The dual effect of abscisic acid on stomata

INRA, UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060, Montpellier, France.
New Phytologist (Impact Factor: 6.55). 10/2012; 197(1). DOI: 10.1111/nph.12013
Source: PubMed

ABSTRACT The classical view that the drought-related hormone ABA simply acts locally at the guard cell level to induce stomatal closure is questioned by differences between isolated epidermis and intact leaves in stomatal response to several stimuli. We tested the hypothesis that ABA mediates, in addition to a local effect, a remote effect in planta by changing hydraulic regulation in the leaf upstream of the stomata. By gravimetry, porometry to water vapour and argon, and psychrometry, we investigated the effect of exogenous ABA on transpiration, stomatal conductance and leaf hydraulic conductance of mutants described as ABA-insensitive at the guard cell level. We show that foliar transpiration of several ABA-insensitive mutants decreases in response to ABA. We demonstrate that ABA decreases stomatal conductance and down-regulates leaf hydraulic conductance in both the wildtype Col-0 and the ABA-insensitive mutant ost2-2. We propose that ABA promotes stomatal closure in a dual way via its already known biochemical effect on guard cells and a novel, indirect hydraulic effect through a decrease in water permeability within leaf vascular tissues. Variability in sensitivity of leaf hydraulic conductance to ABA among species could provide a physiological basis to the isohydric or anisohydric behaviour.

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Available from: Bertrand Muller, Aug 14, 2015
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    • "Plants have developed various mechanisms to cope with drought that depend on the duration and intensity of the water deficit, and their responses occur at different temporal and spatial scales, from cell to whole tree level (Jones et al., 2002). One first response to soil drought is stomatal closure, an avoidance mechanism mediated by the hormone abscisic acid (Pantin et al., 2013). A main consequence of stomatal closure is the decrease in CO 2 influx and assimilation, which can lead to carbon depletion. "
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    ABSTRACT: Genetic studies of response to water deficit in adult trees are limited by low throughput of the usual phenotyping methods in the field. Here, we aimed at overcoming this bottleneck, applying a new methodology using airborne multispectral imagery and in planta measurements to compare a high number of individuals.An apple tree population, grafted on the same rootstock, was submitted to contrasting summer water regimes over two years. Aerial images acquired in visible, near- and thermal-infrared at three dates each year allowed calculation of vegetation and water stress indices. Tree vigour and fruit production were also assessed. Linear mixed models were built accounting for date and year effects on several variables and including the differential response of genotypes between control and drought conditions.Broad-sense heritability of most variables was high and 18 quantitative trait loci (QTLs) independent of the dates were detected on nine linkage groups of the consensus apple genetic map. For vegetation and stress indices, QTLs were related to the means, the intra-crown heterogeneity, and differences induced by water regimes. Most QTLs explained 15-20% of variance.Airborne multispectral imaging proved relevant to acquire simultaneous information on a whole tree population and to decipher genetic determinisms involved in response to water deficit. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
    Journal of Experimental Botany 07/2015; DOI:10.1093/jxb/erv355 · 5.79 Impact Factor
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    • "A - induced dephosphorylation of PIP2 ; 1 Ser - 280 seen in Arabidopsis plantlets ( Kline et al . , 2010 ) likely corresponds to PIP2 ; 1 from veins , the predominant sites of expression of this aquaporin in leaves . This de - phosphorylation may mediate the inhibition of leaf hydraulic conductivity by the hormone ( Shatil - Cohen et al . , 2011 ; Pantin et al . , 2013 ) . Thus , our work indicates that a single PIP isoform can exhibit opposite cell - specific responses to the same stim - ulus , through cell - specific regulations at distinct phosphoryla - tion sites ."
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    ABSTRACT: Stomatal movements in response to environmental stimuli critically control the plant water status. Although these movements are governed by osmotically driven changes in guard cell volume, the role of membrane water channels (aquaporins) has remained hypothetical. Assays in epidermal peels showed that knockout Arabidopsis thaliana plants lacking the Plasma membrane Intrinsic Protein 2;1 (PIP2;1) aquaporin have a defect in stomatal closure, specifically in response to abscisic acid (ABA). ABA induced a 2-fold increase in osmotic water permeability (Pf) of guard cell protoplasts and an accumulation of reactive oxygen species in guard cells, which were both abrogated in pip2;1 plants. Open stomata 1 (OST1)/Snf1-related protein kinase 2.6 (SnRK2.6), a protein kinase involved in guard cell ABA signaling, was able to phosphorylate a cytosolic PIP2;1 peptide at Ser-121. OST1 enhanced PIP2;1 water transport activity when coexpressed in Xenopus laevis oocytes. Upon expression in pip2;1 plants, a phosphomimetic form (Ser121Asp) but not a phosphodeficient form (Ser121Ala) of PIP2;1 constitutively enhanced the Pf of guard cell protoplasts while suppressing its ABA-dependent activation and was able to restore ABA-dependent stomatal closure in pip2;1. This work supports a model whereby ABA-triggered stomatal closure requires an increase in guard cell permeability to water and possibly hydrogen peroxide, through OST1-dependent phosphorylation of PIP2;1 at Ser-121. © 2015 American Society of Plant Biologists. All rights reserved.
    The Plant Cell 07/2015; DOI:10.1105/tpc.15.00421 · 9.58 Impact Factor
    • "It has been documented that ABA induce an osmotic efflux from guard cells reducing their turgor and, consequently, closing stoma (Zhang and Davies, 1990; Assmann and Shimazaki, 1999; Blatt, 2000). Also it has been proven recently that ABA might exert a control on leaf hydraulic conductance having an indirect effect on stomatal conductance (Pantin et al., 2013). In grapevines, there is wide and convincing evidence on the relationship between g s and ABA (Correia et al., 1995; Lovisolo et al., 2008; Pou et al., 2008; Romero et al., 2012; Speirs et al., 2013; Tramontini et al., 2014). "
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    ABSTRACT: Knowledge about regulation of stomatal conductance is necessary to improve grapevine water use efficiency. The vast range of grapevine cultivars may allow choosing the best-performing ones to global changing conditions provided the understanding and characterization of their physiological responses. In this study, a comparison between two cultivars (Tempranillo and Grenache) with different reputation in water use efficiency was performed during two experimental years in field-conditions. Water relations, leaf gas exchange and abscisic acid (ABA) dynamics were measured at different phenological stages along the growing seasons. A clear difference in the regulation of leaf water relations was observed between cultivars under water stress conditions. Specifically, results showed that there is a clear relationship between hydraulic conductance (Kh) and stomatal regulation. However, ABA can exert a differentiating role on stomatal control during different stages within the grapevine growth period. Furthermore, this study showed that differences in osmotic adjustment could lead to substantial differentiation in the stomatal regulation and the leaf water use efficiency.
    Agricultural Water Management 07/2015; 156:1-9. DOI:10.1016/j.agwat.2015.03.011 · 2.33 Impact Factor
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