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Selection and Culture of Auxotrophic and Drug-Resistant Mutants of Tilletia caries. A. C. L. Churchill, Former graduate research assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331, Present address: Plant Pathology Laboratory, Plant Protection Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705; Dallice Mills, associate professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 74:354-357. Accepted for publication 25 October 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-354.

Mutagenesis and selection procedures for isolation of auxotrophic mutants of Tilletia caries race T-1 were developed. Mutants with requirements for adenine, uracil, glycine, or a general nitrogen source were identified. Only spontaneous mutation to cycloheximide resistance was observed in tests with 12 growth-inhibiting drugs. These latter mutants had restricted colony growth and generally failed to produce secondary sporidia in the presence of cycloheximide. Paired, sexually compatible, auxotrophic, haploid strains produced mycelial growth on minimal medium, presumably because of heterokaryosis. Secondary sporidia derived from these matings exhibited the nutrient requirement of either parent, indicating that the frequency of reverse mutation and stable diploid formation was low.

Additional keywords: common bunt, complementation, smut.