Effects of 2,4-D and Other Herbicides on Oxidative Phosphorylation in Mitochondria from Cabbage

Abstract

The effects of 22 herbicides on oxidative phosphorylation in mitochondria from cabbage (Brassica oleracea var. capitata L.) have been studied. Carbamates, phenoxyacids, 3,5-dimethyltetrahydro-l,3,5,2H-thiadiazine-2-thione (DMTT), N-1-napthylphthalamic acid (NPA), 2,3,6-trichlorobenzoic acid (2,3,6-TBA), 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), and 2-chloro-2-N,N-diallylacetamide (CDAA) inhibited phosphorylation to a greater extent than oxygen uptake in cabbage mitochondria. The compounds 1,2-dihydropyridazine-3,6-dione (MH), 2,2-dichloropropionic acid (dalapon), 2,2,3-trichloropropionic acid (hereinafter referred to as 2,2,3-TPA), sodium chlorate, and 3-amino-l,2,4-triazole (amitrole) at concentrations as high as 1 × 10–2 M did not have a large effect on oxidative phosphorylation in cabbage mitochondria. Respiration which was stimulated by 2,4-dinitrophenol (DNP) or adenosine diphosphate (ADP) was inhibited by 2,4-dichlorophenoxyacetic acid (2,4-D). Although 2,4-D did not affect Mg++-stimulated adenosine triphosphatase (ATPase), it inhibited an oleate-stimulated ATPase activity and the ATP-32Pi exchange reaction in cabbage mitochondria. The results suggest that 2,4-D may inhibit respiration in cabbage mitochondria by an effect on a reaction involved in coupling phosphorylation with electron transport.

The INHIBITION OF GIBBERELLIC ACID INDUCTION OF Α‐AMYLASE ACTIVITY IN BARLEY ENDOSPERM BY CERTAIN HERBICIDES

“…Not only is ATP necessary for protein synthesis but it is also required for the RNA synthesis that precedes protein synthesis. Lotlikar et al (1968) found that chlorpropham effectively inhibited oxidative phosphorylation in cabbage mitochondria, inhibition being over 90% at 10"^ M. Dichlobenil at 1-45 x 10~* M inhibits ATP formation in isolated cucumber mitochondria by about 59% (Foy & Penner, 1965).…”

“…Since one of the functions of GA in the germinating barley seed is to induce the de novo synthesis of a-amylase (Filner & Varner, 1967), it is not surprising that amylolytic activity in the barley endosperm test is reduced by dichlobenil and chlorpropham. Both herbicides have been shown to uncouple phosphorylation from electron transport (Lotlikar, Remmert & Freed, 1968;Foy & Penner, 1965), an activity that deprives growing plant tissues (such as a germinating seed) ofa readily-available supply of ATP. Not only is ATP necessary for protein synthesis but it is also required for the RNA synthesis that precedes protein synthesis.…”

The Effect of Simazine on the Growth and Respiration of a Cell Suspension Culture of Celery

“…In the intact plants of Elodea (Roth, 1958) and Seeale eereale (Ries et al, 1967) respiration was stimulated but in Convolvulus arvensis (Chodova and Zemanek, 1971) it was inhibited. With intact isolated mitochondria, Lotlikar, Remmert and Freed (1968) found a stimulation of respiration suggesting that simazine was acting as an uncoupler, although it had no effect on yeast mitochondria (Hachimori, Nosoh and Sone, 1968).…”

The Mode of Action of Foliage‐applied Translocated Herbicides With Particular Reference to the Phenoxy‐acid Compounds

“…5 x 10"^ M), MCPA and MCPB were equally effective . Lotlikar (1960), using cabbage {Brassica oleracea L.) mitochondria, reported that 2,4-D and 4-(2,4-DB) inhibited phosphorylation to a greater degree than respiration and several authors have reported the activity of phenoxy-acid compounds as uncouplers or inhibitors of oxidation (see section on Effects on respiratory metabolism).…”

“…There is evidence that oxidative phosphorylation is influenced both by phenoxyacetic and phenoxybutyric compounds. Lotlikar (1960) reported that 2,4-D and 4-(2,4-DB) have a greater inhibitory eflect on phosphorylation than on respiration of cabbage mitochondria. Smith & Shennan (1966) found that 5 x 10"^ M MCPB completely inhibited endogenous respiration, whereas maximum inhibition by a similar concentration of MCPA was 52%.…”