Skip to main content
ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #378978
Research Project: Identification, Biology, Epidemiology, and Control of Foreign and Emerging Fungal Plant Pathogens

Location: Foreign Disease-Weed Science Research

Title: Phenotypic reactions of 53 soybean genotypes to infection with each of 16 isolates of Phakopsora pachyrhizi

Author
item Stone, Christine
item SMITH, JAMES - US Department Of Agriculture (USDA)
item RAY, JEFFREY - US Department Of Agriculture (USDA)
item GILLEN, ANNE - US Department Of Agriculture (USDA)
item Frederick, Reid

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2021
Publication Date: 3/29/2021
Citation: Stone, C.L., Smith, J.R., Ray, J.D., Gillen, A.M., Frederick, R.D. 2021. Phenotypic reactions of 53 soybean genotypes to infection with each of 16 isolates of Phakopsora pachyrhizi. Journal of Crop Improvement. https://doi.org/10.1080/15427528.2021.1904311.
DOI: https://doi.org/10.1080/15427528.2021.1904311

Interpretive Summary: Soybean is the most important legume grown in the United State used for food, feed, and fuel. A devastating disease, caused by the fungal pathogen Phakopsora pachyrhizi, occurs on soybeans worldwide. While fungicides are available that control the disease, the pathogen has developed tolerance to some fungicides. To assess for resistance to soybean rust, this study examined 53 soybean genotypes infected with 16 different isolates of the fungal pathogen collected throughout the world. The previously identified rust resistance gene, Rpp1, was found 18 of the soybean lines tested. Two soybean lines were found to contain two soybean resistance genes, Rpp2 and Rpp4, while another soybean line possessed the resistance genes Rpp1b and Rpp4. Three soybean lines were identified as having possible new sources of resistance to soybean rust. The resistance identified in these soybean lines could be used as sources to develop high yielding soybean lines with broader resistance to soybean rust.

Technical Abstract: Soybean rust, caused by the fungal pathogen Phakopsora pachyrhizi, is an economically significant disease for soybean production throughout the world. Resistance to P. pachyrhizi (Rpp) genes have been identified at multiple loci in the soybean genome, but each conditions resistance to specific P. pachyrhizi isolates rather than providing broad resistance to the species. Identifying soybean cultivars with previously unidentified Rpp genes combined with efforts to breed soybean containing multiple Rpp genes is a key part of the ongoing strategy to manage the disease and minimize its economic impact. Fifty-three soybean genotypes, possessing known and unknown Rpp genes, were challenged with 16 P. pachyrhizi isolates from a global collection. The observed phenotypic reaction patterns provided insight into the presence of Rpp genes. This study tentatively confirms the presence of Rpp1b, or an allele, in eleven soybean lines of previously unknown resistance gene, and in another seven lines produced by targeted breeding. Examples of resistance gene pyramiding were identified in lines 4014-242-341 and 4018-4-1-1-212, which may contain both Rpp2 and Rpp4 genes and line RN6-313-362, which may contain both Rpp1b and Rpp4. Three possible sources of new resistance genes may exist within GC00138-29, PI 567145C, and PI 605833.