Tissue‐specific expression of <i>Arabidopsis AKT1</i> gene is consistent with a role in K<sup>+</sup> nutrition

Lagarde, Delphine; Basset, Mireille; Lepetit, Marc; Conéjéro, Geneviève; Gaymard, Frédéric; Astruc, Suzette; Grignon, Claude

doi:10.1046/j.1365-313x.1996.09020195.x

Cited by 336 publications

(282 citation statements)

References 0 publications

Supporting

Mentioning

263

Contrasting

Unclassified

Order By: Relevance

“…How-Yi Wang et al 827 npg ever, little is known about the regulatory mechanism of these K + transporters. AKT1 has been identified as an important dual-affinity inward-rectifying K + channel participating in K + uptake from soil into cells in Arabidopsis roots [9][10][11][12]. More recently, we have demonstrated that AKT1 activity is positively regulated by a protein kinase AtCIPK23, and AtCIPK23 is in turn activated by AtCBL1 or AtCBL9 [13].…”

Section: Introductionmentioning

confidence: 94%

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Wang

et al. 2010

Cell Res

View full text Add to dashboard Cite

Potassium transporters play crucial roles in K + uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassium channel AtKC1, encoded by the AtLKT1 gene cloned from the Arabidopsis thaliana low-K + (LK)-tolerant mutant Atlkt1, significantly regulates AKT1-mediated K + uptake under LK conditions. Under LK conditions, the Atkc1 mutants maintained their root growth, whereas wild-type plants stopped their root growth. Lesion of AtKC1 significantly enhanced the tolerance of the Atkc1 mutants to LK stress and markedly increased K + uptake and K + accumulation in the Atkc1-mutant roots under LK conditions. Electrophysiological results showed that AtKC1 inhibited the AKT1-mediated inward K + currents and negatively shifted the voltage dependence of AKT1 channels. These results demonstrate that the 'silent' K + channel α-subunit AtKC1 negatively regulates the AKT1-mediated K + uptake in Arabidopsis roots and consequently alters the ratio of root-to-shoot under LK stress conditions. Keywords: Arabidopsis; potassium channel; low-K + stress; AKT1; AtKC1 Cell Research (2010) IntroductionPotassium is an essential mineral element for plant growth and development, and it plays essential roles in many important physiological and biochemical processes in living plant cells, such as regulation of enzyme activation, electrical neutralization, osmoregulation, control of membrane potential, co-transport of sugars, and so on [1,2]. Plant growth and development need millimolar K + in the soil or growth medium, but typical K + concentration at the interface of roots and soils is within micromolar range [3]. Thus, plants often encounter low-K + (LK) stress under natural conditions. Although different plants or different genotypes of a plant species show varied K + utilization efficiency [4], most plants show K + -deficient symptom under LK stress, typically leaf chlorosis and subsequent inhibition of plant growth and development [5].Absorption of K + by plant cells and K + translocation between different tissues and organs in plants are mediated by plant K + transporters and channels [2,6,7]. Over the past decade, a large number of genes encoding plant K + transporters and channels, particularly for Arabidopsis, have been characterized [6][7][8]. These K + transporters vary in K + affinity, kinetics, transcriptional modulation, regulatory mechanism, etc [2,[6][7][8], and they compose a complex system for plant K + uptake and translocation. Among these K + transporters and channels, members of the Shaker K + channel family are well characterized for their potential functions and are probably the most important for K + uptake and transport in Arabidopsis [8] Recent reports showed that channel heterotetramerization is a key regulatory mechanism for K + channels, which was found not only in animals [14][15][16] but also in plants [17,18]. Different kinds of potassium channel subunits may assemble together to form functional heteromer...

show abstract

Section: Introductionmentioning

confidence: 94%

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Wang

et al. 2010

Cell Res

View full text Add to dashboard Cite

show abstract

“…Thus, KATZ is predominantly expressed in guard cells (Nakamura et al, 1995) and AKTZ is predominantly expressed in the epidermis, cortex, and endodermis of the mature root, and also in hyadothodes (Cao et al, 1995;Lagarde et al, 1996). KSTZ, the potato K A T l homolog, is also expressed in guard cells and flowers, indicating the conservation of tissue-specific expression in different species (Miiller-Rober et al, 1995).…”

