AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells

Meyer, Stefan; Mumm, Patrick; Imes, Dennis; Endler, Anne; Weder, Barbara; Al-Rasheid, Khaled A. S.; Geiger, Dietmar; Marten, Irene; Martinoia, Enrico; Hedrich, Rainer

doi:10.1111/j.1365-313x.2010.04302.x

Cited by 329 publications

(430 citation statements)

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“…However, they make sense in light of the importance of membrane voltage in determining net solute flux (Thiel et al, 1992;Chen et al, 2012;Jezek and Blatt, 2017). The ALMT channel activates, positivegoing, with a midpoint voltage near 260 mV (Dietrich and Hedrich, 1998;Meyer et al, 2010;Hills et al, 2012) and, therefore, imposes a strong, voltage-dependent brake on membrane hyperpolarization for initial solute uptake. Conversely, H-ATPase activity is key to hyperpolarizing the plasma membrane, and its activity must be suppressed for rapid stomatal closure (Merlot et al, 2007;Minguet-Parramona et al, 2016).…”

Section: Resultsmentioning

confidence: 99%

“…However, an appreciable hub also is associated with the tonoplast TPK channel. For the initial rate of stomatal opening (A), hubs of interdependence are associated with parameters for the plasma membrane Ca 2+ -ATPase and the ALMT anion channel, which plays a key role in the control of membrane voltage and stomatal closing (Meyer et al, 2010;Wang et al, 2014a;MinguetParramona et al, 2016;Jezek and Blatt, 2017 (2016) also noted previously that the oscillation number was subject to the dynamic range of stomatal apertures for a given set of conditions: in other words, the number of cycles needed to transit from the open to the closed state. Thus, it was not surprising that we found weak interdependencies only, largely in the range of 0.02 to 0.04 and including the interaction between VCa in and the VCa-ATPase.…”

Section: Resultsmentioning

confidence: 99%

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Global Sensitivity Analysis of OnGuard Models Identifies Key Hubs for Transport Interaction in Stomatal Dynamics

et al. 2017

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The physical requirement for charge to balance across biological membranes means that the transmembrane transport of each ionic species is interrelated, and manipulating solute flux through any one transporter will affect other transporters at the same membrane, often with unforeseen consequences. The OnGuard systems modeling platform has helped to resolve the mechanics of stomatal movements, uncovering previously unexpected behaviors of stomata. To date, however, the manual approach to exploring model parameter space has captured little formal information about the emergent connections between parameters that define the most interesting properties of the system as a whole. Here, we introduce global sensitivity analysis to identify interacting parameters affecting a number of outputs commonly accessed in experiments in Arabidopsis (Arabidopsis thaliana). The analysis highlights synergies between transporters affecting the balance between Ca 2+ sequestration and Ca 2+ release pathways, notably those associated with internal Ca 2+ stores and their turnover. Other, unexpected synergies appear, including with the plasma membrane anion channels and H + -ATPase and with the tonoplast TPK K + channel. These emergent synergies, and the core hubs of interaction that they define, identify subsets of transporters associated with free cytosolic Ca 2+ concentration that represent key targets to enhance plant performance in the future. They also highlight the importance of interactions between the voltage regulation of the plasma membrane and tonoplast in coordinating transport between the different cellular compartments.Stomata form the major pathway for CO 2 entry across the leaf epidermis for photosynthesis and for water loss by transpiration from the leaf tissues. Pairs of guard cells surround the stomatal pore and regulate the aperture. These cells balance the demand for CO 2 with that for water conservation. Guard cells expand and contract to open and close the pore. They take up and lose solutes, notably K + and Cl 2 , which, together with the synthesis and metabolism of organic solutes, especially malate, provide the osmotic driving force for these changes in aperture (Kim et al., 2010;Roelfsema and Hedrich, 2010;Lawson and Blatt, 2014). Thus, membrane transport comprises the principal set of effectors of a regulatory network that ensures the homeostatic control of the guard cell for stomatal aperture.Environmental signals, notably light, CO 2 , water availability, and the hormone abscisic acid, affect this network, modulating transport and solute accumulation. Research at the cellular and molecular levels has focused on these inputs and their contributions to stomatal movements. A large body of work has highlighted Ca 2+ -independent and Ca 2+ -dependent signaling, the latter including elevations in free cytosolic Ca 2+ concentration ([Ca 2+ ] i ), protein kinase and phosphatase activities, which inactivate inward-rectifying K + channels and activate Cl 2 (anion) channels, as well as the changes in cytosolic pH that ...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Global Sensitivity Analysis of OnGuard Models Identifies Key Hubs for Transport Interaction in Stomatal Dynamics

et al. 2017

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“…In contrast, in A. thaliana clade II contains 5 members including AtALMT9 and 6 (Kovermann et al 2007;Meyer et al 2011). Interestingly, clade III incorporates only 1 member in V. vinifera, whereas in Arabidopsis there are 4 members, amongst them AtALMT12 (Meyer et al 2010). …”

