VIEW ARTICLE

Genetics

Inheritance of Resistance in Soybeans to Physiologic Races 5, 6, 7, 8, and 9 of Phytophthora megasperma var. sojae. F. A. Laviolette, Associate professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; K. L. Athow(2), E. H. Mueller(3), and J. R. Wilcox(4). (2)(3)Professor, and graduate research assistant, respectively, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; (4)Professor, Department of Agronomy, Purdue University, West Lafayette, IN 47907, and Research Geneticist, Federal Research, Science and Education Administration, U.S. Department of Agriculture (FRSEA, USDA). Phytopathology 69:270-271. Accepted for publication 25 September 1978. 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, 1979. DOI: 10.1094/Phyto-69-270.

The F₂ populations from nine soybean crosses were tested with physiologic races 5, 6, 7, 8, and 9 of Phytophthora megasperma var. sojae. The gene Rps^a in the soybean cultivar Mukden, which gives resistance to races 1 and 2 and susceptibility to races 3 and 4, gave susceptibility to races 5, 6, 7, 8, and 9. The gene Rps^b, which conditions resistance to races 1, 3, and 4 but susceptibility to race 2 in PI 84637, gave resistance to races 5, 6, 7, 8, and 9. The gene Rps^c in PI 54615-1, which gives resistance to races 1, 2, and 3 and susceptibility to race 4, gave susceptibility to race 5 and resistance to races 6, 7, 8, and 9. These three genes are located at the same locus. The independent gene Rps3 in PI 86972-1, which conditions resistance to races 1, 2, 3, and 4, gave resistance to races 5, 8, and 9 but susceptibility to races 6 and 7. Lines with the genotypes Rps^b Rps^b Rps3 Rps3 and Rps^c Rps^c Rps3 Rps3 have been selected which are resistant to the nine reported physiologic races of the fungus.