Effect of Cadmium on the Level of Isoprenoid-Derived Phytohormones in Duckweed Wolffia arrhiza

Journal of Plant Growth Regulation - Wolffia arrhiza (L.) Horkel ex Wimm. is an aquatic plant belonging to the Lemnaceae family. It does not have leaves, stems, and roots, flowers rarely occur,...     

The effect of natural and synthetic auxins on the growth,metabolite content and antioxidant response of green alga Chlorella vulgaris (Trebouxiophyceae)

The effect of exogenously applied natural [indole-3-acetic acid (IAA), phenylacetic acid (PAA), indole-3-butyric acid (IBA)] and synthetic [1-naphthaleneacetic acid (NAA)] auxins on the growth and metabolism of green microalga Chlorella vulgaris was examined. Exogenous auxins acted in a concentration-dependent manner on algal growth. Phytohormones at concentration of 100 μM inhibited algal growth expressed as the number of cells. IAA and IBA displayed the highest biological activity at 0.1 μM, whereas PAA and NAA were characterized by the greatest stimulatory effect on the number of cells at 1 μM. Treatment with IAA and IBA at 0.1 μM or NAA and PAA at 1 μM increased the concentration of photosynthetic pigments, monosaccharides and soluble proteins in C. vulgaris. Moreover, all auxins stimulated enzymatic (ascorbate peroxidase, catalase, superoxide dismutase) and non-enzymatic antioxidant (ascorbate, glutathione) systems in C. vulgaris, and therefore, suppressed lipid peroxidation and hydrogen peroxide accumulation. The data supports the hypothesis that auxins play a central role in the regulation of C. vulgaris growth and metabolism and the components of cellular redox systems that are thought to have a prominent role in the regulation of auxin-dependent processes.