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Ultrastructure of the Infection of Poinsettia by Oidium SP. using High Pressure Freezing and Freeze Substitution

Published online by Cambridge University Press:  02 July 2020

G. J. Celio
Affiliation:
Department of Plant Pathology, University of Georgia, Athens, GA30602
E. A. Richardson
Affiliation:
Department of Botany, University of Georgia, Athens, GA30602
C. W. Mims
Affiliation:
Department of Plant Pathology, University of Georgia, Athens, GA30602
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Extract

Cryofixation is becoming more widely used to study host-pathogen relationships in fungal diseases of plants. This presentation describes results we have obtained using high pressure freezing and freeze substitution to study powdery mildew disease of poinsettia ﹛Euphorbia pulcherrima) caused by Oidium sp.

Approximately 0.5 mm leaf disks bearing sporulating colonies of Oidium sp. were excised and placed in a 15% dextran solution contained in brass planchets. Samples were frozen using a Balzer's HPM 010 High Pressure Freezing Machine and substituted according to the procedures of Hoch.6 Thin sections of embedded leaves were cut using a diamond knife, collected on gold slot grids, and placed on formvar-coated racks. Sections were poststained with uranyl acetate and lead citrate and examined using a Zeiss EM 902A transmission electron microscope.

Outstanding preservation of haustoria, the specialized nutrient-absorbing structures produced in host epidermal cells by Oidium, was obtained. Both young, unlobed (Fig. 1) as well as mature, highly lobed (Fig. 2) haustoria were observed.

Type
Light and Electron Microscopic Techniques for the Study of Plant Pathogenic Fungi and Their Interactions with Host Plants
Copyright
Copyright © Microscopy Society of America

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References

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7. This research was supported by NIH Grant #5T32AI07373, Pre-Doctoral Training in Molecular and Cellular Mycology.Google Scholar