2013 Annual Report
1a.Objectives (from AD-416):
Evaluate, identify, and develop sources of resistance to stem rust in wheat.
1b.Approach (from AD-416):
North Carolina State University will identify and obtain sources of stem rust resistance in cooperation with the USDA/ARS Plant Science Research Unit (PSRU), and other collaborating breeding programs. These sources of resistance will be used as parents in the breeding program to introgress stem rust resistance into advanced breeding lines of winter wheat. Top and/or backcrosses to adapted elite lines will be made to develop desirable segregating populations. When available molecular markers for known sources of stem rust resistance will be used to characterize parental lines and in marker assisted transfer and selection of resistance. Segregating populations developed from the introgressions will be inbred and advanced using traditional and/or marker assisted breeding methods when markers are available. Pure lines selected from advance breeding populations will be genotyped using available molecular markers and phenotypes for reaction to stem rust will be obtained in cooperative disease screening experiments conducted in field, greenhouse and/or growth chamber trials. Elite lines having stem rust resistance will be evaluated in regional and uniform yield nurseries, and superior lines will be released as cultivars. Data and germplasm will be shared between ARS, North Carolina State University, and other collaborating scientists. North Carolina State University and ARS-Raleigh will cooperatively develop rust-resistant wheat and barley germplasm having adaptation to Pakistan.
The researcj relates directly to inhouse objective to identify sources of resistance to stem rust and introgress resistance into adapted wheat.
Sources of stem rust resistant sources, developed by researchers in ARS-Raleigh, were introgressed into high yielding soft wheat lines from the North Carolina State University breeding program. Plants in segregating populations were selected for resistance to yellow rust and powdery mildew in North Carolina. These resistant lines were sent to Kenya for evaluation in the field to Ug99 wheat stem rust. All of our North Carolina-adapted experimental elite hard wheats were also tested in Louisiana, Georgia, Kentucky, Virginia, Maryland, Indiana, Arkansas, Texas, Oklahoma, Nebraska, and Washington State. Preliminary results from those locations indicated that the two lines have wide-adaptation in the U.S. Our elite materials, as well as all of our early-generation lines were tested for Ug99 stem rust resistance in Kenya. We are the only program in the world that has combined 4 genes for resistance to stem rust into single lines. We have been able to do this by shuttling segregating wheat populations between North Carolina and Kenya. We do this by selecting types with good agronomic performance in North Carolina, then selecting within those for resistance in Kenya. We then conduct genotyping in North Carolina for identification of specific stem rust resistance genes.
In addition, double-haploids were produced between ARS-Raleigh sources of rust resistance and wheat lines from Pakistan. These lines will be used for marker-assisted selection for stem rust resistance.