Section: Cloning Vvalmt9 a Homologue Of The Arabidopsis Vacuolar Chamentioning

confidence: 99%

The vacuolar channel VvALMT9 mediates malate and tartrate accumulation in berries of Vitis vinifera

Angeli

Baetz

Francisco

et al. 2013

Planta

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Vitis vinifera L. represents an economically important fruit species. Grape and wine flavour is made from a complex set of compounds. The acidity of berries is a major parameter in determining grape berry quality for wine making and fruit consumption. Despite the importance of malic and tartaric acid (TA) storage and transport for grape berry acidity, no vacuolar transporter for malate or tartrate has been identified so far. Some members of the aluminium-activated malate transporter (ALMT) anion channel family from Arabidopsis thaliana have been shown to be involved in mediating malate fluxes across the tonoplast. Therefore, we hypothesised that a homologue of these channels could have a similar role in V. vinifera grape berries. We identified homologues of the Arabidopsis vacuolar anion channel AtALMT9 through a TBLASTX search on the V. vinifera genome database. We cloned the closest homologue of AtALMT9 from grape berry cDNA and designated it VvALMT9. The expression profile revealed that VvALMT9 is constitutively expressed in berry mesocarp tissue and that its transcription level increases during fruit maturation. Moreover, we found that VvALMT9 is targeted to the vacuolar membrane. Using patch-clamp analysis, we could show that, besides malate, VvALMT9 mediates tartrate currents which are higher than in its Arabidopsis homologue. In summary, in the present study we provide evidence that VvALMT9 is a vacuolar malate channel expressed in grape berries. Interestingly, in V. vinifera, a tartrate-producing plant, the permeability of the channel is apparently adjusted to TA. AbstractVitis vinifera L. represents an economically important fruit species. Grape and wine flavour is made of a complex set of compounds. The acidity of berries is a major parameter in determining grape berry quality for wine making and for fruit consumption. Despite the importance of malic and tartaric acid storage and transport for grape berry acidity no vacuolar transporter for malate or tartrate has been identified so far. Some members of the ALMT (ALuminium activated Malate Transporter) anion channel family from Arabidopsis thaliana have been shown to be involved in mediating malate fluxes across the tonoplast. Therefore, we hypothesized that a homologue of these channels could have a similar role in V. vinifera grape berries. We identified homologues of the Arabidopsis vacuolar anion channel AtALMT9 through a TBLASTX search on the V. vinifera genome database. We cloned the closest homologue of AtALMT9 from grape berry cDNA and designated it VvALMT9. The expression profile revealed that VvALMT9 is constitutively expressed in berry mesocarp tissue and that its transcription level increases during fruit maturation. Moreover, we found that VvALMT9 is targeted to the vacuolar membrane. Using patch-clamp analysis we could show that, besides malate, VvALMT9 mediates tartrate currents which are higher than in its Arabidopsis homologue. In summary, in the present study we provide evidence that VvALMT9 is a vacuolar malate channel expr...

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“…In guard cells ALMTs mediate anion fluxes through the plasma and vacuolar membranes and are involved in the regulation of stomatal movements (3)(4)(5)(6). The first ALMT channel described, TaALMT1, was identified as a gene associated to aluminum resistance (2).…”

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confidence: 99%

Cytosolic Nucleotides Block and Regulate the Arabidopsis Vacuolar Anion Channel AtALMT9

Zhang

Martinoia

Angeli

2014

Journal of Biological Chemistry

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Background:AtALMT9 is an intracellular anion channel regulating stomata aperture. Results: ATP interacts with the pore of AtALMT9 competing with vacuolar anions and modifying the voltage dependence of this ion channel. Conclusion: Cytosolic nucleotides and vacuolar anions directly modulate the transport activity of AtALMT9. Significance: Regulation of intracellular transporters is crucial for their physiological functions.

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AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells

Cited by 329 publications

References 47 publications

Global Sensitivity Analysis of OnGuard Models Identifies Key Hubs for Transport Interaction in Stomatal Dynamics

Global Sensitivity Analysis of OnGuard Models Identifies Key Hubs for Transport Interaction in Stomatal Dynamics

The vacuolar channel VvALMT9 mediates malate and tartrate accumulation in berries of Vitis vinifera

Cytosolic Nucleotides Block and Regulate the Arabidopsis Vacuolar Anion Channel AtALMT9

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