Herbicidal disruption of proton gradient development and maintenance by plasmalemma and tonoplast vesicles from oat root

Ratterman, Denise Marie; Balke, Nelson E.

doi:10.1016/0048-3575(88)90128-9

Cited by 21 publications

(24 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under these conditions, the activities of the enzymes would be maximal and not subject to effects of ApH formation on pump activity (22,27). ATPase activities for controls (Table IV) were consistent with those reported previously (25). ATPase activity was inhibited completely by 50 mM KNO3 (data not shown), an inhibitor of the tonoplast-type ATPase (33 (Table IV).…”

Section: Effect Of Dm and Vesicle Concentrationssupporting

confidence: 78%

“…This pH effect may be the basis for the apparent discrepancy between in vivo (36) and in vitro (25) relative activities of DM and DA. Wright and Shimabukuro (36) reported that DA caused a more rapid and more extensive depolarization of Ai, of oat coleoptile cells than DM did.…”

Section: Permeabilitymentioning

confidence: 99%

“…6). Because of this possibility, the stereospecificity of the disruption by DA of ATP-dependent ApH formation by plasmalemma and tonoplast vesicles (25) and of the depolarization by DA of cell membrane potentials (36) need to be determined.…”

Section: Permeabilitymentioning

confidence: 99%

“…K+-loaded vesicles (20)(21)(22)(23)(24)(25) Mug protein, 7.5 ML volume) were diluted into 1.5 mL of a K+-free medium (20 Quenching was reversed upon addition of a H+ ionophore (2.5 ,ug/mL gramicidin) or 10 mM NH4Cl (data not shown).…”

Section: Nonmetabolic Aphmentioning

confidence: 99%

See 3 more Smart Citations

Diclofop-Methyl Increases the Proton Permeability of Isolated Oat-Root Tonoplast

Ratterman¹,

Balke²

1989

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Diclofop-methyl (methyl ester of 2-[4-(2',4'-dichlorophenoxy)phenoxy]propionate; 100 micromolar) and diclofop (100 micromolar) inhibited both ATP-and PPi-dependent formation of H+ gradients by tonoplast vesicles isolated from oat (Avena sativa L., cv Dal) roots. Diclofop-methyl (1 micromolar) significantly reduced the steady-state H+ gradient generated in the presence of ATP. The ester (diclofop-methyl) was more inhibitory than the free acid (diclofop) at pH 7.4, but this relative activity was reversed at pH 5.7. Neither compound affected the rate of ATP or PPi hydrolysis by the proton-pumping enzymes. Diclofop-methyl (50, 100 micromolar), but not diclofop (100 micromolar), accelerated the decay of nonmetabolic H gradients established across vesicle membranes. Diclofop-methyl (100 micromolar) did not collapse K+ gradients across vesicle membranes. Both the (+)-and (-)-enantiomers of diclofop-methyl dissipated nonmetabolic H+ gradients established across vesicle membranes. Diclofopmethyl, but not diclofop (each 100 micromolar), accelerated the decay of H+ gradients imposed across liposomal membranes. These results show that diclofop-methyl causes a specific increase in the H permeability of tonoplast.The herbicide DM3 and its free acid form, DA, inhibit shoot and root growth and cause chlorosis and necrosis of oat and wild oat tissues (7,14,23,28). Ultrastructural damage observed in treated tissues includes breakdown of cellular membranes and destruction of cytoplasmic structure (5). Evidence indicates that they interfere with membrane-associated functions causing inhibition of mineral ion absorption (1), leakage of electrolytes from cells (7) cides is not known, presently two hypothetical mechanisms are being evaluated experimentally (10). In one model, the basis for structural and functional effects on cellular membranes is a direct interaction of the herbicide with the membrane or membrane components. A direct effect of DA on membrane function is indicated by the rapidity of depolarization of electrical potentials by DA (within 10 min [21,36]) and repolarization after removal of DA (40 s, with IAA addition [32]). The nature of the DA-membrane interaction or of the membrane components required for DA activity has not yet been determined. The second model suggests that membrane disruption is an indirect effect of herbicidal action resulting from an inhibition of the biosynthesis of membrane lipids. De novo fatty acid biosynthesis has been shown to be a sensitive site of action for DA (15,17). The I50 values for the inhibition by DA of ['4C]acetate incorporation by maize and oat chloroplasts were 0.2 and 0.1 M, respectively (15, 17). DA was more inhibitory than was DM (Iso = 10 uM) in these assays. Recent evidence indicates that the enzyme acetylCoA carboxylase is the site of inhibition by DA in this biosynthetic pathway ( 17).We have used an in vitro system of tonoplast vesicles isolated from oat root to study the possible direct action of DM and DA on membranes. With isolated membranes, effects of the h...

