Lipid Metabolism as a Site of Herbicide Action

Abstract

Dinoseb (2-sec-butyl-4,6-dinitrophenol) and MBR 8251 [1,1 1-trifluoro-4′-(phenylsulfonyl)-methanesulfono-o-toluidide] inhibited enzymic synthesis of glycerides in vitro. The physiological significance of this inhibition was confirmed in intact wheat [Triticum aestivumL., ‘Mediterranean’ (C.I. 5303)] seedlings; dinoseb and MBR 8251 inhibition of glyceride synthesis in vivo was evidenced by a buildup in free fatty acids and a decrease in neutral and polar lipids. Glyceride synthesis and growth were reduced approximately equally by dinoseb and MBR 8251. However, polar (membrane) lipids were reduced more drastically than growth. It is suggested that dinoseb and MBR 8251 alter membrane structure and function through an inhibition of membrane lipid synthesis. DNP (dinitrophenol) was only slightly inhibitory in either the in vitro or in vivo system. Dinoseb was more effective than MBR 8251 in destruction of cell membrane permeability of intact roots immediately after treatment.