Location: Wheat, Sorghum and Forage Research2012 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.
3. Progress Report:
An investigation was conducted to determine whether the over-expression of specific gluten proteins can enhance bread quality in commercial-style sponge and dough baking procedures. The majority of mass produced bread arises from this method. The results demonstrated transgenic wheat can provide additional gluten strength in these applications without sacrificing final product appearance and volume. Transgenic wheat also can be used by millers to formulate flour samples with defined mix time requirements for automated systems, especially in crop years in which mix times might be depressed by adverse environmental conditions. Pre-harvest sprouting of wheat results in significant financial loss at all steps in the production and marketing chain. Due to its intermittent nature, direct selection for tolerance to pre-harvest sprouting is difficult. DNA markers linked to genes conditioning tolerance offer a more consistent and reliable approach to genetic improvement in tolerance. A study was undertaken to assess the value of previously identified markers linked to genes contributing to tolerance, using multiple genetic backgrounds. A significant contribution was demonstrated for QPhs.pseru-3AS, a gene previously identified from the hard white winter wheat Rio Blanco. DNA markers for this gene were associated with enhanced tolerance in three of four investigated backgrounds. In addition, positive contributions were documented for two additional genes, QPhs.pseru-2B1 and QPhs.pseru-2B2. As Rio Blanco has served as a parental line for much of the Great Plains hard white wheat gene pool, these markers will be widely used to develop sprout tolerant cultivars. Grain polyphenol oxidase (PPO) activity causes discoloration of wheat food products. Five breeding populations derived by crossing white wheats from the United States and Australia were selected to study the inheritance of PPO activity. A potentially novel gene that eliminates grain PPO was found in populations tracing to Australian wheats introduced in the 1930’s. Lines with these genes had the lowest mean PPO activities observed to date in common wheats. Winter wheats with nil levels of grain PPO were identified among the progeny of matings of these Australian spring wheats to U.S. winter wheats. The development of these super-low PPO lines demonstrates the tremendous value of the USDA-ARS National Small Grains collection. Wheat streak mosaic virus, and the recently discovered Triticum mosaic virus, depress wheat grain yields in the drier regions of the Great Plains. Wheat breeders have used two genes in attempts to develop resistant cultivars, Wsm-1, found in the USDA-ARS developed cultivar Mace, and Wsm-2. In field trials infected with Wheat streak mosaic virus, selections from the breeding line N02Y5149 were found to be as tolerant at triticale lines (generally assumed to be immune to these viruses), and superior to lines known to carry either Wsm-1 or Wsm-2. These breeding lines combine Wsm-1 with a potentially new source of resistance from a breeding line designated M08, and also appear to provide resistance to Barley yellow dwarf virus.