Scanning Microscopy


In plant pathology, low temperature preparation techniques now appear to be feasible methods to stabilize the dynamic ultrastructure of the host-(plant)-pathogen (fungi) interaction for an analysis by transmission electron microscopy. A well defined ultrastructure of small organisms (fungi) and large biological samples such as plant material and as well as the plant-pathogen (fungus) infection sites are presented. The mesophyll tissue of Arabidopsis thaliana is characterized by homogeneously structured cytoplasm closely attached to the cell wall. Infection sites of stem rust (Puccinia graminis f. sp. tritici) on primary leaves of wheat (Triticum aestivum) and powdery mildew (Erysiphe graminis f.sp. hordei) on coleoptiles of barley (Hordeum vulgare) are analyzed with regard to the fine structural preservation of the haustoria, the extrahaustorial matrix and the extrahaustorial membrane. Recent data on the immunocytochemical characterization of freeze substituted rust and powdery mildew infected plant tissue are described with special emphasis on the localization of elicitor glycoproteins involved in the cellular host-parasite interaction. There is clear evidence for the release of the elicitor glycoprotein into the extrahaustorial matrix of the haustorial complex. No elicitor molecules are seen in the plant host cytoplasm.

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