| Oxidative defence reactions in sunflower roots induced by methyl-jasmonate and methyl-salicylate and their relation with calcium signalling. | |
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MedLine Citation:
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PMID: 19763783 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ca(2+) plays a critical role as second messenger in the signal-response coupling of plant defence responses, and methyl-jasmonate and methyl-salicylate are important components of signal transduction cascades activating plant defences. When intact axenic non-induced seedling roots of sunflower were treated with different Ca(2+) concentrations up to 1 mM, there was no significant increase in O(2)(*-) generation or DMAB-MBTH peroxidase (extracellular, ECPOX) activities in the apoplast, probably because these roots had enough Ca(2+) in their exo- and endocellular reservoirs. Both activities were strongly inhibited by the RBOH-NADPH oxidase inhibitor DPI and by the Ca(2+) surrogate antagonist La(3+), but the voltage-dependent Ca(2+) channel blocker verapamil was only inhibitory at concentrations higher than those active on animal L-type Ca(2+) channels. Concentrations >5 mM EGTA (chelating Ca(2+) in the apoplast) and Li(+) (inhibiting PI cycle dependent endogenous Ca(2+) fluxes) also inhibited both activities. W7, inhibitor of binding of Ca-CaM to its target protein, enhanced both activities, but the inactive analogue W5 showed a similar effect. Our data suggest that Ca(2+) from exocellular and, to a lesser extent, from endocellular stores is involved in oxidative activities, and that RBOH-NADPH oxidase is the main system supporting them. Ca(2+) activation of the PM cytosolic side of RBOH-NADPH oxidase is probably the key to Ca(2+) involvement in these processes. Roots induced by MeJA or MeSA showed significant enhancement of both oxidative activities, as corresponding to the oxidative burst evoked by the two phytohormones in the root apoplast. But while ECPOX activity showed a response to the effectors similar to that described above for non-induced roots, O(2)(*-) generation activity in the apoplast of induced roots was insensitive to EGTA, verapamil and Li(+), the inhibitors of exogenous and endogenous Ca(2+) fluxes; only DPI and La(3+) were inhibitory. As exogenously added 0.1 mM Ca(2+) also increased O (2) (.-) generation, we propose that, in these roots, activation of RBOH-NADPH oxidase by Ca(2+) could be regulated by Ca(2+) sensors in the apoplast. |
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Authors:
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Inmaculada Garrido; Francisco Espinosa; M Carmen Alvarez-Tinaut |
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Publication Detail:
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Type: Journal Article Date: 2009-09-08 |
Journal Detail:
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Title: Protoplasma Volume: 237 ISSN: 1615-6102 ISO Abbreviation: Protoplasma Publication Date: 2009 Oct |
Date Detail:
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Created Date: 2010-01-21 Completed Date: 2010-03-23 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9806853 Medline TA: Protoplasma Country: Austria |
Other Details:
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Languages: eng Pagination: 27-39 Citation Subset: IM |
Affiliation:
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Area de Fisiolog?a Vegetal, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain. igarridoc@unex.es |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acetic Acids
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pharmacology* Calcium Signaling / physiology* Cyclopentanes / pharmacology* Helianthus / metabolism* Oxidation-Reduction Oxylipins / pharmacology* Plant Roots / metabolism* Reactive Oxygen Species Salicylates / pharmacology* |
| Chemical | |
Reg. No./Substance:
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0/Acetic Acids; 0/Cyclopentanes; 0/Oxylipins; 0/Reactive Oxygen Species; 0/Salicylates; 119-36-8/methyl salicylate; 1211-29-6/methyl jasmonate |
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