2012 Annual Report
1a.Objectives (from AD-416):
The main objective of this project is to develop wheat germplasm with genes for resistance to stem rust race Ug99 and currently encountered races of wheat stem rust. Attention will focus on the introduction of new genes to Great Plains adapted wheats, and pyramiding these genes with genes for resistance to additional pathogens.
1b.Approach (from AD-416):
The USDA-ARS Grain, Forages and Biofuels Research Unit at Lincoln, NE, is developing Great Plains adapted winter wheat germplasm with resistance to Ug99 and other races of stem rust. Stem rust resistance is being pyramided with genes conferring resistance to additional pathogens, including leaf and stripe rusts, and wheat streak mosaic and soilborne mosaic viruses. The Department of Plant Pathology at the University of Nebraska will identify breeding lines carrying stem rust resistance. Newly developed wheat breeding lines (F5 or F6 generations) derived from crosses with resistant donor parents will be assayed for stem rust resistance at the seedling stage via inoculations in the greenhouse, and for adult plant resistance, after inoculation at the University of Nebraska Agricultural Research and Development Center near Mead, NE.
The primary goal of the USDA-ARS Wheat Genetics project at the University of Nebraska is the development of wheat breeding lines with enhanced end-use quality and resistance to viral pathogens. The presence of resistance to wheat stem rust further guarantees successful use of these materials, either as parental lines in wheat breeding programs or as cultivars. Approximately 150 advanced breeding lines were tested in the greenhouse against two stem rust races, TPMK and QCFS, two races that can serve as surrogates and identify lines with resistance to Ug99, the highly virulent race recently arisen in East Africa. Approximately 40 lines with seedling resistance to both races were identified. Lines originally were developed to have enhanced tolerance to pre-harvest sprouting, resistance to Wheat streak mosaic virus, or a type of altered starch with enhanced properties for industrial uses. Two of the sprouting tolerant lines were entered in the 2012 USDA-ARS coordinated Northern Regional Performance Nursery, and also were tested in the University of Nebraska Organic Wheat yield trials in 2012. Several lines derived from re-selection of the breeding line N02Y5149 were found to be resistant to both TPMK and QCFS stem rust, and to have field resistance to both Wheat streak mosaic virus and Barley yellow dwarf virus. The two top yielding re-selections will be advanced to further yield testing in 2013. Six wheats with altered (waxy) starch were found to be virtually immune to both TPMK and QCFS. These wheats presently are being tested in Kenya for resistance to Ug99. Any that retain resistance in Kenya will be advanced to the USDA-ARS coordinated Northern Regional Performance Nursery. Even though these waxy wheats are being developed for use in the modified food starch industry, their stem rust resistance will also be useful to breeders of conventional quality wheats.