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United States Department of Agriculture

Agricultural Research Service


Location: Hard Winter Wheat Genetics Research

2012 Annual Report

1a. Objectives (from AD-416):
Develop elite hard winter wheat genotypes that incorporate multiple resistance genes that are effective against new African races of wheat stem rust.

1b. Approach (from AD-416):
Bread wheat germplasm lines with effective major gene and/or minor gene resistance against new African races of stem rust are being developed by USDA-ARS as well as many other institutions. These resistance donors will be crossed with multiple local elite breeding lines with high yield potential, grain quality, and tolerance to biotic and abiotic stresses. Good stewardship of valuable new resistance genes requires that they not be exposed singly in commercial cultivars. Endemic stem rust resistance genes, such as Sr24, Sr36, or Sr1A.1R, while very useful against most races, are not effective against all African races, and are not sufficient protection for new resistance genes. Therefore, the goal is to combine two or more new major genes into elite backgrounds. Minor gene or adult plant resistance genes are recommended as a supplement to major gene resistance. Minor genes are expected to be much more durable and do not require special stewardship protocols. In order to produce commercially competitive varieties of the future, new stem rust resistance genes must be incorporated into a forward breeding program. In addition, a backcross breeding program is required both for parent-building and as a hedge if commercially acceptable resistant varieties are needed in the short term. Rapid breeding methods, such as doubled haploids, will be needed to achieve results as quickly as possible. Phenotypic selection for resistance using common North American races will be difficult in most backgrounds due to the high frequency of endemic stem rust resistance genes. Therefore, marker-assisted selection for new resistance genes will be necessary. Molecular markers are available or under development for virtually all new sources of stem rust resistance. Marker genotypes will be generated locally or in a high throughput facility at the USDA-ARS Regional Small Grains Genotyping Laboratory in Manhattan, KS. Resistance of advanced lines against African races of stem rust will be confirmed by field testing at cooperative research facilities in Kenya or at the USDA-ARS Cereal Disease Laboratory. Testing for agronomic traits, yield, and quality will be performed as usual by the breeding program.

3. Progress Report:
The KSU wheat breeding program at Manhattan will be testing 20 F6 lines derived from the first Ug99 resistant materials in first year yield trials in 2013. Most of these lines are likely to contain single genes for resistance to Ug99. Approximately 50 F5 segregating populations that contain resistance to Ug99 will be planted for evaluation in 2013. Many of these populations have the potential to produce lines that carry multiple genes for resistance to Ug99. Individual plants will be selected from these populations for evaluation in 2014. We have several F4 populations that contain resistance to Ug99. Many of these contain ‘Kingbird’ in the pedigree. We have chosen to focus on partial resistance in our leaf and stripe rust resistance breeding so the use of Kingbird resistance is a logical fit with our overall rust resistance philosophy. We also have several F2 and F3 populations with Kingbird and will continue to focus primarily on pyramiding partial resistances. We are currently backcrossing Lr67/Sr55 and Lr34/Sr57 into twenty elite hard winter wheat backgrounds and intend to use these lines to complement the resistance found in Kingbird. The second backcross will be made on those lines in the Fall of 2012. Major gene efforts have primary been devoted to backcrossing into elite lines. Crosses of Sr40 with Sr35, Sr22 with Sr32 and Sr22 with Sr39 have been made. The double crosses will be made in the Fall of 2012 and the resulting progeny will be used to pyramid a minimum of three major genes into promising advanced lines.

4. Accomplishments

Last Modified: 10/15/2017
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