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Time of day modulates low‐temperature Ca2+ signals in Arabidopsis

Time of day modulates low‐temperature Ca2+ signals in Arabidopsis We tested the hypothesis that the circadian clock modulates Ca2+‐based signalling pathways, using low‐temperature (LT)‐induced Ca2+ signals. We investigated the relationship between diurnal and circadian modulation of LT‐induced increases in cytosolic‐free calcium ([Ca2+]cyt), and regulation of [Ca2+]cyt‐dependent outputs of the LT‐signalling network (RD29A transcript abundance and stomatal closure). We measured [Ca2+]cyt non‐invasively using aequorin, and targeted aequorin to the guard cell using a guard cell‐specific GAL4‐green fluorescent protein enhancer trap line. LT caused transient increases in whole plant and guard cell [Ca2+]cyt. In guard cells, the LT‐induced [Ca2+]cyt elevation preceded stomatal closure. In whole plants, the magnitude of LT‐induced [Ca2+]cyt transients, measured from the entire plant or specifically the guard cell, varied with the time of day: LT‐induced [Ca2+]cyt transients were significantly higher during the mid‐photoperiod than at the beginning or end. Diurnal variation in LT‐induced guard cell [Ca2+]cyt increases was not correlated to diurnal variation in LT‐induced stomatal closure. There was circadian modulation of LT‐induced whole plant [Ca2+]cyt increases, which were correlated to the circadian pattern of RD29A induction. In order to understand the significance of LT‐induced [Ca2+]cyt increases, we used a computer simulation to demonstrate that, in guard cells, LT‐induced [Ca2+]cyt increases measured from a population of cells are likely to represent the summation of cold‐induced single‐cell [Ca2+]cyt oscillations. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Plant Journal Wiley

Time of day modulates low‐temperature Ca2+ signals in Arabidopsis

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References (96)

Publisher
Wiley
Copyright
Copyright © 2006 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0960-7412
eISSN
1365-313X
DOI
10.1111/j.1365-313X.2006.02933.x
pmid
17227550
Publisher site
See Article on Publisher Site

Abstract

We tested the hypothesis that the circadian clock modulates Ca2+‐based signalling pathways, using low‐temperature (LT)‐induced Ca2+ signals. We investigated the relationship between diurnal and circadian modulation of LT‐induced increases in cytosolic‐free calcium ([Ca2+]cyt), and regulation of [Ca2+]cyt‐dependent outputs of the LT‐signalling network (RD29A transcript abundance and stomatal closure). We measured [Ca2+]cyt non‐invasively using aequorin, and targeted aequorin to the guard cell using a guard cell‐specific GAL4‐green fluorescent protein enhancer trap line. LT caused transient increases in whole plant and guard cell [Ca2+]cyt. In guard cells, the LT‐induced [Ca2+]cyt elevation preceded stomatal closure. In whole plants, the magnitude of LT‐induced [Ca2+]cyt transients, measured from the entire plant or specifically the guard cell, varied with the time of day: LT‐induced [Ca2+]cyt transients were significantly higher during the mid‐photoperiod than at the beginning or end. Diurnal variation in LT‐induced guard cell [Ca2+]cyt increases was not correlated to diurnal variation in LT‐induced stomatal closure. There was circadian modulation of LT‐induced whole plant [Ca2+]cyt increases, which were correlated to the circadian pattern of RD29A induction. In order to understand the significance of LT‐induced [Ca2+]cyt increases, we used a computer simulation to demonstrate that, in guard cells, LT‐induced [Ca2+]cyt increases measured from a population of cells are likely to represent the summation of cold‐induced single‐cell [Ca2+]cyt oscillations.

Journal

The Plant Journal – Wiley

Published: Dec 1, 2006

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