ACTIVITY OF HOST-DERIVED ATTRACTANTS AND THEIR RELATED-COMPOUNDS TOWARD THE ZOOSPORES OF PHYTOPATHOGENIC APHANOMYCES COCHLIOIDES

Eleven flavones, including cochliophilin A and a chromone, were chemic ally prepared to determine the attracting activity for zoospores of Ap hanomyces cochlioides, a causative fungus of spinach root rot, Analyse s of the structure-activity relationship of each revealed a significan t correlation between the zoospore attracting activity and the A-ring oxygenation at C-5 and C-7 in the flavone skeleton, The relative attra ctancy of four regio-isomers of N-trans-feruloyl 4-O-methyldopamine, w hich was identified as a zoospore attractant specific to another host plant Chenopodium album, was also examined.