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Title: Quantitative trait loci associated with the tocochromanol (vitamin E) pathway in barley

Author
item GRAEBNER, RYAN - Oregon State University
item Wise, Mitchell
item CUESTA-MARCOS, ALFONSO - Oregon State University
item GENIZA, MATTHEW - Oregon State University
item BLAKE, TOM - Montana State University
item Blake, Victoria
item BUTLER, JOSHUA - Anheuser-Busch
item Chao, Shiaoman
item HOLE, DAVID - Utah State University
item HORSLEY, RICH - North Dakota State University
item JAISWAL, PANKAJ - Oregon State University
item OBERT, DON - Limagrain Cereal Seeds
item SMITH, KEVIN - University Of Minnesota
item ULLRICH, STEPHEN - Washington State University
item HAYES, PATRICK - Oregon State University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 7/24/2015
Citation: Graebner, R.C., Wise, M.L., Cuesta-Marcos, A., Geniza, M., Blake, T., Blake, V.C., Butler, J., Chao, S., Hole, D.J., Horsley, R., Jaiswal, P., Obert, D., Smith, K.P., Ullrich, S., Hayes, P.M. 2015. Quantitative trait loci associated with the tocochromanol (vitamin E) pathway in barley. PLoS One. 10(7): e0133767. DOI:10.1371/journal.pone.0133767.

Interpretive Summary: Interest in food barley as a source of healthful nutrition is increasing. Barley is now recognized as a significant source of soluble fiber (beta-glucans) with their associated cholesterol lowering properties. Barley is also a rich source of vitamin E and, unlike most sources, also produces each of the other seven compounds in the tocochromanol (vitamin E) family. These metabolites are produced in varying degrees in the barley crop and appear to be largely under genetic control. Thus a better understanding of the locations of the genes controlling their expression within the barley genome is essential for breeding cultivars with superior vitamin E content. This paper identifies the genetic loci of several genes specifically involved in tocochromanol biosynthesis and other regions of DNA which likely control their production (quantitative trait loci (QTL)). Using the technique of genome wide associations study (GWAS) the authors identify three chromosomes (1H, 6H and 7H) as the location for several QTLs associated with tocochromanol production. In fact, two genes coding for enzymes involved in tocochromanol biosynthesis were identified on chromosomes 6H and 7H. This is in agreement with a previously published study on barley tocochromanol production that employed a bi-parental genetic mapping approach. The impact of this work will be to facilitate breeding of barley cultivars with more desirable vitamin E composition; it also further substantiates the utility of GWAS as a tool for QTL mapping in cereal crops.

Technical Abstract: In this study, the Genome-Wide Association Studies approach was used to detect Quantitative Trait Loci associated with tocochromanol concentrations using a panel of 1,466 barley accessions. All major tocochromanol types- alpha-, beta-, delta-, gamma-tocopherol and tocotrienol- were assayed. We found 13 single nucleotide polymorphisms associated with the concentration of one or more of these tocochromanol forms in barley, seven of which were within 2.5 cM of sequences homologous to cloned genes associated with tocochromanol production in barley and/or other plants. The discovery of these loci could aid future breeding efforts to develop barley varieties with higher tocochromanol concentrations. At current recommended daily consumption amounts, barley would not be an effective sole source of vitamin E. However, it could be an important contributor in the context of whole grains in a balanced diet.