show abstract

Section: Effect Of Dm and Vesicle Concentrationssupporting

confidence: 78%

Section: Permeabilitymentioning

confidence: 99%

Section: Permeabilitymentioning

confidence: 99%

Section: Nonmetabolic Aphmentioning

confidence: 99%

See 2 more Smart Citations

Diclofop-Methyl Increases the Proton Permeability of Isolated Oat-Root Tonoplast

Ratterman¹,

Balke²

1989

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Also, it should be noted that the diclofop-induced depolarizations of Em seen in Figures 2A, 4A, and 5 do not reflect direct effects of diclofop on the plasmalemma H+ pump, but secondary effects either on the lipid bilayer or other ion transport systems. It has been demonstrated in studies with isolated membrane vesicles that diclofop has no direct effect on either the plasmalemma or tonoplast H+ pumps (19,20).…”

Section: Discussionmentioning

confidence: 99%

Effects of Diclofop and Diclofop-Methyl on Membrane Potentials in Roots of Intact Oat, Maize, and Pea Seedlings

DiTomaso¹,

Brown²,

Stowe³

et al. 1991

Plant Physiol.

View full text Add to dashboard Cite

Growth and electrophysiological studies in roots of intact diclofop-methyl susceptible and resistant seedlings were conducted to test the hypothesis that the herbicide acts primarily as a proton ionophore. The ester formulafton of diclofop, at 0.2 micromolar, completely inhibited root growth in herbicide-susceptible oat (Avena Lucas et al. (16) and later revised by Wright and Shimabukuro (25), the ester form of diclofop crosses the plasmalemma and is rapidly hydrolyzed to the free acid form. This undissociated acid then releases a proton on the cytoplasmic side of the membrane. The deprotonated anionic species then moves back across the plasmalemma to the apoplasmic side in response to the root-cell Em (inside negative) and is again protonated. This cycle is repeated until the proton gradient is dissipated and could eventually lead to a reduction in cellular ATP levels by short circuiting the proton-translocating plasmalemma ATPase. The diclofop concentration causing half-maximal depolarization of the Em in excised and peeled oat coleoptiles was determined to be 10 to 20 jtM (25). Ratterman and Balke (20)

show abstract

The herbicide flamprop‐M‐methyl has a new antimicrotubule mechanism of action

Tresch¹,

Niggeweg²,

Großmann³

2008

Pest Management Science

View full text Add to dashboard Cite

show abstract

Herbicidal disruption of proton gradient development and maintenance by plasmalemma and tonoplast vesicles from oat root

Cited by 21 publications

References 33 publications

Diclofop-Methyl Increases the Proton Permeability of Isolated Oat-Root Tonoplast

Diclofop-Methyl Increases the Proton Permeability of Isolated Oat-Root Tonoplast

Effects of Diclofop and Diclofop-Methyl on Membrane Potentials in Roots of Intact Oat, Maize, and Pea Seedlings

The herbicide flamprop‐M‐methyl has a new antimicrotubule mechanism of action

Contact Info

Product

Resources

About