Heterotrimeric G-proteins involved in the MeJA regulated ion flux and stomatal closure in Arabidopsis thaliana

Abstract

Heterotrimeric G-proteins play an important role in plant signalling pathways. The plant hormone methyl jasmonate (MeJA) can induce stomatal closure in many plant species. The signal cascade in MeJA-induced stomatal closure has been studied previously. However, the function of G proteins in this process has not yet been evaluated. In this study, the stomatal movement induced by MeJA in the wild-type Arabidopsis thaliana (L. Heynh.) (WS), Gα subunit loss-of-function mutant gpa1–1 and gpa1–2 guard cells were measured. Further, the transmembrane ion flux (H+, Ca2+ and K+) and reactive oxygen species (ROS) experiments were performed in guard cells from WS, GDP-β-S pre-treated WS, gpa1–1 and gpa1–2 using non-invasive micro-test technique (NMT) and confocal technique. It was observed that the MeJA-induced stomatal closure was abolished in guard cells of gpa1 mutants. GDP-β-S pre-treatment and gpa1 mutants impaired the MeJA-activated H+ efflux, Ca2+ influx and K+ efflux. The accumulation of ROS in gpa1–1 and gpa1–2 guard cells was also lower than that in WS guard cells under MeJA treatment. These results suggested that Gα subunits are involved in regulating the signal events in JA signal pathway and stomatal closure.

Hydrogen Sulfide Positively Regulates Abscisic Acid Signaling through Persulfidation of SnRK2.6 in Guard Cells

“…Net stomatal fluxes of Ca 2+ were measured with a non-invasive microsensing system (NMT100-SIM-XY/YG; Younger, USA) according to methods described by Sun et al (2009) and Yan et al (2015) with some modifications. Silanized glass micropipettes (4-5 mm aperture; XYPG120-2; Xuyue Science and Technology, Beijing, China) were first filled with a backfilling solution (100 mM CaCl 2 ), then the front of the micropipettes was filled with 40-50 mm of selective liquid ion exchanger to create the Ca 2+ -selective sensor.…”

The role of plasma membrane H+‐ATPase in jasmonate‐induced ion fluxes and stomatal closure in Arabidopsis thaliana

“…In turn, the accumulation of ROS activates the Ca 2+ channel and the resulting elevation of free cytoplasmic Ca 2+ triggers PM anion channels leading to cell depolarization (Pei et al ., ; Murata et al ., ). Our previous results on the relevant ion transporter genes also showed that MeJA upregulated the expression of the anion channel genes SLAC1 and SLAC3 (Yan et al ., ), which suggested that the anion channels were activated. The depolarization of the PM further promoted efflux of K + from the cell through the depolarization‐dependent outward K + channels (Schroeder et al ., ).…”

“…Evans () indicated that exogenous MeJA treatment downregulated the inward K + channels but upregulated the outward K + channels. We observed the K + efflux triggered by MeJA in Col‐0 guard cells, combined with the upregulation of GORK , but downregulation of the inward K + channel gene KAT1 (Yan et al ., ), and this finally resulted in stomatal closure. However, when the PM H + ‐ATPase was inhibited or mutated, the K + efflux was attenuated.…”

“…Net fluxes of H + , Ca 2+ and K + were measured using NMT as described (Xu et al, 2006;Sun et al, 2009;Yan et al, 2015). Ionselective electrodes were constructed as follows: pre-pulled and silanized glass micropipettes (2-4 lm aperture) were first filled with a backfilling solution (H + : 40 mM KH 2 PO 4 and 15 mM NaCl, pH 7.0; Ca 2+ : 100 mM CaCl 2 ; K + : 100 mM KCl) to a length of about 1 cm from the tip.…”

Herbivore exposure alters ion fluxes and improves salt tolerance in a desert shrub

“…The ion flux is calculated on the basis of Fick's law of diffusion, J 0 = ﹣ D ·( dc / dx ), where J 0 represents the ion flux (in units of pmol·cm −2 ·s −1 ), dc / dx is the ion concentration gradient, and D is the ion diffusion constant (in cm −2 ·sec −1 ) in a particular medium (Sun, Li, Yin, Shangguan, & Xu, ). Net K + , Na + , H + , and Ca 2+ fluxes during plant response to stresses were measured using an NMT system (NMT‐YG‐100; Younger USA LLC, Amherst, MA, USA; Sun, Chen, et al, ; Sun, Dai, et al, ; Yan, Luo, et al, ; Yan, McLamore, et al, ; Zhang et al, ). Prepulled silanized glass micropipettes (diameter = 4–5 μm, XY‐DJ‐01; Xuyue [Beijing] Science and Technology Co. Ltd., Beijing, China) were prepared and calibrated as described below.…”