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Genetics

Inheritance of Stripe Rust Resistance in Wheat Cultivars Postulated to Have Resistance Genes at Yr3 and Yr4 Loci. Xianming Chen,Research associate, Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; Roland F. Line, plant pathologist, Agricultural Research Service, U. S. Department of Agriculture, Pullman, WA 99164-6430. Phytopathology 83:382-388. Accepted for publication 17 December 1992. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1993. DOI: 10.1094/Phyto-83-382.

It has been postulated that wheat (Triticum aestivum) cultivars Cappelle Desprez, Druchamp, Hybrid 46, Minister, Nord Desprez, Stephens, Vilmorin 23, and Yamhill have genes for resistance to stripe rust at the Yr3 locus and/or the Yr4 locus. Seedlings of parents and F₁ and F₂ progeny from diallel crosses among the cultivars and of the eight cultivars crossed with Chinese 166 were tested for resistance to selected North American races of Puccinia striiformis. Seedlings of some BC₁ progeny also were tested. Yamhill has three resistance genes; the other cultivars have two resistance genes. Common loci were not detected in crosses of Hybrid 46 with Druchamp, Minister, or Stephens nor in crosses of Yamhill with Stephens. Minister, Cappelle Desprez, Druchamp, Nord Desprez, and Stephens have resistance genes at the Yr3 locus, but the gene at the Yr3 locus in Minister is different from the genes at the Yr3 locus in the other cultivars. Hybrid 46, Vilmorin 23, and Yamhill have resistance genes at the Yr4 locus, but the gene in Hybrid 46 is different from the genes at the Yr4 locus in Vilmorin 23 and Yamhill. The second resistance gene in Hybrid 46 is not at the Yr3 locus. Based on these results: Yr2 is in Yamhill; Yr3a is in Cappelle Desprez, Druchamp, Stephens, and Nord Desprez; Yr3c is in Minister; Yr3b is not in Hybrid 46 as previously reported; Yr4a is in Cappelle Desprez, Vilmorin 23, and Yamhill; and Yr4b is in Hybrid 46. In addition, stripe rust resistance genes not named previously were detected in Druchamp, Stephens, Nord Desprez, Vilmorin 23, Yamhill, Minister, and Hybrid 46. These genes are designated provisionally as YrDru, YrSte, YrND, YrV23, YrYam, YrMin, and YrH46. Expression of dominance or recessiveness of resistance genes changed in many of the cultivars, depending on the race used in the test. Various epistatic interactions were observed also. Differences in resistance were observed in some reciprocal crosses, which suggests that there are maternal cytoplasmic effects on the expression of resistance by the genes.