Mechanisms of abscisic acid-mediated control of stomatal aperture

Abstract

Drought stress triggers an increase in the level of the plant hormone abscisic acid (ABA), which initiates a signaling cascade to close stomata and reduce water loss. Recent studies have revealed that guard cells control cytosolic ABA concentration through the concerted actions of biosynthesis, catabolism as well as transport across membranes. Substantial progress has been made at understanding the molecular mechanisms of how the ABA signaling core module PYR/PYL/RCAR-PP2C-SnRK2 controls the activity of anion channels and thereby stomatal aperture. In this review, we focus on our current mechanistic understanding of ABA signaling in guard cells including the role of the second messenger Ca2+ as well as crosstalk with biotic stress responses.

Reconstitution of Abscisic Acid Signaling from the Receptor to DNA via bHLH Transcription Factors

“…ABA induces stomatal closure to prevent water loss by transpiration and enhances or reduces the expression of numerous genes to aid the plants in adapting to such adverse conditions (Kim et al, 2010;Munemasa et al, 2015). The signaling core complex perceives ABA signal and transmits it to downstream components that induce distinct cellular events (Cutler et al, 2010;Raghavendra et al, 2010;Umezawa et al, 2010).…”

Ion Transport at the Vacuole during Stomatal Movements

“…These are thought to be physiological, and at these potentials, AtCLCa is able to mediate the efflux of anions from the vacuolar lumen into the cytosol. AtOST1 is a central player of ABA signaling in guard cells (Munemasa et al, 2015); thus, AtCLCa is part of this signaling pathway controlling the stomatal aperture.…”

“…Stomata close in response to drought, which is signaled by the phytohormone abscisic acid (ABA). ABA triggers signaling cascades that regulate plasma membrane ion channels by phosphorylation, increases in cytosolic free Ca 2+ concentration, and other second messengers (Roelfsema et al, 2012;Munemasa et al, 2015;Jezek and Blatt, 2017). The changed activities of these ion channels result in large changes in the electric potential gradient across the plasma membrane (i.e.…”

“…In fact, it is more likely that fluxes at the vacuolar and plasma membranes are coordinated. For example, we know that kinases such as Ca 2+ -dependent kinases (CDPKs) and the SNF1-related kinase2.6, AtOST1, regulate ion channels at the plasma membrane (Kollist et al, 2014;Munemasa et al, 2015;Jezek and Blatt, 2017), but it recently became clear that such kinases also have targets at the tonoplast (Latz et al, 2013;Wege et al, 2014). Furthermore, changes in ATP-dependent transport, at both the tonoplast and the plasma membrane, together seem to be required to generate intracellular Ca 2+ signals that initiate stomatal closure (Minguet-Parramona et al, 2016).…”

Fundamental and applied research in ABA signaling: Regulation by ABA of the chromatin remodeling ATPase BRAHMA and biotechnological use of the PP2CA promoter.

“…ABA plays major roles in abiotic and biotic stress responses. It is implicated in guard cell regulation triggering stomatal closure to maintain water balance (Sirichandra et al, 2009, Merilo et al, 2015, Munemasa et al, 2015, antagonizes gibberellins (GAs) effects to fine tune growth in adverse situations (Golldack et al, 2013), controls gene expression to help with plant adaptation to stress (Bechtold et al, 2016) and also has a role in the promotion of plant resistance to pathogens restricting its entrance via stomata (McLachlan et al, 2014). Despite of the well known functions in abiotic and biotic stress, ABA is also important for the regulation of several physiological and developmental events as embryo maturation, promotion of seed desiccation tolerance and dormancy, germination and seedling establishment, primary and lateral root growth and transition from vegetative to reproductive stage (Finkelstein et al, 2002, Cutler et al, 2010, Finkelstein, 2013, Harris, 2015.…”