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Comparison of virulence and isozyme phenotypes of Pgt-QCCJ and Great Plains races of Puccinia graminis f.sp. tritici

Roelfs, A.P., McCallum, B., McVey, D.V., Groth, J.V.
Phytopathology 1997 v.87 no.9 pp. 910-914
phenotype, Hordeum vulgare, Puccinia graminis, Triticum aestivum, plant pathogenic fungi, genetic techniques and protocols, genes, genetic variation, pathotypes, isozymes, virulence, protein composition
Stem rust race Pgt-QCCJ was first found in the Great Plains of the United States in 1989, collected primarily from barley. This race became a major part of the Puccinia graminis f. sp. tritici population, even though it is virulent to only a few hard red winter wheat cultivars in the central Great Plains and to barley in the northern Great Plains. It threatens barley production in the northern Great Plains of the United States and Canada due to virulence to Rpg-1. Six differences in virulence and two in isozyme banding patterns from the most similar stem rust races make it unlikely that QCCJ arose as a mutant. Thus, QCCJ likely arose through sexual or parasexual recombination. Sexual recombination in the Great Plains is unlikely, as it has not been detected in many years. Avirulence to 'McNair 701' is only known from the Pacific Northwest of the United States and adjacent Canada. The rust population in this area is of sexual origin, and the pattern of virulence/avirulence and isozyme banding for QCCJ occurs there. Pgt-QCCJ likely originated in the Pacific Northwest during or before 1989 and was wind-transported into the Great Plains.