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Resistance

Genetic Control of Disease Expression in Stem Rust of Wheat. W. Q. Loegering, Professor emeritus, University of Missouri, Agricultural Research, SEA, USDA, Columbia, MO 65211; E. R. Sears, geneticist, Agricultural Research, SEA, USDA, Columbia, MO 65211. Phytopathology 71:425-428. Accepted for publication 9 June 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-425.

In stem rust of wheat, susceptibility as measured by infection type may be genetically determined by the genotype of either the host or the pathogen. The absence of a locus, due to aneuploidy, is the equivalent of an allele for susceptibility. Thus, it may be assumed that in the euploid the allele for susceptibility may be either a nonfunctional DNA sequence or, if functional, the gene product does not interact with the gene product of the corresponding definitive gene in the host. It was also confirmed that in some cases high temperature may change a definitive phenotype to nondefinitive.