Thiocarbamate Inhibition of Fatty Acid Biosynthesis in Isolated Spinach Chloroplasts

Abstract
EPTC (S-ethyl dipropylthiocarbamate) (33μM) and diallate [S-(2,3-dichloroallyl)diisopropylthiocarbamate] (90μM) inhibited the incorporation of 6 mM acetate-2-14C (Ac) by 80% and 65%, respectively, and the incorporation of 0.5μM malonate-2-14C (Mal) by 32% and 26%, respectively, into the lipids of spinach (Spinacia oleraceaL.) chloroplasts. The inhibition of Acor Malincorporation into lipids was not observed in the presence of excess Acor Mal, respectively. Incorporation of palmitate-1-14C and oleate-1-14C into chloroplast lipids was inhibited by EPTC and diallate. Malincorporation into dienoic fatty acids was inhibited by EPTC and diallate. The concentration of EPTC and diallate inhibiting lipid synthesis falls into the physiological range of these herbicides, explains some metabolic effects of these compounds, and fits as the mode of activity of these herbicides.