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Floret Development and Teliospore Production in Bunt-Infected Wheat, in Planta and in Cultured Spikelets. E. J. Trione, Agricultural Research Service, U.S. Department of Agriculture, Department of Crop Science, Oregon State University, Corvallis 97331; V. O. Stockwell(2), and C. J. Latham(3). (2)(3)Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 79:999-1002. Accepted for publication 18 May 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-999.

The formation of teliospores in the common and dwarf bunt-infected ovaries began when the spikes were about 65–70 mm long and the ovaries were 0.5 mm in diameter. In infected florets, the anthers developed abnormally, viable pollen was not produced, the filaments elongated only slightly, and anthesis did not occur. Infected ovaries were not fertilized, but they enlarged at a faster rate and achieved a larger size than the healthy ovaries. Greening of the infected ovaries was correlated with the onset of teliospore formation in the ovary, and as sporulation continued, the greening intensified. Healthy spikelets usually supported only two developing grains (the distal florets aborted), but 6–10 infected kernels were commonly produced per spikelet on dwarf-bunted plants. The possible involvement of hormones in the abnormal morphological alterations of the infected florets is discussed. Excised wheat spikelets infected with Tilletia controversa were successfully grown in liquid culture media containing sucrose, glutamine, salts, and minor organic factors. Varying the composition of the medium affected sporulation in the ovaries, and the highest sporulation occurred at 3 g L^–1 of glutamine.