Open or Close the Gate – Stomata Action Under the Control of Phytohormones in Drought Stress Conditions

Abstract

Two highly specialized cells, the guard cells that surround the stomatal pore, are able to integrate environmental and endogenous signals in order to control the stomatal aperture and thereby the gas exchange. The uptake of CO2 is associated with a loss of water by leaves. Control of the size of the stomatal aperture optimizes the efficiency of water use through dynamic changes in the turgor of the guard cells. The opening and closing of stomata is regulated by the integration of environmental signals and endogenous hormonal stimuli. The various different factors to which the guard cells respond translates into the complexity of the network of signaling pathways that control stomatal movements. The perception of an abiotic stress triggers the activation of signal transduction cascades that interact with or are activated by phytohormones. Among these, abscisic acid (ABA), is the best-known stress hormone that closes the stomata, although other phytohormones, such as jasmonic acid, brassinosteroids, cytokinins, or ethylene are also involved in the stomatal response to stresses. As a part of the drought response, ABA may interact with jasmonic acid and nitric oxide in order to stimulate stomatal closure. In addition, the regulation of gene expression in response to ABA involves genes that are related to ethylene, cytokinins, and auxin signaling. In this paper, recent findings on phytohormone crosstalk, changes in signaling pathways including the expression of specific genes and their impact on modulating stress response through the closing or opening of stomata, together with the highlights of gaps that need to be elucidated in the signaling network of stomatal regulation, are reviewed.

The Mitigation Effects of Exogenous Hydrogen Peroxide when Alleviating Seed Germination and Seedling Growth Inhibition on Salinity-Induced Stress in Barley

“…Many environmental factors such as biotic and abiotic stresses can modulate stomatal reactions [41]. The variation of stomatal responses under abiotic stress [42] made it possible to use these structures in determining stress tolerance [43].…”

Aquaporins facilitate hydrogen peroxide entry into guard cells to mediate ABA- and pathogen-triggered stomatal closure

“…While key proteins such as glutathione peroxidase 3 (AtGPX3) (45) or ABI2 protein phosphatase (46) are known to be regulated through ROS-dependent oxidation, other cellular targets of H 2 O 2 may play an important role during stomatal closure and not restricted to guard cell responses to flg22 and ABA. Ethylene and methyl jasmonate (MeJA) also induce H 2 O 2 production (14,47) to promote stomatal closure, thereby protecting the plant from dehydration and/or pathogen attacks. While AtPIP2;1 is the only detected PIP2 expressed in guard cells (48), several PIP1s are also expressed, which may transport H 2 O 2 (24,30).…”

Study of the Interactive Effects of Calcium and Abscisic Acid on Drought Stressed Triticum aestivum Seedlings

“…ABA treatment induces changes in gene expression in more than 10% of the Arabidopsis genome (Zeller et al, 2009), resulting in the increased expression of stress associated and signaling component transcripts (Yamaguchi-Shinozaki & Shinozaki, 2005). The increase in ABA content under drought or salinity stress conditions stimulates stomatal closure and the accumulation of osmo-compatible solutes, thus increasing the plant's capacity to cope with stress conditions (Seki et al, 2007 andDaszkowska-Golec &Szarejko, 2013).…”