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Morphological, Physiological, and Genetic Evidence in Support of a Conspecific Status for Tilletia caries, T. controversa, and T. foetida. Brian W. Russell, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331-2902; Dallice Mills, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331-2902. Phytopathology 84:576-582. Accepted for publication 21 February 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-576.

The germination properties and autofluorescence characteristics of teliospores of Tilletia spp. isolated from wheat grown in Oregon, Pakistan, and Turkey and electrophoretic karyotypes of monosporidial strains obtained from these teliospores were used as taxonomic characters in attempts to differentiate the teliospores that caused the bunt disease. Among the seven collections of teliospores were two that germinated at 16 C, a property of T. caries, but that had reticulations that autofluoresced under 485 nm UV irradiation, a characteristic of T. controversa. Other collections exhibited properties that suggested they could be one or the other species or T. foetida. The assignment of DNA fragments by hybridization to chromosomes resolved by pulsed-field gel electrophoresis revealed length polymorphisms that ranged from 8 to 11% for three chromosomes and 38% for the chromosome to which the rDNA genes map. The variability observed for the chromosomes of these diverse pathogen populations is not greater than that observed for homologous chromosomes of populations isolated from wheat grown in the western United States. Neither the autofluorescence nor the germination properties of teliospores could be used as definitive characters to distinguish these pathogens, and the karyotypes of strains from diverse populations are essentially identical for strains that cause both common and dwarf bunt of wheat.

Additional keywords: smut fungi, wheat bunt pathogens.