Staining methods for the investigation of Plasmopara viticola and its infection structures in semi-thin sections

The investigation of Plasmopara viticola, that spends most of its life cycle inside of leaves, requires specific staining techniques. It is desirable to visualize both, host cells and parasitic structures, given their silimar chemical constitutions, especially in reference to the cell wall. On the basis of appropriate staining procedures it was possible to demonstrate parasitic structures during the infection process. Several dyes and optical brighteners were successfully used to identify hyphae, vesicles, haustoria, gametangia and oospores. The chemical determination of the stained structures is discussed.