VIEW ARTICLE

Resistance

A New Major Gene for Resistance to Phytophthora megasperma var. sojae in Soybean. K. L. Athow, Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; F. A. Laviolette(2), E. H. Mueller(3), and J. R. Wilcox(4). (2)(3)Associate professor, and graduate assistant, respectively, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; (4)Professor, Department of Agronomy, and research geneticist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture (AR, SEA, USDA), Purdue University, West Lafayette, IN 47907. Phytopathology 70:977-980. Accepted for publication 6 April 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-977.

The inheritance of resistance to Phytophthora megasperma var. sojae was studied in the F₂ and F₃ generations from crosses of the soybean plant introduction (PI) 86050 with Harosoy (rps₁ rps₃), Mukden (Rps₁ rps₃), PI 84637 (Rps₁^b rps₃), PI 54615-1 (Rps₁^c rps₃), PI 86972-1 (rps ₁ Rps ₃), and Altona. The data indicate that PI 86050 has two genes for resistance to races 1, 2, and 3; one gene for resistance to races 4, 6, 7, 8, and 9; and no gene for resistance to race 5. The results show that one of the genes in PI 86050 is Rps₁^c which conveys resistance to races 1, 2, 3, 6, 7, 8, and 9. The other gene conveys resistance to races 1, 2, 3, and 4. The symbol Rps₄ is proposed for this gene. Rps₄ is not at the same locus as the allele in Altona which also controls resistance to races 1, 2, 3, and 4.