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United States Department of Agriculture

Agricultural Research Service

Research Project: Northwest-Adapted Barleys for Resistance to Stem Rust (Ug99)

Location: Forage Seed and Cereal Research

2012 Annual Report


1a.Objectives (from AD-416):
Produce F3 populations of Northwest-adapted barleys crossed with sources of genes for resistance to the Ug99 stem rust pathogen.


1b.Approach (from AD-416):
Make crosses between Ug99-resistant barley lines and various market types of barley adapted to Pacific Northwest production. The Ug99 resistant lines will be from ICARDA/CIMMYT material previously tested by Brian Steffenson at University of Minnesota, and the locally-adapted lines will include winter barley of malting, food and forage types. Conduct field evaluations of F2 populations for agronomic traits including cold tolerance and resistance to local diseases, then advance to the F3 generation for further testing. The materials resulting from this SCA will be available for further development and testing to select materials that are locally adapted and have resistance to Ug99. This SCA supports research conducted under National Program (NP) Number303, Plant Diseases. The research is conducted as part of ARS research project 5358-22000-035-00D, augmented by the FY2010 Program Increase for Research to Strengthen Grain Disease Research to Reduce World Hunger.


3.Progress Report:

This project is one of three Specific Cooperative Agreements (SCAs) that support the in-house parent project's Objective 1C: Identify germplasm and increase seed for wheat and barley lines with resistance to stem rust Ug99. In particular, this SCA conducts research supporting the national Ug99 barley breeding effort by evaluating Ug99-resistant lines for agronomic adaptation to Pacific NW conditions, and by producing derivative barley populations for further UG99 resistance assessment. The UG99 resistance germplasm developed in previous funding cycles was advanced in the field at Corvallis, Oregon. Seventeen F2 populations of ~ 5,000 plants each - effectively a resource of ~ 80,000 individuals – were grown. F3 heads were selected based on resistance to local diseases (principally stripe rust, leaf rust and scald) as well as reproductive fitness traits (kernels/spike and kernel size). The selected F4s will be planted in head rows at Corvallis in October of 2012 and sent to Africa for UG99 testing. The South African UG99 nursery conducted in 2011 by cooperators at the University of Minnesota did not generate useful data for selecting segregating progeny due to climatic conditions unfavorable for stem rust epidemic development. Data on the elite accessions tested in Africa for UG99 resistance in 2011/2012 (courtesy of USDA/ARS) have not yet been received. In July 2012 we received confidential information on a cloned gene conferring resistance to UG99 in barley. We are permitted to use the resistant germplasm in crosses – seed is in transit. The resistant accessions will be crossed with local elite germplasm in the fall of 2012 and backcrossed in the winter of 2012/2013. Based on the sequence of the cloned gene conferring resistance, we will be able to implement marker assisted selection on the BC1F1 progeny. With additional resources we will be able to produce doubled haploids from selected BC1F1 plants, genotype the resulting doubled haploids and advance only homozygotes for the resistance gene to field trials. If the additional resources for doubled haploid production are not forthcoming, we will advance the selected BC1F1 plants to BC1F2 by selfing. Selected resistant homozygotes (full genome for doubled haploids; target gene for selfed progeny) will be available for UG 99 testing in Africa in 2013.


Last Modified: 7/12/2014
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