1a.Objectives (from AD-416):
Find associations between molecular polymorphism (Single Nucleotide Polymorphism) with leaf rust and stem rust resistance in diverse wheat germplasm in order to find new genes for leaf rust and stem rust resistance in wheat.
1b.Approach (from AD-416):
Test wheat germplasm (6,0000 entries) from core collection at NSGC-USDA-ARS Aberdeen for resistance to wheat leaf rust in greenhouse and field plot tests. Spring wheat lines (ca. 2500) will be grown in St. Paul, Minnesota and evaluated for field resistance over two years to a mixture of current leaf rust races. 2,500 winter wheat lines will be evaluated over two years in plots at Castroville, Texas. 500 entries selected for drought tolerance, and 500 entries selected for leaf rust resistance will also be tested for resistance in field plot tests. All entries will be tested as seedling plants in greenhouse tests with a mixture of leaf rust races to determine the presence of effective seedling resistance genes. Phenotype data from field plot tests and seedling tests will be used to determine which entries have effective adult plant resistance and which have effective seedling resistance. The rust data will be combined with the single nucleotide polymorphism genotype data for all entries generated by USDA-ARS Wheat genotyping labs for association mapping to identify new genes for leaf rust resistance.
This project addresses the societal and scientific challenges of mitigating the negative effects of climate change on crop production. Our research contributes to the long-term objective of a 10% reduction in both nitrogen and water use in barley and wheat production through the development of improved varieties that are better adapted to changing environments, and improved for rust resistance. Five thousand spring and winter wheat cultivars will be evaluated for leaf rust and stem rust resistance in field plots and in greenhouse tests to specific rust races. The phenotype data is to be combined with single nucleotide polymorphism (SNP) genotyping using a recently developed 5,000 SNP to map the genomic locations of rust resistance in wheat through association mapping. In 2012-13, 2,000 spring wheat lines, and 650 winter wheat lines were evaluated for leaf and stem rust resistance in greenhouse and field plot tests.