Skip to main content
ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #223674
Title: Differential Responses of Resistant Soybean Genotypes to Ten Isolates of Phakopsora Pachyrhizi

Author
item PHAM, T - UNIV OF ILLINOIS
item Miles, Monte
item Frederick, Reid
item HILL, C - UNIV OF ILLINOIS
item Hartman, Glen

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2008
Publication Date: 3/1/2009
Citation: Pham, T.A., Miles, M.R., Frederick, R.D., Hill, C.B., Hartman, G.L. 2009. Differential Responses of Resistant Soybean Genotypes to Ten Isolates of Phakopsora Pachyrhizi. Plant Disease. 93:224-228.

Interpretive Summary: Soybean rust, caused by the fungus Phakopsora pachyrihizi, was detected in the continental U.S in 2004. Some sources of resistance have been identified; however, information about the stability of these new sources of resistance to a number of isolates of the pathogen is not known. In this study, ten P. pachyrhizi isolates were used to inoculate a set of 20 soybean genotypes. Soybean genotypes varied in their reaction types from fully susceptible to resistant. Isolates Taiwan 72-1 and Alabama 04-3 caused the greatest frequency of tan lesions over all 20 genotypes. Many of the new sources of rust resistance, not yet genetically characterized, had different reaction patterns among the 10 isolates compared to the four accessions with known resistance genes. This information is useful for soybean pathologist, breeders and other scientist that study the interaction of plants and microbes.

Technical Abstract: Soybean rust, caused by the fungus Phakopsora pachyrihizi, was detected in the continental U.S in 2004. Some sources of resistance have been identified; however, information about the stability of these new sources of resistance to a number of isolates of the pathogen is not known. In this study, ten P. pachyrhizi isolates were used to inoculate a set of 20 soybean genotypes. These genotypes included two susceptible checks, four sources of the single genes (Rpp1-4), four resistant genotypes selected from field trials in Paraguay, and 12 resistant genotypes identified from field trials in Vietnam. Susceptible checks all had tan lesions. All other genotypes had differential responses except for PI 459025B (Rpp4) that had red-brown lesions to all isolates. Isolates Taiwan 72-1 and Alabama 04-3 caused the greatest frequency of tan lesions over all 20 genotypes. Many of the new sources of rust resistance, not yet genetically characterized, had different reaction patterns among the 10 isolates compared to the four accessions with known Rpp genes, indicating that they may be new sources of resistance genes.