Use of Electron Microscopy to Characterize Teliospores of Tilletia caries and T. controversa. W. M. Hess, Professor, Department of Botany and Range Science, Brigham Young University, Provo, UT 84602. Edward J. Trione, Research Biochemist, USDA-ARS, Oregon State University, Corvallis 97331. Plant Dis. 70:458-460. Accepted for publication 28 October 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-458.

A specialized fixation procedure was used to distinguish morphological differences between teliospore walls of the wheat bunt fungi with transmission electron microscopy. The procedure consisted of hydration of spore sheaths, fixation in glutaraldehyde-acrolein, dehydration, critical-point drying, osmication, dehydration, critical-point drying, embedment in Spurr resin, and postsection staining with lead citrate. The sheaths of Tilletia controversa spores had a coarse, stippled appearance, whereas the sheaths of T. caries contained a fine network of parallel fibers. These characteristics of the wall were consistent and could be used to identify these species. Scanning electron microscopic procedures were also used for observing the outer layer of the spore wall, but they revealed inconsistent morphological differences that could not be used to identify these species.