Вilyk Z. Асtive transport of sodium in corn seedling root cells under salt stress condition and influence of synthetic preparation.

The dissertation thesis is devoted to the problem of biochemical mechanisms of plant protection from toxic Na+ which is the major cation causing salinization. It was demonstrated that release Na+ from cytoplasma is provided essentially by vacuolar Na+/H+-antiporters in normal conditions of cultivation. In presence of Na+ activity of vacuolar and plasma membrane Na+/H+-antiporters are increased, especially of plasma membrane Na+/H+-antiporter. It was established that function of plasma membrane Na+/H+-antiporter is supported for significant H+-pump, represented by E-P-type H+-ATP-ase in normal conditions of cultivation and NaCl exposition. In presence of Na+ transport activity of plasma membrane H+-ATP-ase is increased but hydrolytical activity of plasma membrane H+-ATP-ase is decreased. It is existed two H+-pumps in vacuolar membrane represented by H+-PPi-ase and H+-ATP-ase V-type. Role of H+-PPi-ase in created of vacuolar membrane potential is essential highly under normal conditions of cultivation but it is decreased with age of corn seedlings. However in conditions of NaCl exposition, especially 1-day NaCl exposition, transport activity of H+-ATP-ase V-type is increased but transport activity of H+-PPi-ase is decreased. Thus, only H+-ATP-ase V-type is assisted in adaptation cells to salinization, because H+-ATP-ase is provided function of vacuolar Na+/H+-antiporter and H+-pump represented by H+-PPi-ase were not taken part in this process. Comparison of bioactive preparations Methyure (6-methyl-2-mercaptohydroxypyrimidine) and Ivine (N-oxide -2,6 hydroxypyridine) salt-protective abilitities denonstrated the obvious preference of the first one. It was etstablished that its higher effect is based mainly on the more potent Na + removing from cell cytoplasm outside and to a vacuolar space by activation of Na+/H+-antiporters depended from H+-pumps represented with H+-ATPases. A role of Methyure chemical structure for its salt-protective ability was elucidated.