Objective:
The objectives of this cooperative field research are to: 1) evaluate approximately 774 germplasm accessions identified in seedling screens as potential sources of soybean rust resistance in containment greenhouse evaluations in the United States for adult plant resistance to soybean rust; 2) collect DNA from approximately 400 individual plants from four F2 populations (100 plants each) created from resistant/susceptible crosses and evaluate them for soybean rust resistance; 3) evaluate approximately 100 F3 lines from each of the 4 populations created by crossing resistant and susceptible parents, for resistance to soybean rust; and 4) evaluate approximately 500 F3 or F4 experimental lines for soybean rust resistance.

Approach:
Potential sources of resistance have been identified in the United States in a greenhouse evaluation, segregating populations created, and experimental lines developed. In Paraguay, these potential sources of resistance, segregating populations and experimental lines will be planted in an irrigated field environment and exposed to soybean rust. Plots will be monitored for occurrence of rust and data on the intensity of rust infection and defoliation will be recorded at various growth stages. Resistance data will be analyzed by US scientists to classify the potential resistant lines and the DNA samples will be used to identify molecular markers linked to resistance loci. The research directed toward identifying sources of resistance to soybean rust includes the following activities: a. Perform field trials of soybean varieties for resistance to soybean rust by planting seeds sent by ARS and evaluating the germplasm after inoculation with soybean rust, and b. Provide seed of soybean varieties in Paraguay that exhibit resistance to soybean to ARS for evaluation against soybean rust isolates in the USDA-ARS, Foreign Disease-Weed Science Research Unit collection at Ft. Detrick, MD.