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Cytology and Histology

The Ultrastructure and Nuclear DNA Content of Tilletia indica. C. D. Therrien, Associate professor, Departments of Biology and Plant Pathology, The Pennsylvania State University, University Park 16802; M. H. Royer(2), and J. A. Strauss(3). (2)Research plant pathologist, Foreign Disease-Weed Science Research Unit, USDA-ARS, Ft. Detrick, Building 1301, Frederick, MD 21701; (3)Graduate assistant, Department of Biology, The Pennsylvania State University. Phytopathology 78:728-732. Accepted for publication 10 December 1987. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1988. DOI: 10.1094/Phyto-78-728.

The cytology of Tilletia indica, the incitant of Karnal or partial bunt of wheat, was investigated by transmission electron microscopy (TEM) and Feulgen-DNA (F-DNA) cytophotometry. Numerous mitoses followed meiosis in the teliospores, which were multinucleate when they germinated. The mean F-DNA content of the filiform primary sporidia was 0.115 arbitrary units (a.u.), that of the allantoid secondary sporidia 0.175 a.u. The mean F-DNA content of nuclei of binucleate teliospore initials was 0.217 a.u., that of postfusion nuclei 0.473 a.u. Apparently DNA replication in the teliospore initials occurred before nuclear fusion. Ultrastructural investigations of the teliospore initials showed that, whereas fusion nuclei were initially binucleolate, as teliospores developed they became uninucleolate.