Signaling Transduction of ABA, ROS, and Ca2+ in Plant Stomatal Closure in Response to Drought

Abstract

Drought is a global threat that affects agricultural production. Plants have evolved several adaptive strategies to cope with drought. Stomata are essential structures for plants to control water status and photosynthesis rate. Stomatal closure is an efficient way for plants to reduce water loss and improve survivability under drought conditions. The opening and closure of stomata depend on the turgor pressure in guard cells. Three key signaling molecules, including abscisic acid (ABA), reactive oxygen species (ROS), and calcium ion (Ca2+), play pivotal roles in controlling stomatal closure. Plants sense the water-deficit signal mainly via leaves and roots. On the one hand, ABA is actively synthesized in root and leaf vascular tissues and transported to guard cells. On the other hand, the roots sense the water-deficit signal and synthesize CLAVATA3/EMBRYO-SURROUNDING REGION RELATED 25 (CLE25) peptide, which is transported to the guard cells to promote ABA synthesis. ABA is perceived by pyrabactin resistance (PYR)/PYR1-like (PYL)/regulatory components of ABA receptor (RCAR) receptors, which inactivate PP2C, resulting in activating the protein kinases SnRK2s. Many proteins regulating stomatal closure are activated by SnRK2s via protein phosphorylation. ABA-activated SnRK2s promote apoplastic ROS production outside of guard cells and transportation into the guard cells. The apoplastic H2O2 can be directly sensed by a receptor kinase, HYDROGEN PEROXIDE-INDUCED CA2+ INCREASES1 (HPCA1), which induces activation of Ca2+ channels in the cytomembrane of guard cells, and triggers an increase in Ca2+ in the cytoplasm of guard cells, resulting in stomatal closure. In this review, we focused on discussing the signaling transduction of ABA, ROS, and Ca2+ in controlling stomatal closure in response to drought. Many critical genes are identified to have a function in stomatal closure under drought conditions. The identified genes in the process can serve as candidate genes for genetic engineering to improve drought resistance in crops. The review summarizes the recent advances and provides new insights into the signaling regulation of stomatal closure in response to water-deficit stress and new clues on the improvement of drought resistance in crops.

Mechanistic Insights on Salicylic Acid Mediated Enhancement of Photosystem II Function in Oregano Seedlings Subjected to Moderate Drought Stress

“…Climate change’s impacts on agriculture and the increasing world population both threaten global food security [ 70 ]. Drought is the main global threat that affects agricultural production [ 71 ]. Photosynthesis is the main process in plants that can be intensely disturbed by environmental parameters [ 72 ].…”

Effect of ethylene pretreatment on tomato plant responses to salt, drought, and waterlogging stress

“…By analyzing the real‐time transpiration rates during salt stress, we observed no significant effect of the ethylene pretreatment (Figure 1b). On the other hand, the stomatal aperture must be carefully regulated to ensure optimal CO 2 uptake for photosynthesis while protecting plants against excess water loss (Nilson & Assmann, 2007; Postiglione & Muday, 2020); otherwise, it could hinder plant growth (Liu, Song, et al, 2022). Our data showed that CO 2 consumption rates declined gradually during salt stress, indicating a reduction in photosynthetic activity and matching the reduction in transpiration (Figure 1b).…”

Exogenous calcium: Its mechanisms and research advances involved in plant stress tolerance

“… Zhang et al. (2020) indicated that an exogenous application of CaCl 2 significantly increased chlorophyll fluorescence indicators (Fv/Fo, Fv/Fm) and the photosynthetic rate in maize, while Liu J et al. (2022) demonstrated that the same treatment onto onion plants reduced cell wall porosity and lowered intracellular ice nucleus temperature.…”

“…The Ca 2+ sensor is an initial stress signal detector as well as a regulator of major plant hormone signals ( Ku et al., 2018 ). Ca 2+ is reportedly involved in the ABA-induced stomatal closure process ( Liu H et al., 2022 ), with which ABA is participated in the initiation and release of Ca 2+ . In addition, both Ca 2+ and ABA regulating kinases target the same metabolic pathway ( Edel and Kudla, 2016 ) through regulating the biosynthesis and signal transmission of jasmonates (JAs) that subsequently adjust the Ca 2+ level, inducing an influx of extracellular Ca 2+ , and temporarily increase its concentration in the nucleo plasma.…”

“…Since several outstanding papers have outlined other functional aspects of Ca 2+ in plants such as its role as a signal messenger, its regulations as a molecular modulator in gene expressions, and its movement through transpiration, etc . ( Edel and Kudla, 2016 ; Marcec et al., 2019 ; Wang X. et al., 2019 ; Liu H. et al., 2022 ), this review has ultimately summarized in detail the research progresses made on studies of exogenous Ca 2+ and its effect on alleviation of seven abiotic stresses, drought, flooding, salt, high temperature, low temperature, heavy metals, and acid rain. At the end, a discussion of perspectives for developing experimental approaches that would take those mechanisms into account for use of different exogenous Ca 2+ in increasing plant tolerance against abiotic stresses is provided.…”