Whole-cell K+ current across the plasma membrane of guard cells from a grass: Zea mays

Fairley-Grenot, Katrina; Assmann, Sarah M.

doi:10.1007/bf00196258

Cited by 72 publications

(41 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Guard cell protoplasts were isolated from leaf epidermal peels using the enzymatic digestion protocol described by Fairley-Grenot and Assmann (1992a). Growth of Arabidopsis plants (Wassilewskija ecotype) and isolation of Arabidopsis guard cell protoplasts were performed as described by Hosy et al (2003).…”

Section: Patch Clamp On Guard Cell Protoplastsmentioning

confidence: 99%

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

North

Grignon

et al. 2005

Plant Cell

View full text Add to dashboard Cite

An inward Shaker K+ channel identified in Zea mays (maize), ZmK2.1, displays strong regulation by external K+ when expressed in Xenopus laevis (African clawed frog) oocytes or COS cells. ZmK2.1 is specifically activated by K+ with an apparent Km close to 15 mM independent of the membrane hyperpolarization level. In the absence of K+, ZmK2.1 appears to enter a nonconducting state. Thus, whatever the membrane potential, this maize channel cannot mediate K+ influx in the submillimolar concentration range, unlike its relatives in Arabidopsis thaliana. Its expression is restricted to the shoots, the strongest signal (RT-PCR) being associated with vascular/bundle sheath strands. Based on sequence and gene structure, the closest relatives of ZmK2.1 in Arabidopsis are K+ Arabidopsis Transporter 1 (KAT1) (expressed in guard cells) and KAT2 (expressed in guard cells and leaf phloem). Patch-clamp analyses of guard cell protoplasts reveal a higher functional diversity of K+ channels in maize than in Arabidopsis. Channels endowed with regulation by external K+ similar to that of ZmK2.1 (channel activity regulated by external K+ with a Km close to 15 mM, regulation independent of external Ca2+) constitute a major component of the maize guard cell inward K+ channel population. The presence of such channels in maize might reflect physiological traits of C4 and/or monocotyledonous plants

show abstract

Section: Patch Clamp On Guard Cell Protoplastsmentioning

confidence: 99%

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

North

Grignon

et al. 2005

Plant Cell

View full text Add to dashboard Cite

show abstract

“…Thus, there is no doubt that inhibition of the proton pump by Ca2+ inhibits stomatal opening because inward-rectifying K + channels are also inactivated by Ca2+ (Schroeder and Hagiwara, 1989;Fairley-Grenot and Assmann, 1992). However, inhib.ition of the pump upon the increase of [Ca2+]cyl in guard cells may provide a key step for the initiation of stomatal closing.…”

Section: Dlscusslonmentioning

confidence: 99%

Cytosolic Concentration of Ca2+ Regulates the Plasma Membrane H+-ATPase in Guard Cells of Fava Bean.

1995

View full text Add to dashboard Cite

Opening of the stomata i s driven by the light-activated plasma membrane proton pumping ATPase, although the activation and inactivation mechanism of the enzyme is not known. In this study, we show that the H+-ATPase in guard CellS is reversibly inhibited by Ca2+ at physiological concentrations. Isolated microsomal membranes of guard cell protoplasts from fava bean exhibited vanadate-sensitive, ATP-dependent proton pumping. The activity was inhibited almost completely by 1 pM Ca2+ with a half-inhibitory concentration at 0.3 pM and was restored immediately by the addition of 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid, a calcium chelating reagent. Similar reversible inhibition by Ca2+ was shown by the generation of electrical potential in the membranes. Activity of ATP hydrolysis was inhibited similarly by Ca2+ in the same membrane preparations. The addition of 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid and EGTA, Ca2+ chelators, to epidermal peels of fava bean induced stomatal opening in the dark, and the opening was suppressed by vanadate. This suggests that the lowered cytosolic Ca2+ activated the proton pump i n vivo and that the activated pump elicited stomatal opening. lnhibition of H+-ATPase by Ca2+ may depolarize the membrane potential and could be a key step in the process of stomatal closing through activation of the anion channels. Furthermore, similar inhibition of the proton pumping and ATP hydrolysis by Ca2+ was found in isolated plasma membranes of mesophyll cells of fava bean. These results suggest that Ca2+ regulates the activity of plasma membrane H+-ATPases in higher plant cells, thereby modulating stomatal movement and other cellular processes i n plants.

