Abstract
Chemotactic response of zoospores of two mangrove strains of Halophytophthora vesicula (isolates LEM-031 and LEM-036) was evaluated using a capillary root model for chemotaxis assay. Different compounds were tested as attractants, including amino acids, carbohydrates, lectins, ethanol and plant material and extracts. Zoospores of the two strains were found to be chemotactically attracted to all the plant material and extracts tested. Among amino acids, glutamic acid elicited strong chemotactic activity on zoopores of both strains while asparagine on zoopores of isolate LEM-031 only. Ethanol and the polysaccharide pectin also induced a strong chemotactic response on zoospores of both strains. True chemotaxis of zoospores was observed among substances which elicited positive chemotactic response, except for glutamic acid which resulted in are-attraction response on zoospores. Trapping of accumulated zoospores was observed in pectin, ethanol, glucose, fructose and glutamic acid which resulted in encystment and subsequent germination. A negative chemotactic response was observed in lectins and the amino acids arginine, methionine and histidine, for both strains.