Progress 09/01/02 to 08/31/07
Outputs
Progress Report Objectives (from AD-416) Conduct growth chamber and greenhouse experiments to develop and optimize a bioassay for identifying and characterizing resistance to the bird cherry-oat aphid (BCOA) in wheat and barley. This bioassay will be used to test large germplasm collections to find new sources of resistance for developing improved BCOA resistant germplasm and for analyzing the genetic control of that resistance. Approach (from AD-416) The impact of BCOA feeding on wheat and barley seedling root and shoot growth rates will be measured using a modified root bioassay. This bioassay will focus on the visualization of root systems (using root pouches or a hydroponics system) to determine BCOA feeding effects not readily detected in above ground seedling growth. The differences detected in relative growth rates among germplasm entries will be analyzed to find accessions less affected by BCOA feeding. Select lines displaying tolerance to BCOA feeding will undergo further testing for agronomic performance under BCOA infestation to confirm seedling test results. Significant Activities that Support Special Target Populations This report serves to document research conducted under a specific cooperative agreement between the ARS and Oklahoma State University, Stillwater. Additional details of research can be found in the report for the parent CRIS 6217-21000-006-00D, Genetic Improvement of Insect Pest Resistance in Wheat, Barley, and Sorghum. Recombinant-inbred line populations are under development using parents previously identified to have divergent reactions to bird cherry-oat (BCO) aphids in controlled bioassays. These populations will be used to study the inheritance and expression of BCO tolerance in hard winter wheat. Breeding populations continue to be developed in the collaborative OSU wheat improvement program via exposure to natural field infestations of bird cherry-oat aphid in early-planted management systems. Tolerance is selected indirectly based on responses to barley yellow dwarf (BYD) virus. 'Duster' hard red winter wheat, a cultivar jointly released with USDA-ARS in 2006, exhibits a moderate and desirable level of BYD tolerance in the field. ADODR monitored activities through monthly meetings.
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Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Oklahoma State University. Additional details of research can be found in the report for the parent CRIS (6217-21000-006-00D, Genetic Improvement of Insect Pest Resistance in Wheat, Barley, and Sorghum). Bird cherry-oat aphid (BCOA) tolerant wheat breeding lines were identified using a newly developed and optimized seedling bioassay. This bioassay is based on growing wheat seedlings in clear plastic root pouches to allow visual examination of root and shoot growth during BCOA infestation. Using the root pouch protocol, BCOA-infested seedlings can easily be compared to non-infested seedlings to determine the negative effect of aphid feeding on root and shoot growth rates. Growth rates of several wheat breeding lines can be compared under BCOA infestation to identify those with the highest levels of tolerance to aphid feeding.
Using this approach, a core collection of BCOA-tolerant wheat lines was identified for additional work. Select wheat lines with the highest levels of tolerance were used in a crossing program to transfer BCOA tolerance gene(s) to adapted high performance wheat breeding lines. Progeny from these crosses will be used for genetic analysis of BCOA tolerance, and for further testing and selecting for future cultivar development.
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Progress 10/01/04 to 09/30/05
Outputs
4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Oklahoma State University. Additional details of research can be found in the report for the parent CRIS (6217-21000-006-00D, Genetic Improvement of Insect Pest Resistance in Wheat, Barley, and Sorghum). A new improved seedling bioassay developed recently under this agreement was utilized in a study to attempt to confirm previous selections of bird cherry-oat aphid (BCOA) tolerance within wheat. The previous selection procedure was based on a visual assessment of root and shoot growth rate differences among seedling wheat entries when challenged by BCOA. A select group of wheat cultivars obtained from the USDA-National Small Grain Collection were tested using the new seedling root pouch bioassay. Results obtained from this study partially confirmed previous results obtained by visual assessment only. Some wheat cultivars were rated tolerant
to BCOA feeding using both assays, while others were identified as less tolerant using the root pouch assay than were judged by visual assessment only. The results indicated that the root pouch assay, while more cumbersome to deploy, should be more reliable in identifying BCOA tolerance differences among wheat germplasm.
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Progress 10/01/03 to 09/30/04
Outputs
4. What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a specific cooperative agreement between ARS and Oklahoma State University. Additional details of research can be found in the report for the parent CRIS (6217-21000-006-00D, Genetic Improvement of Insect Pest Resistance in Wheat, Barley, and Sorghum). An improved bioassay used to detect wheat seedling tolerance to bird cherry-oat aphid feeding was developed. The bioassay utilizes a root pouch system to detect aphid-feeding effects on root and shoot development rates following aphid infestation. Infested wheat seedlings are compared to non-infested seedlings to determine the relative reduction of growth rates caused by aphid feeding. Utilizing this bioassay, several collections of winter wheat cultivars, breeding populations, and germplasm were tested for their reaction to bird cherry-oat aphid feeding. Several cultivars
showing high levels of tolerance to aphid feeding were identified. These cultivars showed similar, and in some cases higher, levels of shoot and/or root growth in infested seedlings as compared to non-infested seedlings. These seedlings will now serve as sources of bird cherry-oat aphid tolerance for developing improved cultivars.
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