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.