Location: Wheat, Sorghum and Forage Research2011 Annual Report
1a. Objectives (from AD-416)
The main objective of this project is to develop improved winter wheat and barley germplasm and cultivars with stem rust resistance that will be winter-hardy with high yield and end-use quality, environmentally stable in production, and provide an increased return per grower input. Stem rust resistant plant materials adapted to both conventional and organic production systems will be developed.
1b. Approach (from AD-416)
Crosses will be made in the greenhouse using selected wheat and barley germplasm parents possessing various combinations of adequate winter-hardiness and heat and drought tolerance, high yield, resistance to Ug99 stem rust and other races of rust prevalent in the northern Great Plains, other disease and insect resistance or tolerance, improved end use quality attributes, and good straw strength. Germplasm will include locally adapted lines and cultivars, introduced materials from private programs, other regions or countries having unique characteristics, and, when necessary, derivatives from related species and genera developed by more basic germplasm programs. Marker assisted selection will be used for allele enrichment in the early generations and genotyping advanced lines for line characterization. F1 seed will be increased in the greenhouse or Yuma, AZ to create a large number of populations of ample size. F2 and F3 populations will be grown at Lincoln or Mead, NE. F3 derived lines will continue to be selected with statewide testing beginning in the F6. Field testing will be supplemented with greenhouse testing for leaf and stem rust testing at Lincoln, NE and St. Paul, MN (USDA ARS Cereal Disease Laboratory). Standard and molecular genetic analytical procedures to determine the inheritance of the traits that are useful to enhance adapted cultivars. Agrobase GenII software, SAS or GENSTAT will be used to analyze data.
3. Progress Report
Wheat stem rust can incite some of the most devastating disease epidemics. Severe outbreaks of stem rust were common in the U.S. Great Plains in the years before 1960. The use of naturally occurring genes conferring resistance in wheat cultivars deployed since that time has effectively prevented any such re-occurrences. The evolution in Africa of new virulent races of stem rust, specifically various forms of Ug99, however, threatens the stability of U.S. wheat production. Many currently grown cultivars are susceptible to these new races. The goal of this project is to develop wheat cultivars with both resistance to these new, more virulent stem rust races, and adaptation to Nebraska and other northern Great Plains states. Over 2000 wheat breeding lines at various stages of development were screened in the greenhouse, using a surrogate race approach that allows forecast of potential resistance to Ug99. Crosses were made between Nebraska-developed wheats and an international collection of lines carrying several new genes conferring resistance to Ug99. Genes used include: Srtmp, Sr39, Sr2, Sr25, SrCadillac, as well as other unknown minor genes from the International Maize and Wheat Improvement Center (CIMMYT). These genes are being combined with the previously used genes Sr6, Sr24, Srtmp, SrAmigo, and Sr36. The goal is to pyramid genes to build a stronger base of resistance among advanced breeding materials. Thirty elite triticale breeding lines and 40 elite winter barley lines were evaluated for field resistance to stem rust race TPMK. Triticale lines from South Africa, with resistance to Ug99, were obtained, and crosses were made with Nebraska adapted triticales. Future plans include testing all advanced wheat, triticale and barley breeding lines possessing new and multiple stem rust resistances in Kenya, in order to evaluate their response under natural Ug99 infestations. This approach will insure a steady supply of stem rust resistant cultivars for the entire Great Plains wheat production and utilization industry. ADODR monitoring is accomplished via phone calls, e-mails and personal contact at professional meetings and during site visits.