Activity of catalase and superoxidedismutase in leaves of halophyte plants under the tidal dynamics of the White Sea

Activity of catalase (CAT) and superoxide dismutase (SOD) enzymes in the leaves of halophyte plants Triglochin maritima L., Plantago maritima L., Tripolium vulgare Bess. ex Nees and Zostera marina L. was investigated in a 2-year field experiment carried out in the community of the middle littoral marsh on the Pomor (western) coast of the White Sea (Belomorsk region, Russia). The community Tripolium vulgare–Bolboschoenus maritimus–Triglochin maritima–Plantago maritima, was investigated during the tidal cycle. The plants grew under conditions of seawater pollution with high concentration of nitrates (43.68 mgl-1), iron (0.15 mgl-1), nickel (0.15 mgl-1) and lead (0.024 mgl-1). The total projective cover of species in the plant community reached 50% for T. vulgare, and 20% for other dominant species. A direct positive correlation was found between the activity of CAT and SOD in halophyte leaves (r = 0.51–0.68). This research revealed the species specificity of the enzyme activity level in Z. marina. The activity of CAT and SOD in its leaves was significantly lower (0.16±0.06 µmol H2O2/µg of protein; 2.61±0.08 c.u./mg of protein, respectively), than in other species. The maximum values of CAT activity were found in T. vulgare and T. maritima (0.23–0.26 μmol H2O2/μg of protein), and SOD in T. vulgare 4.65 ± 1.12 c.u./mg of protein. The activity of CAT in plant leaves varied over a wide range (1.14–11.83 c.u./mg of protein) and did not depend on the tidal dynamics of the sea. In halophyte leaves, the regulation of plant redox metabolism under hypoxic conditions during flooding is supported by an increase in SOD activity, on average 1.98–2.95 at low tide and 4.12±6.73 c.u./mg of protein at high tide.