Are Redox Reactions Involved in Regulation of K+ Channels in the Plasma Membrane of Limnobium stoloniferum Root Hairs?

Grabov, Alexander; Böttger, Michael

doi:10.1104/pp.105.3.927

Cited by 31 publications

(16 citation statements)

References 22 publications

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“…(Grabov and B6ttger 1994). Our results would be consistent with e-acceptors causing membrane depolarization and then decreasing K + influx or even causing K + efflux, while edonors would cause hyperpolarization and then K § influx enhancement (see Fig.…”

Section: Discussionsupporting

confidence: 86%

“…One of the four subunits (gp91 ph~ of the transmembrane enzyme NADPH-oxidase of the PM redox chain of these cells has been identified as an H + pathway associated to this NADPH-oxidase (Henderson 2001). The redox activity generates changes in the PM electric potential that were secondarily responsible for changes in K § flux, by modulating the open or closed state of voltage-gated in-and outward K + channels (Grabov and B6ttger 1994).…”

Section: Introductionmentioning

confidence: 99%

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Effect of dichlorophenolindophenol, dichlorophenolindophenol-sulfonate, and cytochromec on redox capacity and simultaneous net H+/K+ fluxes in aeroponically grown seedling roots of sunflower (Helianthus annuus L.): New evidence for a plasma membrane CN?-resistant redox chain

2001

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Excised roots from axenically grown sunflower seedlings reduced or oxidized exogenously added 2,6-dichlorophenolindophenol (DCIP), DCIP-sulfonate (DCIP-S), and cytochrome c, and affected simultaneous H+/K+ net fluxes. Experiments were performed with nonpretreated "living" and CN(-)-pretreated "poisoned" roots (control and CN(-)-roots). CN(-)-roots showed no H+/K+ net flux activity but still affected the redox state of the compounds tested. The hydrophobic electron acceptor DCIP decreased the rate of H+ efflux in control roots with extension of the maximum rate and optimal pH ranges, then the total net H+ efflux ([symbol: see text]H+) equalled that of the roots without DCIP. The simultaneously measured K+ influx rate was first inhibited, then inverted into efflux, and finally influx recovered to low rates. This effect could not be due to uptake of the negatively charged DCIP, but due to the lower H+ efflux and the transmembrane electron efflux caused by DCIP, which would depolarize the membrane and open outward K+ channels. The different H+ efflux kinetics characteristics, together with the small but significant DCIP reduction by CN(-)-roots were taken as evidence that an alternative CN(-)-resistant redox chain in the plasma membrane was involved in DCIP reduction. The hydrophilic electron acceptor DCIP-S enhanced both H+ and K+ flux rates by control roots. DCIP-S was not reduced, but slightly oxidized by control roots, after a lag, while CN(-)-roots did not significantly oxidize or reduce DCIP-S. Perhaps the hydrophobic DCIP could have access to and drain electrons from an intermediate carrier deep inside the membrane, to which the hydrophilic DCIP-S could not penetrate. Also cytochrome c enhanced [symbol: see text]H+ and [symbol: see text]K+, consistent with the involvement of the CN(-)-resistant redox chain. Control roots did not reduce but oxidize cytochrome c after a 15 min lag, and CN(-)-roots doubled the rate of cytochrome c oxidation without any lag. NADH in the medium spontaneously reduced cytochrome c, but control or CN(-)-roots oxidized cytochrome c, despite of the presence of NADH. In this case CN(-)-roots were less efficient, while control roots doubled the rate of cytochrome c oxidation by CN(-)-roots, after a 10 min lag in which cytochrome c was reduced at the same rate as the medium plus NADH did. CN(-)-roots seemed to have a fully activated CN(-)-resistant branch. The described effects on K+ flux were consistent with the current hypothesis that redox compounds changed the electric membrane potential (de- or hyperpolarization), which induces the opening of voltage-gated in- or outward K+ channels.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Effect of dichlorophenolindophenol, dichlorophenolindophenol-sulfonate, and cytochromec on redox capacity and simultaneous net H+/K+ fluxes in aeroponically grown seedling roots of sunflower (Helianthus annuus L.): New evidence for a plasma membrane CN?-resistant redox chain

