Identification of a Second Asian Soybean Rust Resistance Gene in Hyuuga Soybean

Authors

Mandy D. Kendrick, USDA-ARS Foreign Disease-Weed Science Research Unit
Donna K. Harris, University of GeorgiaFollow
Bo-Keun Ha, University of Georgia
D. L. Hyten, USDA-ARS, Soybean Genomics and Improvement Laboratory, Beltsville, MarylandFollow
P. B. Cregan, USDA-ARS, Soybean Genomics and Improvement Lab., Beltsville, MarylandFollow
Reid D. Frederick, USDA-ARS Foreign Disease-Weed Science Research UnitFollow
H. Roger Boerma, University of Georgia
Kerry F. Pedley, USDA-ARS Foreign Disease-Weed Science Research UnitFollow

ORCID IDs

D. L. Hyten

Date of this Version

2011

Citation

The American Phytopathological Society, Vol. 101, No. 5, 2011

Comments

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source.

Abstract

Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. Three isolates elicited different responses from soybean accessions PI 462312 (Ankur) (Rpp3) and PI 506764 (Hyuuga) (Rpp?[Hyuuga]). In all, 11 of the new accessions yielded responses identical to either PI 462312 or Hyuuga and 1 of the new accessions, PI 417089B (Kuro daizu), differed from all others. Additional screening of Hyuuga-derived recombinant inbred lines indicated that Hyuuga carries two resistance genes, one at the Rpp3 locus on Gm06 and a second, unlinked ASR resistance gene mapping to Gm03 (LG-N) near Rpp5. These findings reveal a natural case of gene pyramiding for ASR resistance in Hyuuga and underscore the importance of utilizing multiple isolates of P. pachyrhizi when screening for ASR resistance.