• New multi-biotype resistance genes. This project will identify, characterize, and map the location of at least one newly identified soybean gene that gives resistance to biotypes 1, 2, 3. This gene and information on its map location will be made available to soybean breeders.
• Markers associated with multi-biotype resistance. At least one soybean markers linked to a newly identified multi-biotype resistance gene will be identified. Information on the linked marker will facilitate the development of new soybean cultivars with wide-spectrum aphid resistance using marker-assisted selection breeding procedures.
• Markers associated with soybean aphid virulence. At least one aphid marker closely associated to virulence on a Rag gene will be identified. Use of this virulence-associated aphid marker will help determine potential for aphids in samples collected in specific areas to attack plants with the Rag gene. Information on virulence potential will help maximize the effectiveness of soybean aphid management with resistance by guiding stakeholders, such as seed company and extension entomologists, on where cultivars with Rag genes should be deployed for maximum effectiveness, and soybean grain producers on selecting soybean cultivars with appropriate Rag genes for their area. Use of the virulence-specific markers will enable a novel strategy to manage soybean resistance genes that could maximize resistance and lengthen the time of effective service of Rag genes.

Achieving the objectives
- Six PI accessions found to be resistant to biotype 1, 2 and 3 aphids in earlier studies were shown to be resistant to biotype 4 as well, indicating the these PI lines are exhibiting different Rag alleles for Rag1 and Rag2 than earlier resistance sources.
- Clones from biotype 2 x 1, 2 x 3 and 3 x 2 crosses were established in field buckthorn cages.
- Three field-collected aphid isolates were tested and determined to colonize Williams 82, Rag1 and Rag2 lines, indicating that all three exhibited biotype 4 virulence.
- Will attempt to mate soybean aphid with nastursium and cotton-melon aphids since they all use the same buckthorn over-wintering host in an effort to see whether hybridization could be impacting virulence.
- Three lines with rag1c and rag4 resistance from PI 567541B were selected for advanced evaluation of agronomic performance in 2015.
- The rag1c and rag4 resistance genes from PI 567541B and Rag3 from PI 567543C were fine-mapped within genetic intervals less than 100 kb.
- An experimental protocol has been developed to isolate biochemicals associated with aphid virulence against specific soybean aphid resistance genes.