Ultrastructural analysis of the behavior of the dimorphic fungus Microbotryum violaceum in fungus-induced anthers of female Silene latifolia flowers |
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Authors: | Wakana Uchida Sachihiro Matsunaga Shigeyuki Kawano |
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Institution: | (1) Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba;(2) Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka |
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Abstract: | Summary. The development of male organs is induced in female flowers of the dioecious plant Silene latifolia by infection with the fungus Microbotryum violaceum. Stamens in a healthy female flower grow only to stage 6, whereas those in an infected female flower develop to the mature
stage (stage 12), at which the stamens are filled with fungal teliospores instead of pollen grains. To investigate these host–parasite
interactions, young floral buds and fungus-induced anthers of infected female flowers were examined by electron microscopy
following fixation by a high-pressure freezing method. Using this approach, we found that parasitic hyphae of this fungus
contain several extracellular vesicles and have a consistent appearance up to stage 8. At that stage, parasitic hyphae are
observed adjacent to dying sporogenous cells in the infected female anther. At stage 9, an increased number of dead and dying
sporogenous cells is observed, among which the sporogenous hyphae of the fungus develop and form initial teliospores. Several
types of electron-dense material are present in proximity to some fungi at this stage. The initial teliospores contain two
types of vacuoles, and the fungus cell wall contains abundant carbohydrate, as revealed by silver protein staining. The sporogenous
cell is probably sensitive to infection by the fungus, resulting in disruption. In addition, the fungus accelerates cell death
in the anther and utilizes constituents of the dead host cell to form the mature teliospore.
Correspondence and reprints (present address): Molecular Membrane Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako, Saitama
351-0198, Japan. |
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Keywords: | : Anther Microbotryum violaceum Parasitism Silene latifolia Teliospore |
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