Adhesion of Phytophthora palmivora zoospores: detection and ultrastructural visualization of concanavalin A-receptor sites appearing during encystment.

The binding of concanavalin A (Con A) to the cell surface of zoospores and cysts of Phytophthora palmivora was studied by radiometry (125I-Con A), ultraviolet microscopy (fluorescein-Con A) and electron microscopy peroxidase-diaminobenzidine technique). Zoospores were found to secrete during the early stages of encystment a Con A-binding material susceptible to trypsin digestion. This glycoprotein is contained in the so-called peripheral vesicles and is probably responsible for the adhesion of the encysting zoospores to solid surfaces.