2013 Annual Report
1a.Objectives (from AD-416):
1. Develop winter wheats adapted to the Great Plains with novel starches for use in biofuel production and in food product manufacturing. Improve gluten strength and extractability of such wheats to produce a more economically viable package for producers and end-users.
2. Develop hard white winter wheat germplasm with tolerance to pre-harvest sprouting and with nil levels of grain polyphenol oxidase (PPO).
3. Coordinate the Hard Winter Wheat Regional Nursery Program to facilitate the evaluation, distribution, and exchange of high-yielding, high-quality, disease- and pest-resistant hard winter wheats for Great Plains environments. Develop and disseminate winter wheats with resistance to Ug99 and other cereal rusts.
1b.Approach (from AD-416):
Winter wheats with waxy (amylose-free) starch suitable for cultivation in the Great Plains and the Pacific Northwest will be developed via intermatings with adapted types and recurrent selection. Fermentation assays will be used to determine the most suitable starch composition for conversion of wheat grain and starch to ethanol. Transgenic wheats over-expressing native high-molecular-weight glutenin proteins will be tested as a means of overcoming the technical problem of low gluten extraction from waxy wheats. Hard white wheat germplasm with tolerance to pre-harvest sprouting will be identified by use of controlled environment studies, and molecular markers.
Hard red winter wheat lines capable of serving as donors of genes for resistance to pre-harvest sprouting in white wheats will be identified after diallel matings. Hard white winter and spring wheat germplasm, with nil levels of grain polyphenol oxidase, will be identified after intermatings of non-adapted donor lines, and adapted materials. Field and laboratory studies will be used to evaluate the environmental stability of the trait and identify molecular markers linked to the trait.
This project terminated during FY2013, and was replaced by Project # 5440-21000-031-00D, entitled “Genetic Improvement of Winter Wheat for End-Use Quality and Disease Resistance.” The completed project developed a germplasm base of waxy durum and common winter wheats that were distributed to breeding programs across the globe. The materials also were used in product-development. Starch from waxy wheats was chemically modified by three procedures, and found to have dramatically enhanced viscosity after cooking, relative to normal wheat. This project also investigated the effects of altering wheat glutenin protein profiles via genetic engineering. A team effort by this project and cooperating ARS scientists at Albany, CA and Manhattan, KS identified a transgenic event, B52a-6, capable of providing enhanced dough strength but still at commercially useful levels. Most past experiments resulted either in little effect, or an effect that was too dramatic for practical application. Additional experiments demonstrated B52a-6 can provide enhanced performance in sponge and dough applications, the most commonly used commercial bake procedure. Additional work in this project included investigations on the genetics of key quality attributes essential to the development of the hard white wheat industry in the Great Plains. Evaluation of germplasm maintained at the USDA-ARS National Small Grain Collection in Aberdeen, ID resulted in the identification of accessions from Australia that carry natural mutations that eliminate wheat grain polyphenol oxidase. Wheat carries multiple genes encoding grain polyphenol oxidase, but genetic studies revealed that lines with these newly discovered mutant genes at one specific genetic locus have the lowest activity. These mutants were used to create lines with nil polyphenol oxidase activity, and these lines are now being used in NE, CO and MT wheat breeding programs. In addition, the project cooperated with USDA-ARS scientists at Manhattan, KS to identify a gene, present in the keystone HWWW cultivar Rio Blanco, enhancing tolerance to pre-harvest sprouting. Further investigations assessed the value of this and additional quantitative trait loci contributing to tolerance across multiple genetic backgrounds, with the Rio Blanco derived gene, QPhs.pseru-3AS, again demonstrating significant contributions. Two germplasm lines carrying QPhs.pseru-3AS were entered in the USDA-ARS Northern Regional Performance Nursery in 2012 and tested in the University of Nebraska Organic Wheat trials. The Southern and Northern Regional Performance nurseries, coordinated by this project since 1998, serve as excellent vehicles to characterize all newly developed germplasm, and distribute it to Great Plains breeding programs. In addition, the nurseries serve as sources of information on trends in breeding in the region. A significant accomplishment of the project was the use of these long-term datasets from the USDA-ARS coordinated winter wheat regional nursery program to determine the rate of genetic gain in wheat yields since 1959. Over a 50 year period, genetic potential for grain yield increased at 1% per year.
Progress in the reduction of yield and quality losses due to pre-harvest sprouting. ARS scientists at Lincoln, NE, in cooperation with scientists at the USDA-ARS Small Grains Genotyping Laboratory at Manhattan, KS, developed genetic materials that assisted in the identification of an important gene reducing susceptibility to pre-harvest sprouting in hard white wheats. Another requisite characteristic of hard white wheats, tolerance to preharvest sprouting reduces financial losses to wheat producers during seasons with excess moisture close to harvest. This trait will be especially important under fluctuating precipitation patterns resulting from climate change.
Development and release of wheats with novel end-use properties. ARS scientists at Lincoln, NE developed wheat with altered grain quality properties in-demand by the food processing industry. Developed materials include the cultivar ‘Mattern’ and an extensive array of common and durum wheat breeding lines with waxy (amylose-free) starch. Additionally, ARS scientists identified a gene affecting wheat grain polyphenol oxidase levels. Low levels of polyphenol oxidase are required in newly released hard white wheat cultivars; the previously unidentified gene was discovered in Australian wheats developed in the 1930’s, and maintained by the USDA-ARS National Small Grains Collection in Aberdeen, ID. It effectively eliminates grain polyphenol oxidase in common wheat. Thus, discoloration in fresh and frozen products developed from hard white winter wheats can be avoided, and U.S. markets potentially expanded.
Graybosch, R.A., Seabourn, B.W., Chen, Y.R., Blechl, A.E. 2013. Effects of transgene-encoded high-molecular weight glutenin proteins in wheat flour blends and sponge and dough baking. Cereal Chemistry. 90(02): 164-168.
Hogg, A.C., Gause, K., Hofer, P., Martin, J.M., Graybosch, R.A., Hansen, L.E., Giroux, M. 2013. Creation of a high-amylose durum wheat through mutagenesis of starch synthase II (SSIIa). Journal of Cereal Science. 57:377-383.
Nilthong, S., Graybosch, R.A., Baenziger, S.P. 2012. Inheritance of polyphenol oxidase activity in wheat breeding lines derived from matings of low polyphenol oxidase parents. Euphytica. DOI 10.1007/s10681-012-0777-y.
Nilthong, S., Graybosch, R.A., Baenziger, S.P. 2012. Inheritance of grain polyphenol oxidase (PPO) activity in multiple wheat (Triticum aestivum L.) genetic backgrounds. Theoretical and Applied Genetics. DOI 10.1007/s00122-012-1947-y.
Hunt, H.V., Moots, H.M., Graybosch, R.A., Jones, H., Parker, M., Romanova, O., Jones, M.K., Howe, C.J., Trafford, K. 2012. Waxy-phenotype evolution in the allotetraploid cereal broomcorn millet: Mutations at the GBSSI locus in their functional and phylogenetic context. Molecular Biology and Evolution. DOI: 10.1093/molbev/mss209.
Graybosch, R.A., St Amand, P., Bai, G. 2013. Evaluation of genetic markers for prediction of pre-harvest sprouting tolerance in hard white winter wheats. Plant Breeding. doi:10.1111/pbr.12071.