2008 Annual Report
1a.Objectives (from AD-416)
The overall goal of this research plan is to identify and characterize genes that can be used to improve disease resistance in wheat. Four objectives will address this goal. Objective 1: Use marker-assisted selection to introduce new Fusarium head blight (FHB) resistance into hard red spring wheat. Objective 2: Use transcript profiling and virus-induced gene silencing (VIGS) to identify wheat genes involved in resistance to rust pathogens. VIGS will be completed in collaboration with Steve Scofield, ARS West Lafayette, Indiana. Objective 3: Use the model plant Brachypodium distachyon (Brachypodium) to identify and validate genes involved in stem rust resistance in wheat. Objective 4: Coordinate the Uniform Regional Performance Nursery for Spring Wheat Parents. Wheat improvement is a balancing act because it requires the simultaneous selection of multiple diverse traits to develop superior new cultivars. Two of the three diseases that are subjects of investigation here (FHB, leaf rust) presently cause economic losses to the U.S. wheat crop, while the third disease (stem rust) has the potential to do so. By taking a multidisciplinary approach to improving wheat disease resistance as proposed in this research plan, multiple avenues for protecting wheat against these three diseases will become available. Providing strategies, knowledge, and tools for improving wheat disease resistance, as delineated by the first three objectives, will lead to reduced yield losses attributable to FHB and leaf rust, and will ensure that the potential disease threat from stem rust can be addressed proactively. The fourth objective subsequently provides an opportunity for all spring wheat breeders to evaluate the overall performance of advanced germplasm, including assessment of resistance to FHB, leaf rust, and stem rust, in addition to overall agronomic quality.
1b.Approach (from AD-416)
Wheat is the most widely grown crop in the world and is a major staple crop for humans. Wheat is economically very important to the United States, which ranks third among all countries in wheat production and is the world's largest wheat exporter. Despite its importance as a crop, low prices that are generally paid for wheat grain result in small profit margins for producers. Further, both abiotic and biotic stresses can cause significant fluctuations in U.S. wheat production. Reducing wheat losses associated with the fungal diseases Fusarium head blight, leaf rust, and stem rust will enhance both the stability and profitability of U.S. wheat production. This research project seeks to contribute to the goal of controlling these three diseases by completing integrated genetic, molecular genetic, and genomics research that will further our understanding of genes and underlying molecular processes in wheat that are involved in resistance to each of these diseases. The results of this research will provide both new resources and new knowledge that can be used to increase resistance to each of these three diseases in wheat. This will lead to improved wheat yield and yield stability and will ensure that the U.S. wheat crop is protected against current and future disease threats.
Resistance characterization of wheat near-isogenic lines developed to contain different Fusarium head blight resistance genes is being pursued. In summer 2008, we completed what we expect to be the last series of Fusarium head blight resistance evaluations in wheat lines that theoretically differ principally by the presence or absence of one of five different genes conditioning Fusarium head blight resistance. We also have collaborators undertaking the same evaluations in other locations. These data should provide the last experimental data needed to make decisions about which of the genes individually confer some resistance and thus are amenable to gene pyramiding studies. A project to improve Fusarium head blight resistance in the forage grain triticale is advancing. We have begun vernalizing seedlings of triticale back-cross 2 (BC2) families that are expected to be segregating for a major Fusarium head blight resistance gene from the wheat line Sumai 3. Our research with the model grass Brachypodium distachyon continues. This has included developing segregating F2 populations from crosses between the main inbred line of Brachypodium, which we developed several years ago, and a line collected in Spain. Putative new F1 hybrids were developed from crosses between three different inbred genetic stocks. (NP 301, Components 2 (Problem Statements 2B and 2C) and 3 (Problem Statements 3A, 3B, and 3C))
5.Significant Activities that Support Special Target Populations