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Ultrastructure of Ornamentation Development on Aeciospores of Cronartium quercuum Forma Specialis Fusiforme
Charles W. Mims and Robert W. Roberson
Vol. 75, No. 3 (May - Jun., 1983), pp. 400-411
Published by: Mycological Society of America
Stable URL: http://www.jstor.org/stable/3792682
Page Count: 12
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Mature aeciospores of Cronartium quercuum f. sp. fusiforme are incompletely verrucose. While most of the spore surface is covered with annulated, wart-like verrucae, each spore also possesses a smooth region that runs the length of the spore and extends around each end. This study suggests that the verrucae and the smooth portion of the spore ornamentation are composed of the same type of material. Verrucae initially appear as small, electron-transparent structures near the outer surface of the plasma membrane just beneath the primary aeciospore wall. Many vesicles are associated with developing verrucae, but not with the developing smooth portion of the ornamentation. The smooth portion of the ornamentation forms as a result of the lateral fusion of small electron-transparent structures that initially resemble very young verrucae. Cisternae of ER characteristically lie just beneath both developing verrucae and the smooth portion of the ornamentation. The verrucae and smooth portion of the ornamentation are exposed on the spore surface following the disintegration of the primary aeciospore wall. A secondary wall eventually forms between the ornamentation and the spore plasma membrane. A shroud-like layer of electron-opaque material is present on the surface of a mature spore.
Mycologia © 1983 Mycological Society of America