Plasma Membrane Fluidity: An Environment Thermal Detector in Plants (original) (raw)
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Plants are incapable of escaping from a changing environment. Therefore, they have developed sophisticated mechanisms for acclimation and survival under unfavorable conditions, such as unfavorable temperatures. Low temperatures induce a number of ...
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Temperature has a direct effect at the cellular level on an organism. For instance, in the case of biomembranes, cooling causes lipids to lose entropy and pack closely together. Reducing temperature should, in the absence of other factors, increase the viscosity of a lipid membrane. We have investigated the effect of temperature variation on plasma membrane (PM) viscosity.
Febs Letters, 2006
Membrane rigidification could be the first step of cold perception in poikilotherms. We have investigated its implication in diacylglycerol kinase (DAGK) activation by cold stress in suspension cells from Arabidopsis mutants altered in desaturase activities. By lateral diffusion assay, we showed that plasma membrane rigidification with temperature decrease was steeper in cells deficient in oleate desaturase than in wild type cells and in cells overexpressing linoleate desaturase. The threshold for the activation of the DAGK pathway in each type of cells correlated with this order of rigidification rate, suggesting that cold induced-membrane rigidification is upstream of DAGK pathway activation.
Early steps in cold sensing by plant cells: the role of actin cytoskeleton and membrane fluidity
Plant Journal, 2000
Many plants acquire freezing tolerance through cold acclimatization (CA), a prolonged exposure to low but non-freezing temperatures at the onset of winter. CA is associated with gene expression that requires transient calcium in¯ux into the cytosol. Alfalfa (Medicago sativa) cells treated with agents blocking this in¯ux are unable to cold-acclimatize. Conversely, chemical agents causing increased calcium in¯ux induce cold acclimatization-speci®c (cas) gene expression in alfalfa at 25LC. How low temperature triggers calcium in¯ux is, however, unknown. We report here that induction of a CA-speci®c gene (cas30), calcium in¯ux and freezing tolerance at 4LC are all prevented by cell membrane¯uidization, but, conversely, are induced at 25LC by membrane rigidi®cation. cas30 expression and calcium in¯ux at 4LC are also prevented by jasplakinolide (JK), an actin micro®lament stabilizer, but induced at 25LC by the actin micro®lament destabilizer cytochalasin D (CD). JK blocked the membrane rigidi®er-induced, but not the calcium channel agonist-induced cas30 expression at 25LC. These ®ndings indicate that cytoskeleton re-organization is an integral component in low-temperature signal transduction in alfalfa cell suspension cultures, serving as a link between membrane rigidi®cation and calcium in¯ux in CA.
The Plant journal : for cell and molecular biology, 2002
Mitogen-activated protein kinases (MAPKs) appear to be ubiquitously involved in signal transduction during eukaryotic responses to extracellular stimuli. In plants, no heat shock-activated MAPK has so far been reported. Also, whereas cold activates specific plant MAPKs such as alfalfa SAMK, mechanisms of such activation are unknown. Here, we report a heat shock-activated MAPK (HAMK) immunologically related to ERK (Extracellular signal-Regulated Kinase) superfamily of protein kinases. Molecular mechanisms of heat-activation of HAMK and cold-activation of SAMK were investigated. We show that cold-activation of SAMK requires membrane rigidification, whereas heat-activation of HAMK occurs through membrane fluidization. The temperature stress- and membrane structure-dependent activation of both SAMK and HAMK is mimicked at 25 degrees C by destabilizers of microfilaments and microtubules, latrunculin B and oryzalin, respectively; but is blocked by jasplakinolide, a stabilizer of actin mic...
International Journal of Molecular Sciences
Cold stress is one of the major factors limiting global crop production. For survival at low temperatures, plants need to sense temperature changes in the surrounding environment. How plants sense and respond to the earliest drop in temperature is still not clearly understood. The plasma membrane and its adjacent extracellular and cytoplasmic sites are the first checkpoints for sensing temperature changes and the subsequent events, such as signal generation and solute transport. To understand how plants respond to early cold exposure, we used a mass spectrometry-based phosphoproteomic method to study the temporal changes in protein phosphorylation events in Arabidopsis membranes during 5 to 60 min of cold exposure. The results revealed that brief cold exposures led to rapid phosphorylation changes in the proteins involved in cellular ion homeostasis, solute and protein transport, cytoskeleton organization, vesical trafficking, protein modification, and signal transduction processes....
Environmental and Experimental Botany, 2010
Confronted to changes in temperatures, plants readjust their biochemical makeup to adapt and survive. The fact that temperature changes can induce cellular responses indicates that temperature is sensed and that the temperature signal is transduced into the cell. While the signalling pathways triggered temperature changes are well described, the way plants sense temperature is often considered as elusive. This review is focused on the mechanisms by which plants sense temperature. We show that plants have no internal thermometer as such, but that the very alterations in cellular equilibria triggered by temperature changes act as networked thermostats to sense heat and cold. Amongst these temperature-sensitive devices, we identified membrane fluidity, protein conformation, cytoskeleton depolymerization, and metabolic reactions. Besides, other molecular switches are proposed. A model of the temperature sensing "machinery" is proposed. Finally, we discuss the specificities of temperature sensing, showing that signalling events can feed-back perception steps.
Temperature-induced lipocalin is required for basal and acquired thermotolerance in Arabidopsis
Plant, Cell & Environment, 2009
Plant temperature-induced lipocalins (TILs) have been shown to be responsive to heat stress (HS), but the nature of this response was unknown. In this study, a reverse genetic approach was taken to elucidate the role of Arabidopsis TIL1 (At5g58070) in thermotolerance. A T-DNA knock-out line of TIL1 (til1-1) showed severe defects in basal (BT) and acquired thermotolerance (AT), which could be complemented by introducing the wild-type gene. However, over-expression of TIL1 did not significantly enhance thermotolerance in transgenic plants. TIL1 is peripherally associated with plasma membrane. Transcriptomic analysis showed that the heat shock response in til1-1 seedlings was about the same as in the wild-type plants except the expression of TIL1. The level of TIL1 did not affect the temperature threshold for heat shock protein induction. Ion leakage analysis revealed no significant difference in membrane stability between the wild-type and til1-1 seedlings. These results suggest that TIL1 is not involved in regulating membrane fluidity or stability. Nevertheless, the mutant plants were also more sensitive than the wild type to tert-butyl hydroperoxide, a reagent that induces lipid peroxidation. Taken together, these data indicate that TIL1 is an essential component for thermotolerance and probably functions by acting against lipid peroxidation induced by severe HS.
A Lipidomic Approach to Identify Cold-Induced Changes in Arabidopsis Membrane Lipid Composition
Methods in Molecular Biology, 2014
Lipidomic analysis using electrospray ionization triple quadrupole mass spectrometry can be employed to monitor lipid changes that occur during cold and freezing stress of plants. Here we describe the analysis of Arabidopsis thaliana polar glycerolipids with normal and oxidized acyl chains, sampled during cold and freezing treatments. Mass spectral data are processed using the online capabilities of LipidomeDB Data Calculation Environment.