Organizing Committee


Poster Presentations


Poster Presentations


Reaction of selected common bean cultivars to various isolates of Phakopsora pachyrhizi

Presenter: M. A. Pastor-Corrales

All authors and affiliations: M. A. PASTOR-CORRALES (1), M. R. Miles (2), G. L. Hartman (2), and R. D. Frederick (3). (1) USDA-ARS, BARC-West, Vegetable Laboratory, Beltsville, MD 20705; (2) USDA-ARS, National Soybean Research Center, University of Illinois, Urbana, IL 61801; and (3) USDA-ARS, Foreign Disease-Weed Science Research Unit, Frederick, MD 21702

Soybean rust, Phakopsora pachyrhizi H. Sydow & Sydow, has been reported on common beans, Phaseolus vulgaris L., in Asia, South Africa, and the United States. However, there is little information on the interaction of individual isolates of P. pachyrhizi with common bean germ plasm. A set of 16 selected common bean cultivars with known genes for resistance to Uromyces appendiculatus (Pers.) Unger, three soybean accessions that were sources of the single gene resistance to P. pachyrhizi, and the moderately susceptible soybean ‘Ina’ were evaluated using seedlings inoculated with six isolates of P. pachyrhizi. Among the common bean cultivars, ‘Compuesto Negro Chimaltenango’, ‘Aurora’, ‘PI 181996’, and ‘Pinto 114’ were the most resistant to all six P. pachyrhizi isolates, with lower severity, less sporulation, and consistent reddish brown (RB) lesions associated with resistance in soybean. A differential response was observed among the common bean cultivars, with a cultivar by isolate interaction for both severity and sporulation levels, as well as the presence or absence of the RB lesion type. This differential response was independent of the known genes that condition resistance to U. appendiculatus, suggesting that resistance to P. pachyrhizi was independent from resistance to U. appendiculatus.

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