Researchers at the University of Illinois at Urbana-Champaign and United States Department of Agriculture - Agricultural Research Service (USDA-ARS) have discovered a gene for soybean aphid resistance in the soybean cultivars Dowling and Jackson. The soybean aphid was identified in the Midwestern United States as a significant infestation in July of 2000 and has since expanded to twenty-one states and other parts of North America. This soybean production threat has the potential to decrease yields through plant damage such as stunting, leaf distortion, and reduced pod set in soybean plants. In addition, the soybean aphid is capable of transmitting viral diseases that naturally infect soybean plants.

The University of Illinois and USDA-ARS have identified and mapped the first genetic locus, designated Rag1 (proposed), which conditions resistance to the soybean aphid. Furthermore, methods for identifying and breeding resistant plants by marker-assisted selection (MAS) have been developed.

Scientists at the University of Illinois at Urbana-Champaign together with scientists from the USDA-ARS evaluated 100 cultivars that account for nearly 90% of the genetic variety in US soybeans and subsequently identified 3 different cultivars that show resistance to soybean aphids. The gene conferring resistance has been mapped and tentatively designated Rag1. Rag1 has been tested in greenhouse and field and has consistently prevented soybean aphid colonization. Because it is a single dominant gene, with identified DNA markers, it can be readily introgressed into aphid-susceptible commercial soybean germplasm by backcrossing using marker assisted selection.

The technology available for license is a method for determining the presence or absence of Rag1 in a soybean germplasm and a method for producing an inbred soybean plant selected to confer soybean aphid resistance. 

Benefits

• Rapid, straight-forward introgression of Rag1 source of aphid resistance into susceptible soybean cultivars by MAS. 
• Prevents successful aphid colonization on plants by reducing aphid multiplication, survival, lifespan, and development of nymphs to adults.
• Deters aphids from feeding on plants containing the gene.
• Reduces the need to apply insecticides to control aphids, thereby reducing the input costs for soybean producers and the impact on the environment.