item Cavanagh, Colin -
item Chao, Shiaoman
item Wang, Shichen -
item Huang, Bevan -
item Stephan, Stuart -
item Kiani, Seifollah -
item Forrest, Kerrie -
item Saintenac, Cyrille -
item Brown-Guedira, Gina
item Akhunova, Alina -
item See, Deven
item Bai, Guihua
item Pumphrey, Michael
item Tomar, Luxmi -
item Wong, Debbie -
item Kong, Stephan -
item Reynolds, Matthew -
item Lopez Da Silva, Marta -
item Bockelman, Harold
item Talbert, Luther -
item Anderson, James -
item Dreisigacker, Susanne -
item Baenziger, Stephen -
item Carter, Arron -
item Korzun, Viktor -
item Morrell, Peter -
item Dubcovsky, Jorge -
item Morell, Matthew -
item Sorrells, Mark -
item Hayden, Matthew -
item Akhunov, Eduard -

Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 25, 2013
Publication Date: May 14, 2013
Repository URL: http://handle.nal.usda.gov/10113/57900
Citation: Cavanagh, C., Chao, S., Wang, S., Huang, B.E., Stephan, S., Kiani, S., Forrest, K., Saintenac, C., Brown Guedira, G.L., Akhunova, A., See, D.R., Bai, G., Pumphrey, M.O., Tomar, L., Wong, D., Kong, S., Reynolds, M., Lopez Da Silva, M., Bockelman, H.E., Talbert, L., Anderson, J.A., Dreisigacker, S., Baenziger, S., Carter, A., Korzun, V., Morrell, P.L., Dubcovsky, J., Morell, M., Sorrells, M., Hayden, M., Akhunov, E. 2013. Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landrace and cultivars. Proceedings of the National Academy of Sciences. 110:8057-8062.

Interpretive Summary: Domesticated crops have experienced strong human-driven selection aimed at the development of improved varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated DNA markers based on single nucleotide differences, known as single nucleotide polymorphisms (SNPs), in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. The genetic locations of 7500 of those SNPs on 21 wheat chromosomes were determined and were the basis for this study. The results from genetic diversity analyses showed that wheat improvement has mainly relied on preexisting variation in landraces, and the transition from landraces to cultivars has had little effect on diversity. The analyses further revealed that genetic variation present in cultivars was mainly explained by the geographic origin of breeding pools, and that chromosomal regions targeted by selection for wheat improvement have changed over time, potentially reflecting breeding efforts aimed at developing higher yielding varieties adapted to new or changing local conditions. The limited usage of exotic germplasm for wheat improvement as found in this study provides an important take home message in that breeders can broaden the genetic diversity by integrating landraces and wild relatives in their efforts on wheat improvement.

Technical Abstract: Domesticated crops have experienced strong human-driven selection aimed at the development of improved varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated DNA markers based on single nucleotide differences, known as single nucleotide polymorphisms (SNPs), in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. The genetic locations of 7500 of those SNPs on 21 wheat chromosomes were determined and were the basis for this study. The results from genetic diversity analyses showed that wheat improvement has mainly relied on preexisting variation in landraces, and the transition from landraces to cultivars has had little effect on diversity. The analyses further revealed that genetic variation present in cultivars was mainly explained by the geographic origin of breeding pools, and that chromosomal regions targeted by selection for wheat improvement have changed over time, potentially reflecting breeding efforts aimed at developing higher yielding varieties adapted to new or changing local conditions. The limited usage of exotic germplasm for wheat improvement as found in this study provides an important take home message in that breeders can broaden the genetic diversity by integrating landraces and wild relatives in their efforts on wheat improvement.

Last Modified: 4/18/2014
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