Activity of Host-derived Attractants and Their Related Compounds toward the Zoospores of Phytopathogenic Aphanomyces cochlioides

Abstract

Eleven flavones, including cochliophilin A and a chromone, were chemically prepared to determine the attracting activity for zoospores of Aphanomyces cochlioides, a causative fungus of spinach root rot. Analyses of the structure-activity relationship of each revealed a significant correlation between the zoospore attracting activity and the A-ring oxygenation at C-5 and C-7 in the flavone skeleton. The relative attractancy of four regio-isomers of Ntrans-feruloyl 4-O-methyldopamine, which was identitied as a zoospore attractant specific to another host plant Chenopodium album, was also examined.