INTERFERENCE OF FLURIDONE WITH THE DESATURATION OF PHYTOENE BY MEMBRANES OF THE CYANOBACTERIUM APHANOCAPSA

The effect of the bleaching herbicide fluridone was investigated by in vivo and in vitro studies using the cyanobacterium Aphanocapsa. After application, all colored carotenoids and chlorophyll decreased, and phytoene was accumulated in the cells. Direct inhibition of phytoene desaturation was demonstrated with a membrane preparation that converts geranylgeranyl pyrophosphate into phytoene and further to β-carotene. A double-reciprocal plot of phytoene conversion into β-carotene in the presence of fluridone and binding studies with radioactive labeled fluridone showed that this herbicide is a reversible noncompetitive inhibitor of phytoene desaturase. © 1992.