title: Early changes in membrane permeability, production of oxidative burst and modification of PAL activity induced by ergosterol in cotyledons of Mimosa pudica.
abstract: Ergosterol (a fungal membrane component) was shown to induce transient influx of protons and membrane hyperpolarization in cotyledonary cells of Mimosa pudica L. By contrast, chitosan (a fungal wall component with known elicitor properties) triggered membrane depolarization. In the processes induced by ergosterol, a specific desensitization was observed, since cells did not react to a second ergosterol application but did respond to a chitosan treatment. This comparative study correspondingly shows that ergosterol and chitosan were perceived in a distinct manner by plant cells. Generation of O2*-, visualized by infiltration with nitroblue tetrazolium, was displayed in organs treated with ergosterol and chitosan. This AOS production was preceded by an increase in activity of NADPH oxidase measured in protein extracts of treated cotyledons. In all the previously described processes, cholesterol had no effect, thereby indicating that ergosterol specifically induced these physiological changes known to participate in the reaction chain activated by characteristic elicitors. Contrary to chitosan, ergosterol did not greatly activate secondary metabolism as shown by the small change in content of free phenolics and by the low modification in activity of PAL, the key enzyme of this metabolic pathway. Therefore, future studies have to clarify the signalling cascade triggered by ergosterol recognition.
authors.affiliation: Laboratoire de Biochimie, Physiologie et Biologie Moléculaire Végétales, UMR CNRS 6161, University of Poitiers, 40, Avenue du Recteur Pineau, F-86022 Poitiers, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Rossard
authors.forename: Estelle
authors.initials: E
authors.lastname: Luini
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Pérault
authors.forename: Janine
authors.initials: J
authors.lastname: Bonmort
authors.forename: Gabriel
authors.initials: G
authors.lastname: Roblin
mesh_terms: D000946:Antigens, Fungal; D002463:Cell Membrane Permeability; D048271:Chitosan / Q000378:metabolism; D018548:Cotyledon / Q000378:metabolism; D004594:Electrophysiology; D004875:Ergosterol / Q000378:metabolism*; D031298:Mimosa / Q000378:metabolism* / Q000382:microbiology; D019255:NADPH Oxidases / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D011522:Protons; D016897:Respiratory Burst
chemical_list: D000946:Antigens, Fungal; D010636:Phenols; D011522:Protons; D048271:Chitosan; D019255:NADPH Oxidases; D010650:Phenylalanine Ammonia-Lyase; D004875:Ergosterol