Changes in the Growth, Chemical Composition, and Antioxidant Activity in the Aquatic Plant Wolffia arrhiza (L.) Wimm. (Lemnaceae) Exposed to Jasmonic Acid

The present study was undertaken to test the influence of exogenously applied jasmonic acid (JA) at concentrations of 0.01-100 mu M upon the growth and metabolism of the aquatic plant Wolffia arrhiza (Lemnaceae). JA acted in a concentration-dependent manner. JA at 0.1 mu M stimulated plant growth and accumulation of cellular components (proteins, monosaccharides, chlorophylls, phaeophytins, and carotenoids). Treatment with JA at 0.1 mu M enhanced W. arrhiza viability by the induction of biomass production and increased the level of photosynthetic pigments, monosaccharides, and soluble proteins. Moreover, JA at 0.1 mu M activated the enzymatic (catalase, ascorbate peroxidase, NADH peroxidase) and nonenzymatic antioxidant (ascorbate, glutathione) system in W. arrhiza and, therefore, suppressed lipid peroxidation. In contrast, decreases in fresh weight, major photosynthetic pigments, monosaccharides, and soluble protein content were observed in W. arrhiza exposed to 100 mu M JA. JA applied at 100 mu M also stimulated the formation of lipid peroxides which are responsible for membrane damage. In the presence of 100 mu M JA, antioxidant enzyme (catalase, ascorbate peroxidase, NADH peroxidase) activity and ascorbate as well as glutathione content were inhibited. The data support the hypothesis that JA plays an important role in W. arrhiza growth and metabolism, regulating oxidative status by direct influence on the enzymatic as well as nonenzymatic antioxidant machinery.