抄録
Plant pathogenic Phycomycetes produce zoospores which can move in soil water toward the host plants. The zoospores of Aphanomyces cochlioides a causal fungus of the spinach root rot, are attracted to chemotropic stimulants in the host roots and root exudates. Cochliophlin A, 5-hydroxy-6, 7-methylenedioxyflavone was identified as one of host specific attractants from the root exudates. The zoospores are attracted topically at some parts of the root surfaces. To visualize the behavior of zoospores, we took microphotographs and recorded on video tapes. The zoospores attracted to drops of fluorocarbon FC-72 solution of cochliophlin A in water aggregated topically on the surface as well as that of host roots. The result of visualization suggested that the topical aggregation on the surfaces of spinach root or the FC-72 solution of cochliophilin A was guided by cochliophilin A and an additional factor like an aggregation pheromone.
