Inheritance of Resistance to Pathotypes 1, 2, and 3 of Peronosclerospora sorghi in Sorghum. Jose Sifuentes, Graduate Research Assistant, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, College Station 77843. R. A. Frederiksen, Professor, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, College Station 77843. Plant Dis. 72:332-333. Accepted for publication 30 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0332.

The relationship between the genes for resistance to Peronosclerospora sorghi pathotypes 1, 2, and 3 in the sorghum lines QL3-India and SC414-12 were investigated by making reciprocal crosses between them and susceptible lines. The results supported the hypothesis that QL3-India has two genes conditioning resistance to each of the three pathotypes, whereas SC414-12 has one gene for resistance to the same three pathotypes. There appears to be no linkage between those genes, since the observed segregation in the F₂ of the cross between the resistant parents was in agreement with a 63:1 ratio. Management of these three genes to prolong the life of sorghum cultivars is advocated.