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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Stem Rust

Location: Wheat Genetics, Quality Physiology and Disease Research

2013 Annual Report

1a. Objectives (from AD-416):
Objective 1: Identify and characterize unique resistance sources from landraces that are amenable for introgression into adapted cultivars. Multiple new sources of resistance are important because resilient resistance to rusts has been problematic due to the rapid evolution of new virulent races within the fungi, this means that continuous efforts are essential to stay ahead of new emerging virulence. Objective 2: Identify molecular markers to facilitate both incorporation of resistance into adapted cultivars, and for marker assisted selection (MAS).

1b. Approach (from AD-416):
Germplasm from the USDA-ARS National Small Grains Germplasm Collection (NSGC) will be screened utilizing Amplified Fragment Length Polymorphism (AFLP) and Simple Sequence Repeat (SSR) markers for cladistic analysis. Caldistic analysis will be used to determine if stem rust resistant germplasm arose from a monophyletic origin or if multiple sources of novel resistance are represented within the germplasm collection. Develop genetic mapping populations to characterize resistance alleles to Ug99 in resistant cultivars. Documents SCA with Washington State University.

3. Progress Report:
This research relates to Parent Project 5348-21000-023-00D, Objective 2. The objective of the Specific Cooperator Agreement with Washington State University on the subject of stem rust, specifically UG99, is to develop pre-breeding tools for efficient introgression of new novel genes effective against UG99. Current results along these efforts include. 1) A molecular phylogeny of 733 landraces from the national small grains germplasm collection that had been screened in Kenya for resistance was developed. The purpose of this assay was to identify, based upon geography of origin and molecular profiles, novel UG99 resistance genes that can be introgressed into relevant breeding materials. 2) The above mentioned landraces were screened in Pullman and Mount Vernon, Washington; lines with resistance to all PNW stripe rust races were identified and incorporated into the molecular phylogeny (Sthapit, J Newcomb, M., Bonman, J.M., Chen, X., and See, D. 2012. Genetic Diversity for Stem and Stripe Rust Resistance in Wheat Landraces. Poster No. P0156. Plant and Animal Genome Conf. XX. January 14-18, 2012). Six mapping populations with both stem and stripe rust resistance have been developed using locally adapted germplasm. The parents of the 6 mapping populations have been genotyped; the mapping populations, currently in the F4 generation, have been phenotyped in the field at Whitlow farm in Pullman, 3 populations have adult plant resistance and 3 have seedling resistance. Genotyping of the mapping populations will start fall of 2013. 2) Fifty lines from the 733 landraces were assayed with the new 9,000 single nucleotide polymorphism (SNP) panel and the results of this assay are currently being evaluated in collaboration with scientist at the National Small Grains Germplasm Collection (NSGGC). Immediate impacts from this assay include two mapping populations that are being developed in the genotyping lab. These mapping populations will now include the relevant SNP markers in their genetic maps. Another impact is the association mapping of SNP markers for UG99 resistance. On the subject of stem rust research and discovery of new resistance sources, all results are communicated to the relevant research communities through meetings, frequent emails and conference calls. These include all discussions with principle investigator (PI) leading research and graduate students and post docs involved in the research.

4. Accomplishments

Last Modified: 06/24/2017
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