Chitosan enhances leaf membrane stability and antioxidant enzyme activities in apple seedlings under drought stress
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Chitosan is a cationic marine polysaccharide with unique bioactive properties that make it an effective scavenger of reactive oxygen species. Chitosan application has been suggested as an aid for reducing oxidative injury caused by drought stress in crop plants. In order to confirm the antioxidant effects of exogenous chitosan, cell membrane stability and antioxidant enzyme activities were analyzed in leaves of apple seedlings placed under a period of drought stress. Pretreatment of apple seedling leaves with chitosan solution (20, 50, 100, 150 and 200 mg l−1) prior to drought stress significantly decreased electrolyte leakage and the production of malondialdehyde in the leaves, while increasing antioxidant enzyme activities (superoxide dismutase, catalase), following imposition of drought stress conditions. An optimum response was obtained at a chitosan concentration of 100 mg l−1. When apple seedlings were pretreated with 100 mg l−1 of chitosan, cell membrane stability and antioxidant enzyme activities were enhanced for 21 days of drought treatment. Following restoration of moisture and a repeated drought stress, similar results were obtained on day 35. It is proposed that chitosan may act as an exogenous antioxidant that enhances resistance to oxidative stress during drought.
KeywordsAntioxidative enzymes Chitosan Lipid peroxidation Malus sieversii Oxidative stress
Reactive oxygen species
We are grateful to professor Mrs. Marilyn White (Brigham Young University, USA) for the critical reading of the manuscript. Illuminating comments from the chief editor and anonymous reviewers are also appreciated. This research was mainly supported by “The National High Technology Research and Development Program (“863”Program) of China (2007AA10Z231)” and “The National Key Fund Project (30230230)”.
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