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Iwase J.,University of Kitakyushu | Furukawa H.,University of Kitakyushu | Hiramatsu T.,University of Kitakyushu | Bouteau F.,University of Kitakyushu | And 11 more authors.
Journal of Experimental Botany

The impact of copper ions on the oxidative and calcium signal transductions, leading to cell death in plant cells, have been documented. Copper induces a series of biological and chemical reactions in plant cells including the oxidative burst reflecting the production of reactive oxygen species and the stimulation of calcium channel opening allowing a transient increase in cytosolic calcium concentrations. These early events, completed within a few minutes after the contact with copper, are known to trigger the development of cell death. The effects of DNA fragments with copper-binding motifs as novel plant cell-protecting agents were assessed using cell suspension cultures of transgenic tobacco (Nicotiana tabacum L., cell line BY-2) expressing the aequorin gene. The addition of GC-rich double-stranded DNA fragments, prior to the addition of copper ions, effectively blocked both the copper-induced calcium influx and cell death. In addition, the DNA-Cu complex examined was shown to possess superoxide-scavenging catalytic activity, suggesting that DNA-mediated protection of the cells from copper toxicity is due to the removal of superoxide. Lastly, a possible mechanism of DNA-Cu interaction and future applications of these DNA fragments in the protection of plant roots from metal toxicity or in aid of phyto-remediation processes are discussed. © The Author 2014. Source

Kawano T.,University of Kitakyushu | Kawano T.,University of Florence | Kawano T.,University Paris Diderot | Bouteau F.,University of Florence | And 2 more authors.
Plant Cell Reports

It is well recognized that salicylic acid (SA) acts as a natural signaling molecule involved in both local and systemic plant defense responses upon attacks by pathogens. Recently, cellular SA receptors and a number of SA-related phloem-mobile signals were identified. Here, we compare the old and up-to-date concepts of plant defense signaling events involving SA. Finally, the crosstalk between intracellular and extracellular SA signaling events leading to long-distance spread of signals was outlined by focusing on the modes of both the short- and long-distance signaling events involving the actions of SA. For the above purpose, two distinct conceptual models for local SA perception and signaling mechanisms in the intracellular and extracellular paths (referred to as models i and ii, respectively) were proposed. In addition to two local SA perception models, we propose that the long-distance SA action could be attributed to three different modes, namely, (iii) local increase in SA followed by transport of SA and SA intermediates, (iv) systemic propagation of SA-derived signals with both chemical and electrical natures without direct movement of SA, and (v) integrated crosstalk allowing alternately repeated secondary signal propagation and biosynthesis of SA and/or conversion of inert SA intermediates to free SA finally contributing to the systemic spread of SA-derived signals. We review here that the long-distance SA signaling events (models iii-v), inevitably involve the mechanisms described in the local signaling models (models i and ii) as the key pieces of the crosstalk. © 2013 Springer-Verlag Berlin Heidelberg. Source

de Paepe R.,Institute Of Biologie Des Plantes | Lemaire S.D.,Sorbonne Universites | Danon A.,Sorbonne Universites
Plant Signaling and Behavior

Cardiolipin is a key phospholipid most specifically found in the membrane of mitochondria in yeasts, plants, and animals. Cardiolipins are essential for the maintenance, the integrity, and the dynamics of mitochondria. In most eukaryotes mitochondria play a central role in the response and adaptation to stress conditions especially through their importance in the control of programmed cell death. To assess the impact of the absence of cardiolipin, knock-down of the expression of cardiolipin synthase, the last enzyme of cardiolipin synthesis pathway in eukaryotes has been performed in yeasts, animals, and plants. These studies showed that cardiolipin is not only important for mitochondrial ultrastructure and for the stability of respiratory complexes, but it is also a key player in the response to stress, the formation of reactive oxygen species, and the execution of programmed cell death. © 2014 Landes Bioscience. Source

Tran D.,University Paris Diderot | Tran D.,Institute Of Biologie Des Plantes | El-Maarouf-Bouteau H.,University Pierre and Marie Curie | Rossi M.,University of Florence | And 12 more authors.
New Phytologist

Ion fluxes are ubiquitous processes in the plant and animal kingdoms, controlled by fine-tuned regulations of ion channel activity. Yet the mechanism that cells employ to achieve the modification of ion homeostasis at the molecular level still remains unclear. This is especially true when it comes to the mechanisms that lead to cell death. In this study, Arabidopsis thaliana cells were exposed to ozone (O3). Ion flux variations were analyzed by electrophysiological measurements and their transcriptional regulation by RT-PCR. Reactive oxygen species (ROS) generation was quantified by luminescence techniques and caspase-like activities were investigated by laser confocal microscopy. We highlighted the delayed activation of K+ outward-rectifying currents after an O3-induced oxidative stress leading to programmed cell death (PCD). Caspase-like activities are detected under O3 exposure and could be decreased by K+ channel blocker. Molecular experiments revealed that the sustained activation of K+ outward current could be the result of an unexpected O2 ·- post-transcriptional regulation of the guard cell outward-rectifying K+ (GORK) channels. This consists of a likely new mode of regulating the processing of the GORK mRNA, in a ROS-dependent manner, to allow sustained K+ effluxes during PCD. These data provide new mechanistic insights into K+ channel regulation during an oxidative stress response. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust. Source

Tran D.,University Paris Diderot | Tran D.,Institute Of Biologie Des Plantes | Rossi M.,University of Florence | Biligui B.,University Paris Diderot | And 9 more authors.
Plant Signaling and Behavior

Using A. thaliana cultured cells; we recently reported new insights regarding the effect of acute O3 exposure.1-3 This consist in an oxidative dependent controlled cell death process involving cell shrinkage due to an early activation of anion channel1 and a delayed activation of K+ outward currents,2 but also to early events like Ca2+ influx or singlet oxygen production possibly linked to mitochondrial dysfunction.1 Here we provide evidence that most of these early events act downstream of caspase-like activities as recently demonstrated for K+ channel activation.2 © 2013 Landes Bioscience. Source

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