show abstract

“…However, GC are much smaller and comprise a minor fraction of the total cells in a leaf. Although guard cell protoplasts have been isolated mostly at a small scale from several plant species (12)(13)(14)(15)(16), it is often technically challenging to obtain GC with good quantity and good quality. With a full genome sequenced, Arabidopsis has become a model species for plant biology research.…”

mentioning

confidence: 99%

Functional Differentiation of Brassica napus Guard Cells and Mesophyll Cells Revealed by Comparative Proteomics

Zhu

Dai

McClung

et al. 2009

Molecular & Cellular Proteomics

111

115

View full text Add to dashboard Cite

Guard cells (GC)1 are highly specialized cells that form tiny pores called stomata on the leaf surface. When environmental conditions change, guard cells can rapidly change shape so that the pores open or close to control leaf gas exchange and water transpiration. Mesophyll cells (MC) are mainly parenchyma cells between the upper and lower epidermis specialized for photosynthesis. Previous studies that focused on guard cell metabolism and response to environmental signals have revealed important features of functional differentiation of GC (1, 2). Compared with MC, GC contain few chloroplasts with very limited structures and thus possess very low photosynthetic capability. The Calvin cycle in GC only assimilates 2-4% of CO 2 fixed in MC (3). In contrast, GC contain abundant mitochondria and display a high respiratory rate, suggesting that oxidative phosphorylation is an important source of ATP to fuel the guard cell machinery (4). Using microarrays covering just one-third of the Arabidopsis genome, Leonhardt et al. (5) observed a differential abscisic acid (ABA) modulation of many guard cell ABA signaling components as well as key enzymes involved in carbon metabolism in GC and MC. This only available large scale genomics study identified 1309 guard cell expressed genes of which 64 transcripts mainly involved in transcription, signaling, and cytoskeleton were preferentially expressed in GC compared with MC. However, functional grouping of the genes revealed only a 1.9% higher representation of photosynthesis genes in MC than in GC. The percentages of genes in all other categories such as protein turnover, defense, signaling, channels and transporters, and metabolism are similar between the two distinct cell types (5). These proteins are known to play specific roles in guard cell functions (6). This highlights the necessity of studying guard cell functions at the protein level.To date, there have been very few analyses of single celltype proteomes in plants. Proteome analyses of trichomes from Arabidopsis (7) and tobacco (8) and root hairs from soybean (9) exist but have identified fewer than 100 proteins per proteome. The proteomes of pollen from different species have been relatively well studied, but the pollen grains are not single cells because they contain two/three-cell gametophytes (10). A critical factor for large scale proteomics analFrom the ‡Department

show abstract

Whole-cell K+ current across the plasma membrane of guard cells from a grass: Zea mays

Cited by 72 publications

References 33 publications

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

Cytosolic Concentration of Ca2+ Regulates the Plasma Membrane H+-ATPase in Guard Cells of Fava Bean.

Functional Differentiation of Brassica napus Guard Cells and Mesophyll Cells Revealed by Comparative Proteomics

Contact Info

Product

Resources

About

Whole-cell K+ current across the plasma membrane of guard cells from a grass: Zea mays

Cited by 72 publications

References 33 publications

Regulation by External K+ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

Regulation by External K+ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

Cytosolic Concentration of Ca2+ Regulates the Plasma Membrane H+-ATPase in Guard Cells of Fava Bean.

Functional Differentiation of Brassica napus Guard Cells and Mesophyll Cells Revealed by Comparative Proteomics

Contact Info

Product

Resources

About

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range

Regulation by External K⁺ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range