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Oligoguluronates elicit an oxidative burst in the brown algal kelp Laminaria digitata

Author:
Kupper, F.C., Kloareg, B., Guern, J., Potin, P.
Source:
Plant physiology 2001 v.125 no.1 pp. 278-291
ISSN:
0032-0889
Subject:
Laminaria, defense mechanisms, oxidation, alginates, oligosaccharides, chemical structure, hydrogen peroxide, histochemistry, developmental stages, plant morphology, plant anatomy, emissions
Abstract:
Oligomeric degradation products of alginate elicited a respiratory and oxidative burst in the sporophytes of the kelp Laminaria digitata. The generation of activated oxygen species (AOS), O2-, and H2O2 was detected at the single cell level, using nitroblue tetrazolium precipitation and a redox-sensitive fluorescent probe, respectively. The oxidative burst involved diphenyleneiodonium-sensitive AOS-generating machinery and its amplitude depended on the type of tissue. After a first elicitation plants were desensitized for about 3 h. The activity of alginate oligosaccharides was dose dependent, saturating around 40 micromolar. It was also structure-dependent, with homopolymeric blocks of alpha-1,4-L-guluronic acid, i.e. the functional analogs of oligogalacturonic blocks in pectins, being the most active signals. The perception of oligoguluronate signals resulted in a strong efflux of potassium. Pharmacological dissection of the early events preceding the emission of AOS indicated that the transduction chain of oligoguluronate signals in L. digitata is likely to feature protein kinases, phospholipase A2, as well as K+, Ca2+, and anion channels.
Agid:
667525