Location: Wheat, Sorghum and Forage Research2009 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.
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.
3. Progress Report
Waxy wheats have starch properties that differ from normal wheat, with lower cooking properties and the ability to enhance shelf-life of baked goods. Development of adapted waxy wheats could expand the demand for Great Plains wheats. The hard winter waxy wheat NX04Y2107 was entered in the 2008 and 2009 Nebraska statewide variety trials. In two Nebraska counties in 2008, NX04Y2107 was the top yielding wheat, out-performing even the most recent normal wheat cultivars and advanced breeding lines. Early returns on the 2009 harvest have demonstrated the grain yield characteristics are consistent. NX04Y2107 therefore is adapted to Great Plains agriculture, and will be proposed for release as a germplasm line in 2010. A second waxy winter wheat NX05M4180-6 was found to have resistance to multiple leaf rust races in seedling tests, and demonstrated good field resistance in south Texas nurseries. NX05MD4180-6 was descended from soft wheat parents, typically grown in the eastern and southern U.S. It will be entered in regional trials in the eastern states in the fall of 2009. Experiments were conducted to chemically modify waxy wheat starch, and blends of waxy wheat and normal wheat starch. Modified food starches are used in a variety of food products, including batters and sauces. It was determined that blending of waxy and normal starch can provide a wide range of functional properties, after chemical modification. Thus, food processors can now pre-determine the desired thickness of a particular sauce or gravy, and essentially develop any sort of starch functional properties necessary. There is increased domestic and foreign demand for hard white wheat from the Great Plains. Most current white cultivars suffer from two deficits – a lack of tolerance to pre-harvest sprouting, and moderate to high levels of grain polyphenol oxidase, an enzyme contributing to discoloration of fresh wheat products. Hard white wheat breeding lines with pre-harvest sprouting tolerances equal to that of the tolerant cultivar Nuplains were identified, and evaluated for resistance to field infections of leaf rust. Approximately 40 lines were identified as having both traits, and will be entered in a multi-location breeding trial to be seeded in Nebraska in the fall of 2009. Five populations segregating for 15 DNA markers putatively associated with pre-harvest sprouting tolerance were characterized for tolerance to pre-harvest sprouting. Nuplains HWW was identified as an excellent source of sprouting tolerance. In cooperation with the USDA Genotyping Lab in Manhattan, KS, we found Nuplains to carry the major sprouting genes also found in RioBlanco, a well-known source of sprouting tolerance. A number of progeny lines from Nuplains crosses carrying this trait. Also identified were spring wheats with essentially no polyphenol oxidase (PPO). High PPO levels lead to discolored food products. We can now eliminate this deficit, and have begun the process of introgressing the low PPO trait to hard white winter wheats. The unadapted spring wheats with the nil PPO trait were mated to several Great Plains adapted wheats in the spring of 2009.
1. Development of a waxy proso millet cultivar. Proso millet lines from China with waxy starch were identified, and, in cooperation with scientists at the University of Nebraska, used to develop the first waxy proso millet cultivar, known as Plateau, to be released in the United States. The development of Plateau has potential to expand the market and culture of proso millet in the western Great Plains. The waxy trait in proso millet was found to be under the control of two genes. This information is vital to proso millet breeders in future efforts to develop more and higher yielding proso millet cultivars.
2. Modified food starch from waxy wheat. Starches for food and industrial applications generally are chemically modified. Modified starch is used as a thickening agent, in many food products, and thickness is measured by a trait known as viscosity. Starch from waxy wheats was chemically modified by three procedures, and found to have dramatically enhanced viscosity after cooking, relative to normal wheat. In addition, final starch cooked viscosity was directly related to the percentage of waxy wheat in mechanical blends of waxy and normal wheat. Thus, food processors may use waxy wheat to achieve any desired final product texture.
Saito, M., Vrinten, P., Ishikawa, G., Graybosch, R.A., Nakamura, T. 2008. A novel codominant marker for selection of the null Wx-B1 allele in wheat breeding programs. Molecular Breeding 23:209-217 (2009).