Regulation of Lipid Synthesis in Soybeans by Two Benzoic Acid Herbicides

Abstract

The effects of 3-nitro-2,5-dichlorobenzoic acid (dinoben) and 3-amino-2,4-dlchlorobenzolc acid (chloramben) on lipid formation and on the incorporation of various substrates into lipids by intact seeds and subceflular fractions of germinating soybean (Glycine max [L.] Merr.'Amsoy') were studied. Dinoben (20 lg/ml) inhibited synthesis of total lipils 67%, neutral lipids 73%, glycolpids 51%, and pbospholipids 39% in germinating seeds. When polar lipids were analyzed further, inhibition of individel lipid dcass was also observed. Chloramben (20 pg/ml) stimulated total lpid synthesis 25%. With the exception of the mitochondrial fraction where malonate thiokinase was absent, dinoben inhibited up to 99% the incorporation of acetate and malonate into lpids, but did not inhibit acetyl-CoA and malonyl-CoA incorporation.Chloramben stimulated the incorporation of aU substrates tested into lipids by all fractions except the mitochodrial fraction when malonate was the substrate. When dinoben and chloramben were used in combinations, chioramben did not reverse the inhibitory effect of dinoben.It is concluded that the dinoben inhibitory effect specific and is assodated with the acetate and malonate thiokinase systems. The chioramben effect b stimulatory to either acetyl-CoA carboxylase or fatty add synthetase or both.Recently, research on various aspects of soybean metabolism has increased substantially. However, little is known about specific metabolic processes in soybean during germination. In particular, lipid synthesis during germination of soybean has not been studied in great detail.Quantitative and qualitative alteration of membrane lipid composition results in changes in chloroplast and mitochondrial functions and membrane permeability capacity (1, 9). Thus, chemical inhibition of lipid synthesis could ultimately result in loss of photosynthetic and respiratory activity, plant necrosis, and changes in the nutritional balance of seedlings. Mann [L.] Merr. 'Amsoy') were germinated at 25 C in small test tubes (one seed/tube) in 0.5 ml of deionized H20 containing 0.25 ,uCi of 1-14C-acetate and the proper concentration of chloramben or dinoben. After 24 hr (unless otherwise indicated), the germinated seeds were transferred to 95 C deionized H20 for 2 min and then washed three times with 100 ml of water.

Morphological and cytological studies on Arceuthobium (Viscaceae) in relationship to host phloem with studies on the healthy phloem in Pinus sabiniana (Pinaceae)

“…Another herbicide that should be investigated for a possible selective killing action against Arceuthobiwn is a benzoic acid herbicide called dinoben. Its potential usefulness lies with the fact that it is a selective herbicide which inhibits fatty acid 105 and lipid synthesis in fat-storing plants (Muslih and Linscott, 1977). It is possible that selective inhibition of Arceuthobium sinker cell metabolism can be achieved with this herbicide, despite the close physical relationship of endophytic cells with host vascular tissue.…”