Cesium‐insensitive mutants of <i>Arabidopsis thaliana</i>

Sheahan, John J.; Ribeiro-Neto, Leonidio; Sussman, Michael R.

doi:10.1111/j.1365-313x.1993.00647.x

Cited by 52 publications

(7 citation statements)

References 30 publications

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“…Fifth, 5-pS IRC activity is closely correlated to the K + status of the growth medium and moreover, exhibits a quantitative enhancement of activity in accord with that observed for Rb + influx in the millimolar range. In addition, we have found that the Cs+-tolerant A. thaliana mutant csi52 (Sheahan et al 1993) which is altered in K + uptake and K + homeostasis, exhibits a concomitant change in 5-pS IRC channel properties (data not shown).…”

Section: Mechanisms Of K + Uptake In Arabidopsis Thalianamentioning

confidence: 90%

Contrasting roles in ion transport of two K+-channel types in root cells of Arabidopsis thaliana

Maathuis

Sanders

1995

Planta

124

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Plant roots accumulate K+ over a range of external concentrations. Root cells have evolved at least two parallel plasma-membrane K+ transporters which operate at millimolar and micromolar external [K+]: high-affinity K+ uptake is energised by symport with H+, while low-affinity uptake is assumed to occur via ion channels. To determine the role of ion channels in low-affinity K+ uptake, a characterisation of the principal K(+)-selective ion channels in the plasma membrane of Arabidopsis thaliana (L.) Heynh. cv. Columbia roots was undertaken. Two classes of K(+)-selective channels were frequently observed: one inward (IRC) and one outward (ORC) rectifying with unitary conductances of 5 pS, 20 pS (IRCs) and 15 pS (ORC), measured in symmetrical 10 mM KCl. The dominant IRC (5 pS) and ORC (15 pS) were highly cation-selective (PCl:PK < 0.025) but less selective amongst monovalent cations (PNa:PK approximately 0.17-0.3). Both the IRC and the ORC were blocked by Ba2+, Cs+ and tetra-ethyl-ammonium, whereas 4-aminopyridine and quinidine selectively inhibited the ORC. The ORC open probability was steeply voltage-dependent and ORC activation potentials were close to the potassium equilibrium potential (EK+), enabling ORCs to conduct mainly outward, but occasionally inward, K+ current. By contrast, gating of the 5-pS IRC was weakly voltage-ependent and IRC gating was invariably restricted to membrane potentials more negative than EK+, ensuring K+ transport was always inwardly directed.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Mechanisms Of K + Uptake In Arabidopsis Thalianamentioning

confidence: 90%

Contrasting roles in ion transport of two K+-channel types in root cells of Arabidopsis thaliana

Maathuis

Sanders

1995

Planta

124

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“…Cs+ toxicity has been characterized for Arabidopsis seedling growth and was shown to be alleviated by increasing levels of K+ in the external media (Sheahan, 1991;Sheahan et al, 1993). Cesium toxicity is most likely/ mediated by sev-era1 mechanisms and is affected by sekeral genetic loci (Sheahan et al, 1993).…”

Section: Cs+ Toxicity 1s Related To K+ Concentrationmentioning

confidence: 99%

Expression of a Cs + -Resistant Guard Cell K + Channel Confers Cs + -Resistant, Light-Induced Stomatal Opening in Transgenic Arabidopsis

Ichida¹,

Pei²,

Baizabal-Aguirre³

et al. 1997

The Plant Cell

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Inward-rectifying K+ (K+in) channels in the guard cell plasma membrane have been suggested to function as a major pathway for K+ influx into guard cells during stomatal opening. When K+in channels were blocked with external Cs+ in wild-type Arabidopsis guard cells, light-induced stomatal opening was reduced. Transgenic Arabidopsis plants were generated that expressed a mutant of the guard cell K+in channel, KAT1, which shows enhanced resistance to the Cs+ block. Stomata in these transgenic lines opened in the presence of external Cs+. Patch-clamp experiments with transgenic guard cells showed that inward K+(in) currents were blocked less by Cs+ than were K+ currents in controls. These data provide direct evidence that KAT1 functions as a plasma membrane K+ channel in vivo and that K+in channels constitute an important mechanism for light-induced stomatal opening. In addition, biophysical properties of K+in channels in guard cells indicate that components in addition to KAT1 may contribute to the formation of K+in channels in vivo.

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“…Cs+ toxicity has been characterized for Arabidopsis seedling growth and was shown to be alleviated by increasing levels of K+ in the external media (Sheahan, 1991;Sheahan et al, 1993). Cesium toxicity is most likely/ mediated by severa1 mechanisms and is affected by sekeral genetic loci (Sheahan et al, 1993).…”

Section: Cs+ Toxicity 1s Related To K+ Concentrationmentioning

confidence: 99%

“…Cesium toxicity is most likely/ mediated by severa1 mechanisms and is affected by sekeral genetic loci (Sheahan et al, 1993). Interestingly, a Cs+-resistant Arabidopsis mutant, csi52, recently has been shown to affect K+ channel activities and K+ transport in roots (Maathuis and Sanders, 1996).…”

Section: Cs+ Toxicity 1s Related To K+ Concentrationmentioning

confidence: 99%

“…Interestingly, a Cs+-resistant Arabidopsis mutant, csi52, recently has been shown to affect K+ channel activities and K+ transport in roots (Maathuis and Sanders, 1996). Although it is clear that Cs+ affects severa1 enzymes in whole-plant studies (Sheahan et al, 1993), it is still interesting that the block of KATl by Cs+ is also competitively decreased by raising the level of K+ in the external solution (Ichida and Schroeder, 1996). We found here that the effectiveness of Cs+ in blocking stomatal opening in Arabidopsis was also dependent on the external K+ concentration such that Cs+ was ineffective if external K+ concentrations were raised (data not shown).…”

Section: Cs+ Toxicity 1s Related To K+ Concentrationmentioning

confidence: 99%

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Expression of a Cs(+)-resistant guard cell K+ channel confers Cs(+)-resistant, light-induced stomatal opening in transgenic arabidopsis.

et al. 1997

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Inward-rectifying K+ (K+in) channels in the guard cell plasma membrane have been suggested to function as a major pathway for K+ influx into guard cells during stomatal opening. When K+, channels were blocked with external Cs+ in wild-type Arabidopsis guard cells, light-induced stomatal opening was reduced. Transgenic Arabidopsis plants were generated that expressed a mutant of the guard cell K+, channel, KATl, which shows enhanced resistance to the Cs+ block. Stomata in these transgenic lines opened in the presence of external Cs+. Patch-clamp experiments with transgenic guard cells showed that inward K+i, currents were blocked less by Cs+ than were K+ currents in controls. These data provide direct evidence that KATl functions as a plasma membrane K+ channel in vivo and that K+, channels constitute an important mechanism for light-induced stomatal opening. In addition, biophysical properties of K+, channels in guard cells indicate that components in addition to KATl may contribute to the formation of K+in channels in vivo.

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Cesium‐insensitive mutants of Arabidopsis thaliana

Cited by 52 publications

References 30 publications

Contrasting roles in ion transport of two K+-channel types in root cells of Arabidopsis thaliana

Contrasting roles in ion transport of two K+-channel types in root cells of Arabidopsis thaliana

Expression of a Cs + -Resistant Guard Cell K + Channel Confers Cs + -Resistant, Light-Induced Stomatal Opening in Transgenic Arabidopsis

Expression of a Cs(+)-resistant guard cell K+ channel confers Cs(+)-resistant, light-induced stomatal opening in transgenic arabidopsis.

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