Early events induced by chitosan on plant cells
2008
Amborabé, Bénigne-Ernest | Bonmort, Janine | Fleurat-Lessard, Pierrette | Roblin, Gabriel
Chitosan (a polymer of β-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 μg 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 μg 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.
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