Early events induced by chitosan on plant cells.
Chitosan (a polymer of beta-1,4-glucosamine residues) is a deacetylated derivative of chitin which presents antifungal properties and acts as a potent elicitor of plant resistance against fungal pathogens. Attention was focused in this study on the chitosan-induced early events in the elicitation chain. Thus, it was shown that chitosan triggered in a dose-dependent manner rapid membrane transient depolarization of Mimosa pudica motor cells and, correlatively, a transient rise of pH in the incubation medium of pulvinar tissues. By using plasma membrane vesicles (PMVs), it was specified that a primary site of action of the compound is the plasma membrane H(+)-ATPase as shown by its inhibitory effect on the proton pumping and the catalytic activity of the enzyme up to 250 microg ml(-1). As a consequence, chitosan treatment modified H(+)-mediated processes, in particular it inhibited the uptake of the H(+)-substrate co-transported sucrose and valine, and inhibited the light-induced H(+)/K(+)-mediated turgor reaction of motor cells. The present data also allowed the limit of the cytotoxicity of the compound to be established close to a concentration of 100 microg ml(-1) at the plasma membrane level. As a consequence, chitosan could be preferably used in plant disease control as a powerful elicitor rather than a direct antifungal agent.
University of Poitiers, Laboratoire de Biochimie, Physiologie et Biologie Moléculaires Végétales, FRE CNRS 3091, 40, Avenue du Recteur Pineau, F-86022 Poitiers cedex, France.
Bénigne-Ernest
BE
Amborabé
Janine
J
Bonmort
Pierrette
P
Fleurat-Lessard
Gabriel
G
Roblin
D001692:Biological Transport; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D016764:Cell Polarity; D048271:Chitosan / Q000494:pharmacology*; D018699:Coated Vesicles / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D031298:Mimosa / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D010940:Plant Proteins; D048271:Chitosan; D006180:Proton-Translocating ATPases