Abstract
Zoospores of Aphanomyces raphani Kendrick accumulate to hypocotyl of cabbage seedling near the soil surface of the artificially infested soil.
When the seedling was dipped in the eosin solution, a special cell or special group of cells on the hypocotyl was stained. Similar result was also obtained with ninhydrin reaction. Zoospores have a tendency to accumulate on the areas stained with eosin.
Zoospores were strongly attracted by crude exudates from hypocotyls of cabbage seedlings, and the exudates were separated into basic, acid, and neutral fractions with Dowex ion exchange resins. When capillary holding each fraction was put in zoospore suspension, the basic one attracted zoospores most effectively and its activity was found to be equivalent to that of crude exudates. Sixteen amino acids which were detected in basic fraction and other two amino acids did not attract zoospores effectively.