Section: P-domainmentioning

confidence: 99%

Roles of Higher Plant K+ Channels

Maathuis¹,

Ichida²,

Sanders³

et al. 1997

Plant Physiology

196

123

View full text Add to dashboard Cite

Living organisms maintain a cellular solute composition very different from that of the externa1 environment. This implicitly requires the transport of solutes across the cell membrane, and ion channels are integral membrane proteins that play indispensable roles in such transport. In the past dozen years, radical advances have aided in our understanding of ion channel function and regulation in higher plants. Nowhere are these advances more striking than with respect to K+ channels, where the synergistic application of electrophysiological, cell biological, physiological, and molecular techniques has demonstrated an array of channel types playing diverse but defined roles in plant physiology.The major function of K+ channels in animal cells is that of membrane voltage control and short-term repolarization of the membrane. Although K+ channels in plants share similar roles in the regulation of the membrane voltage, early research on guard cells led to the model that shows that plant K+ channels in addition provide important pathways for long-term physiological K+ uptake and release. An extensive range of recent studies suggests diverse longterm transport functions of plant K+ channels, including participation in osmotically driven movements, solute loading into the xylem, cation nutrition, and, by virtue of the presence of K+ channels at endomembranes, intracellular solute redistribution and cytosolic volume control. Most plant K+ channels remain activated for long periods of time, which is critica1 for this proposed long-term transport function of K+ channels in plants. Because higher plant K+ channels are proposed to play a role in regulating both the influx and the efflux of K+ from cells, activity of these channels may impinge upon aspects of turgor and water relations of a11 plant cells. In this Update we focus on important principles of plant K+ channel function and on the proposed physiological roles of specific plant K + channel types in the plasma membrane and tonoplast (Fig. 1A) of different plant cells.

show abstract

“…For the GUS assay, plants were either cultivated in vitro under the same conditions or grown in soil mixed with vermiculite in a greenhouse under continuous light at 228C. GUS histochemical staining was performed according to Lagarde et al (1996).…”

Section: Cloning Of Complementation and Gus Expression Constructs: Exmentioning

confidence: 99%

Inactivation of Thioredoxin Reductases Reveals a Complex Interplay between Thioredoxin and Glutathione Pathways in Arabidopsis Development

et al. 2007

View full text Add to dashboard Cite

NADPH-dependent thioredoxin reductases (NTRs) are key regulatory enzymes determining the redox state of the thioredoxin system. The Arabidopsis thaliana genome has two genes coding for NTRs (NTRA and NTRB), both of which encode mitochondrial and cytosolic isoforms. Surprisingly, plants of the ntra ntrb knockout mutant are viable and fertile, although with a wrinkled seed phenotype, slower plant growth, and pollen with reduced fitness. Thus, in contrast with mammals, our data demonstrate that neither cytosolic nor mitochondrial NTRs are essential in plants. Nevertheless, in the double mutant, the cytosolic thioredoxin h3 is only partially oxidized, suggesting an alternative mechanism for thioredoxin reduction. Plant growth in ntra ntrb plants is hypersensitive to buthionine sulfoximine (BSO), a specific inhibitor of glutathione biosynthesis, and thioredoxin h3 is totally oxidized under this treatment. Interestingly, this BSO-mediated growth arrest is fully reversible, suggesting that BSO induces a growth arrest signal but not a toxic accumulation of activated oxygen species. Moreover, crossing ntra ntrb with rootmeristemless1, a mutant blocked in root growth due to strongly reduced glutathione synthesis, led to complete inhibition of both shoot and root growth, indicating that either the NTR or the glutathione pathway is required for postembryonic activity in the apical meristem.

show abstract

Tissue‐specific expression of Arabidopsis AKT1 gene is consistent with a role in K⁺ nutrition

Cited by 336 publications

References 0 publications

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Roles of Higher Plant K+ Channels

Inactivation of Thioredoxin Reductases Reveals a Complex Interplay between Thioredoxin and Glutathione Pathways in Arabidopsis Development

Contact Info

Product

Resources

About

Tissue‐specific expression of Arabidopsis AKT1 gene is consistent with a role in K+ nutrition

Cited by 336 publications

References 0 publications

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress

Roles of Higher Plant K+ Channels

Inactivation of Thioredoxin Reductases Reveals a Complex Interplay between Thioredoxin and Glutathione Pathways in Arabidopsis Development

Contact Info

Product

Resources

About

Tissue‐specific expression of Arabidopsis AKT1 gene is consistent with a role in K⁺ nutrition