VIEW ARTICLE

Techniques

New Tests to Distinguish Teliospores of Tilletia controversa, the Dwarf Bunt Fungus, from Spores of Other Tilletia species. E. J. Trione, Research Biochemist, Agricultural Research Service, U.S. Department of Agriculture, Oregon State University, Corvallis, OR 97331 ; B. B. Krygier, Biological Laboratory Technician, Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331. Phytopathology 67:1166-1172. Accepted for publication 18 March 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1166.

The transport of spores of Tilletia controversa on wheat shipments from one country to another is of international concern. By either light- or scanning electron microscopy, the morphological features of teliospores of various bunt and smut fungi are similar; thus, new distinctive identification tests were needed. Dry spores of T. controversa were shown to be spherical and normal in appearance in anhydrous propanol, whereas dry spores responsible for common bunt and grass smut were aspherical and deformed. A negative staining reaction (spores stained with methylene blue then mixed with India Ink) clearly showed the capsule on spores of smut fungi and aided identification. If the spores germinate in 1 wk on 3% water agar at 17 C, they are not spores of T. controversa. Spores of smut fungi first partially hydrolyzed with cellulase and then with protease showed a differential agglutination reaction with the lectin phytohemagglutinin-M, as well as with 4 M NaCl and 0.06 M MgCl₂; spores of T. controversa agglutinated strongly, whereas those of the common bunt fungus gave a weak agglutination reaction. A periodate oxidation reaction (0.16 M H₅IO₆, 0.1 M sodium acetate at pH 4.5, 57 C for 3.25 hr) removed the reticulum more readily from the outer wall of spores of common and grass smut fungi than from spores of the dwarf bunt fungus. The anhydrous propanol and the negative staining tests are recommended for routine use in identifying spores of smut fungi.