Structural Changes at the Plant-Fungal Interface

Cytological studies, because of the spatial and temporal information they provide, are of great importance in understanding plant-fungal interactions. With fungal plant parasites, some structural changes at the plant-fungal interface result from the direct action of fungal enzymes or toxins. Others are the result of plant responses to the presence of the fungus. Some of the latter, such as compositional modifications of cell walls, appear to be part of the repertoire of responses to stress that a plant possesses. Others, such as the cellular changes accompanying intracellular haustorium formation by biotrophic parasites, seem to be induced by the fungus to provide an environment favorable for successful infection. In general, the most informative studies involve the use of cytochemical stains and procedures to investigate compositional and functional changes in cell walls and cell membranes. More difficult to interpret are descriptive investigations of fungal-induced changes in internal cell ultrastructure. Further progress will require integration of cytological studies with other methods of investigation. In such future multidisciplinary investigations, cytological studies could play at least three major roles: (1) to provide spatial and temporal descriptive information of the specific plant-fungal interaction, (2) to locate specific molecules in time and space, and (3) to facilitate rapid and multicomponent bioassays of experimental treatments