Vogler, D. R., Cobb, F. W., Jr., and Epstein, L. 1989.
Department of Plant Pathology, University of California, Berkeley 94720.
Phytopathology 79:1164. (1989)
We used epifluorescent microscopy to count nuclei in aeciospores from two zymodemes (electrophoretic types) of Peridermium harknessii J. P. Moore. For each single-gall isolate, spores were fixed overnight at 4C in 3.7% formaldehyde, pelleted by centrifugation, resuspended in 0.1 microgram/ml 4,6-diamidino-2- phenylindole (DAPI) for 6 min, pelleted and rinsed with water 6 times, and mounted in 75% glycerol in 25% phosphate buffer (pH 8). Nuclei were counted at 800X using filters recommended for DAPI by the microscope manufacturer (Zeiss). Spores from zymodeme I (collected from several pine hosts throughout California) were predominantly (>75%) binucleate, while spores from zymodeme II (collected from lodgepole pine in the central Sierra Nevada) were predominantly uninucleate. Implications for the nuclear behavior of this endemic forest pathogen are discussed.