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

Abstract

Summary. The influence of the four herbicides 2,6‐dichlorobenzonitrile (dichlobenil), isopropyl‐N‐(3‐chlorophenyl)carbamate (chlorpropham), 2‐chloro‐N‐isopropylacetani‐lide (propachlor) and 2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl)acetanilide (alachlor) on GA induction of a‐amylase in the barley endosperm test was studied. Amylase induction by GA was inhibited by all four herbicides, dichlobenil and chlorpropham being more active in this respect. In all cases, inhibition increased with the addition of increasing concentrations of herbicide. Addition of the herbicides to the reaction mixture showed that none of them directly affected the enzyme—starch reaction. Inhibition de V induction par l'acide gibbirellique de activité de α‐amylase dans l’endosperne de I'orge, sous faction de certains herbicides Résumé. Les auteurs ont étudié l'influence de 4 herbicides, le 2,6‐dichlorobenzonitrile (dichlobénil), le. N‐(3‐chlorophényle) carbamate d'isopropyle (chlorpropham), la 2‐chloro‐N‐iso‐propylacétanilide (propachlore) et la 2‐chloro‐2′,6′‐diéthyl‐N‐(méthoxy‐méthyle) acétanilide (alachlore), sur l'induction par l'acide gibbérellique de l'α‐amylase dans l'endosperme de I'orge. L'induction de l'amylase par l'acide gibbérellique fut inhibée par les quatre herbicides, le dichlobénil et le chlorpropham se montrant les plus actifs à cet égard. Dans tous les cas, l'inhibition s'accrut avec I'addition de concentrations croissantes d'herbicide. L'addition des herbicides au mélange en réaction montra qu'aucun d'entre eux n'affectait directement la réaction enzymatique de l'amidon. Die Hemmung der gibberellininduzierten α‐Amylaseaktimtdt in Gerstenendosperm durch gewisse Herbizide Zusammenfassung. Der Einfluss der vier Herbizide 2,6‐Dichlorbenzonitril (Dichlobenil), Isopropyl‐N‐(3‐chlorphenyl)‐carbamat (Chlorpropham), 2‐Chlor‐N‐isopropylace‐tanilid (Propachlor) und2‐Chlor‐2′,6′‐diäthyl‐N‐(methoxymethyl)‐acetanilid (Alachlor) auf die gibberellininduzierte α‐Amylasebildung in Gerstenendosperm wurde untersucht. Die Induktion von α‐Amylase durch Gibberellinsäure wurde von alien vier Herbiziden ge‐hemmt. Am wirksamsten waren hierbei Dichlobenil und Ghlorpropham. In alien Fällen wurde die Hemmwirkung durch ansteigende Herbizidkonzentrationen verstärkt. Die Zugabe der Herbizide zu dem Reaktionsgemisch zeigte, dass keines von ihnen die Reaktion zwischen Enzym und Stärke direkt beeinflusste.

Contraction of chromosomes and depression of RNA synthesis by isopropyl N-(3-chlorophenyl) carbamate (CIPC) in Vicia faba root tip cells.

“…On the other hand, the production of amylase in GA-treated non-dividing aleurone cells of barley is also inhibited by these herbicides (Yung andMann 1967, Devlin andCunningham 1970). The hypothesis proposed by Mann et al (1967) was to suggest the physiological probability of inhibition of RNA synthesis in the nucleus by carbamate herbicides, perhaps connecting with the observed effects on chromosome contraction.…”

Metolachlor and Alachlor Effects on Membrane Permeability and Lipid Synthesis

“…Numerous studies have been conducted to determine the mechanism of action of the a -chloroacetamides. Studies of photosynthesis (3,16), respiration (9,16,19), a-amylase synthesis (5,15,18,23), RNA synthesis (15), protein syn thesis (7,12,15), and lipid synthesis (6,23,24) have failed, however, to elucidate the primary mechanism of action.…”

“…Although studies with certain a-chloroacetamides suggest they are inhibitors of protein synthesis (7,12,15), Pillai et al (17) found that, with metolachlor, leucine incorporation into protein was inhibited only at concentrations of 1 X 10" 4 M and higher. Inhibition of a-amylase synthesis in de-embryonated barley (Hordeum vulgare L.) seed by CDAA (N,Ndiallyl -2 -chloroacetamide) (15) and alachlor (5,18) has been reported. Using seed completely freed of contaminating microorganisms, however, Diner 3 found that a-amylase synthesis in de-embryonated 'Himalaya' barley was inhibited by alachlor and metolachlor only at concentrations in excess of 1 X 10' 3 M.…”

Influence of Alachlor and Two Experimental Herbicides on Bud Break, Terminal Growth and Root Development of Cranberry Cuttings

“…The sites most sensitive to the inhibition of protein synthesis by propachlor appear to be the root meristematic zones. Also, Devlin & Cunningham (1970) found that both propachlor and alachlor inhibited GA induction of a-amylase activity in barley endosperm, a finding that suggests an adverse influence of the acetanilides on protein synthesis. This may be why all treatments with alachlor completely inhibited root development in cranberry cuttings.…”