Project Number: 5012-22000-021-11-S
Project Type: Specific Cooperative Agreement
Start Date: Jun 4, 2012
End Date: Mar 31, 2015
The overall objective of the project “Identification and Utilization of Resistance to Soybean Rust” is to identify and develop soybean germplasm with broad resistance to Phakopsora pachyrhizi, the cause of soybean rust (SBR). Characterization of virulence diversity among P. pachyrhizi populations and the reactions of resistant lines are important to guide breeding for effective and durable resistance. Specific objectives will be to (1) identify resistant plant introductions (PIs) from the USDA Soybean Germplasm Collection; and (2) map and transfer resistance genes to germplasm adapted to the U.S.
Objective 1 will be addressed by testing soybean germplasm accessions from the USDA-ARS Soybean Germplasm Collection and breeding lines developed from crosses made with those accessons for resistance to soybean rust (Phakopsora pachryhizi) in the field and greenhouse. Due to demonstrated ability of the rust pathogen to evolve and to evidence that multiple pathotypes and virulence groups already exist in the southern U.S., it will be important to confirm the resistance of historically resistant accessions as well as identifying additional sources of novel resistance genes. This will be done annually in locations in the southern U.S. through the assistance of collaborators. The Rpp (Resistance to Phakopsora pachyrhizi) genes responsible for the resistance in these accessions would then need to be characterized by developing lines and populations that can be used to map their locations in the genome and study their effects both singly and in combination with other Rpp genes. This information will be important to allow breeders to decide which genes to combine to achieve broader and more durable resistance. Assessments of genetic and pathogenic diversity within and among populations of the rust fungus are important to develop effective breeding and management strategies, so the third objective of this project will be to collect and characterize isolates of the rust fungus that have been collected in different years and locations. The germplasm screening nurseries established to meet Objective 1 would provide sources of contemporary isolates, and colleagues in areas that experience soybean rust epidemics are likely to submit local samples of SBR as well. Isolates from field populations will be pathotyped using a set of differential lines and will also be characterized genetically using DNA markers.