[Activation of extracellular peroxidase of wheat roots under the action of xenobiotics].

We studied the influence of xenobiotics of various chemical natures, including N,N'-dicyclohexylcarbodiimide, diethylstilbestrol, and chlorpromazine, on the activity of peroxidase, a redox-enzyme that participates in defense reactions of plants. It was shown that the influence of the studied xenobiotics on severed roots of wheat seedlings caused an increase in the permeability ofplasmalemma for K+ and H+ and stimulated the activity of the extracellular peroxidase that forms the superoxide radical anion. It is assumed that the extracellular peroxidase can initiate the transformation of alien compounds on the cell surface, before their entrance into the cells.

[Mitotic index of meristematic cells and root growth of Pisum sativum is affected by inositol cycle modulators].

Relationships between cell division and inositol cycle modulation caused by different effectors in roots of Pisum sativum were studied. Stimulation of the inositol cycle by myoinositol increased the mitotic index of meristematic cells and root length, while the inhibition of the cycle with Li+ and a heavy metal Gd3+ considerably decreased mitotic activity and growth. Exposure of roots to 10 mM CaCl2 and 15 mM myoinositol resulted in the accumulation of chromosome aberrations. Changes in the activity of inositol cycle are assumed to be involved in the root growth control.

[Cell surface peroxidase--generator of superoxide anion in wheat root cells under wound stress]. / Peroksidaza kletochnoi poverkhnosti--generator superoksid-aniona v kornevykh kletkakh pshenitsy pri ranevom stresse.

Development of wound stress in excised wheat roots is known to be accompanied with an increase in reactive oxygen species (ROS) production, fall of membrane potential, release of K+ from cells, alkalization of extracellular solution, changes in respiration and metabolism of structural lipids. Dynamics of superoxide release correlates with changes in other physiological parameters, indicating the cross-reaction of these processes. Activity of peroxidase in extracellular solution after a 1 h incubation and removal of roots was shown to be stimulated by the range of organic acids, detergents, metals, and to be inhibited by cyanide. Superoxide production was sensitive to the addition of Mn2+ and H2O2. Increase in superoxide production correlates with the enhancement of peroxidase activity at the application of organic acids and detergents. The results obtained indicate that cell surface peroxidase is one of the main generators of superoxide in wounded wheat root cells. Different ways of stimulation of the ROS producing activity in root cells is supposed. By controlling superoxide and hydrogen peroxide formation, the cell surface peroxidase can control the adaptation processes in stressed plant cells.