Article

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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    • "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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    • "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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    • "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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