SURFACE-RELATED CHANGES OF FUSING PHYTOPHTHORA ZOOSPORES

Zoospores of Phytophthora spp. were fused and then regenerated using a technique previously described. At various points in the fusion and r egeneration processes, components of spore surfaces were immunolabelle d with specific monoclonal antibodies. Changes in the antigenic proper ties of spore surfaces during these events were monitored by fluoresce nce microscopy. Additional, surface-related processes of the phenomena were monitored by electron microscopy. In the presence of lithium ion s and polyethylene glycol, zoospores aggregated into clumps and began to fuse. During this time, zoospores retained their reniform shape and antibodies reacted only with plasma membrane-bound antigenic componen ts that are characteristic of the zoospores state. Immunolabelling of cell wall occurred only after the fusion solution was replaced with a regeneration solution. As expected, the fusion and the asynchronous re generation process resulted in the formation of enlarged cells with en larged or multiple nuclei.