Calcium-based signalling pathways have been identified in stomata

 

Calcium-based signalling systems in guard cells.

by Ng C.K.-Y., McAinsh M.R., Gray J.E., Hunt L., Leckie C.P., Mills L., Hetherington A.M.(2001)

CarL. K.-Y. Ng, Ainsh, Julie E. Gray, Lee Hunt, C. P. Leckie, Lewis Mills, Alistair M. Hetherington

in New Phytol. 151: 109- 120, 2001.- DOI: 10.1046/j.1469-8137.2001.00152.x – 

http://onlinelibrary.wiley.com/doi/10.1046/j.1469-8137.2001.00152.x/full

ABA-induction of H2O2 production in guard cells and H2O2 activated Ca2+ influx in guard cells of Arabidopsis thaliana. (a) Time course of ABA-induction of H2O2 production in guard cells of A. thaliana as visualized by the fluorescent indicator, 2,7-dichlorofluorescein diacetate. (b) 5 mM H2O2-activated Ca2+ influx as visualized by Fura-2 ratios ([Ca2+]cyt) and whole cell currents recorded simultaneously in a guard cell. Holding potential –116 mV (c) 50 µM ABA-induced stomatal closure in wild type (WT) and gca2 guard cells. (d) H2O2-induced stomatal closure in wild type (WT) and gca2 guard cells. Reproduced from Pei et al. (2000) with permission. © 2000 Macmillan Magazines Ltd, UK. – http://onlinelibrary.wiley.com/store/10.1046/j.1469-8137.2001.00152.x/asset/image_n/NPH_152_f3.gif?v=1&t=iyve8fy4&s=d3be76ad8aed62e73e3debceb906a9dd98b64270

Summary

Calcium is a ubiquitous intracellular signal responsible for controlling numerous cellular processes in both plants and animals. As an example, Ca²⁺ has been shown to be a second messenger in the signal transduction pathways by which stomatal guard cells respond to external stimuli.

Regulated increases in the cytosolic concentration of free calcium ions ([Ca²⁺]_cyt) in guard cells have been observed to be a common intermediate in many of the pathways leading to either opening or closing of the stomatal pore.

This observation has prompted investigations into how specificity is encoded in the Ca²⁺ signal. It has been suggested that the key to generating stimulus-specific calcium signatures lies in the ability to access differentially the cellular machinery controlling calcium influx and release from intracellular stores.

Several important components of the calcium-based signalling pathways have been identified in guard cells including cADPR, phospholipase C–InsP₃, InsP₆ and H₂O₂. These data suggest that the pathways for intracellular mobilization of Ca²⁺ are evolutionarily conserved between plants and animals.

Abbreviations

ABA, abscisic acid; [Ca²⁺]_cyt, cytosolic free calcium concentration; [Ca²⁺]_ext, external calcium concentration; I_K,in; inward-rectifying K⁺ currents; InsP₃, inositol-1,4,5-trisphosphate; InsP₆, inositol hexakisphosphate; PLC, phospholipase C; PLD, phospholipase D; PA, phosphatidic acid; H₂O₂, hydrogen peroxide; AAPK, ABA-activated serine-threonine protein kinase; cADPR, cyclic adenosine 5′-diphosphoribose; U73122, 1-(6-{[17â-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2, 5-dione; RyR; ryanodine receptor; CICR; calcium-induced calcium-release; I_Ca, inward calcium current.