2001

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“…Research on plasma membrane redox activity suggests that plant cells are able to reduce exogenous electron acceptors; hexacyanoferrate III (HCF III) is much used in such studies [5][6][7][8]. Ferricyanide reduction by plant cells is accompanied by proton release [9][10][11] and plasma membrane depolarization [12,13]. It has also been reported that plant hormones of the auxin class change the rate of HCF III reduction and proton extrusion by plant cells [14,15].…”

Section: Introductionmentioning

confidence: 99%

The effect of auxins (IAA and 4-Cl-IAA) on the redox activity and medium pH of Zea mays L. root segments

Lekacz

Karcz

2006

Cellular and Molecular Biology Letters

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Indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA) were tested at different concentrations and times for their capacity to change the redox activity and medium pH of maize root segments. The doseresponse surfaces (dose-response curves as a function of time) plotted for redox activity and changes in medium pH (expressed as ΔpH) had a similar shape for both auxins, but differed significantly at the optimal concentrations. With 4-Cl-IAA, the maximal values of redox activity and medium pH changes were observed at 10 -10 M, which was a 100-fold lower concentration than with IAA. Correlations were observed between redox activity and medium pH changes at the optimal concentrations of both IAA and 4-Cl-IAA. The results are discussed herein, taking into account both the concentration of the auxins and the effects produced by them.

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“…By contributing to the root surface area, root hairs are known to play an important role in the absorption of water and nutrients from the soil (Grabov and Bottger, 1994;Lauter et al, 1996;Gahoonia et al, 1997Gahoonia et al, , 2001White, 1998). Additionally, root hairs serve as a site of interaction for fungal and bacterial soil microorganisms, among them nitrogen-fixing bacteria, such as Rhizobium, Azorhizobium, and Bradyrhizobiumin (Mylona et al, 1995;Long, 1996).…”

mentioning

confidence: 99%

Molecular Cloning and Characterization of β-Expansin Gene Related to Root Hair Formation in Barley

2006

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Root hairs are specialized epidermal cells that play a role in the uptake of water and nutrients from the rhizosphere and serve as a site of interaction with soil microorganisms. The process of root hair formation is well characterized in Arabidopsis (Arabidopsis thaliana); however, there is a very little information about the genetic and molecular basis of root hair development in monocots. Here, we report on isolation and cloning of the b-expansin (EXPB) gene HvEXPB1, tightly related to root hair initiation in barley (Hordeum vulgare). Using root transcriptome differentiation in the wild-type/root-hairless mutant system, a cDNA fragment present in roots of wild-type plants only was identified. After cloning of full-length cDNA and genomic sequences flanking the identified fragment, the subsequent bioinformatics analyses revealed homology of the protein coded by the identified gene to the EXPB family. Reverse transcription-PCR showed that expression of HvEXPB1 cosegregated with the root hair phenotype in F 2 progeny of the cross between the hairless mutant rhl1.a and the wild-type Karat parent variety. Expression of the HvEXPB1 gene was root specific; it was expressed in roots of wild-type forms, but not in coleoptiles, leaves, tillers, and spikes. The identified gene was active in roots of two other analyzed root hair mutants: rhp1.a developing root hair primordia only and rhs1.a with very short root hairs. Contrary to this, a complete lack of HvEXPB1 expression was observed in roots of the spontaneous root-hairless mutant bald root barley. All these observations suggest a role of the HvEXPB1 gene in the process of root hair formation in barley.

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Are Redox Reactions Involved in Regulation of K+ Channels in the Plasma Membrane of Limnobium stoloniferum Root Hairs?

Cited by 31 publications

References 22 publications

Effect of dichlorophenolindophenol, dichlorophenolindophenol-sulfonate, and cytochromec on redox capacity and simultaneous net H+/K+ fluxes in aeroponically grown seedling roots of sunflower (Helianthus annuus L.): New evidence for a plasma membrane CN?-resistant redox chain

Effect of dichlorophenolindophenol, dichlorophenolindophenol-sulfonate, and cytochromec on redox capacity and simultaneous net H+/K+ fluxes in aeroponically grown seedling roots of sunflower (Helianthus annuus L.): New evidence for a plasma membrane CN?-resistant redox chain

The effect of auxins (IAA and 4-Cl-IAA) on the redox activity and medium pH of Zea mays L. root segments

Molecular Cloning and Characterization of β-Expansin Gene Related to Root Hair Formation in Barley

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