Zh. I. Ribchenko, Т. A. Palladina

Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Kyiv;
e-mail: zhanna_bio@ukr.net, tatiana_palladina@ ukr.net

Participations of electrogenic H⁺-pumps of  plasma and vacuolar membranes represented by E₁-E₂ and V-type H⁺-ATPases in plant cell adaptation to salt stress conditions has been studied by determination of their transport activities. Experiments were carried out on corn seedlings exposed during 1 or 10 days at 0.1 M NaCl. Preparations Methyure and Ivine were used by seed soaking at 10^-7 M. Plasma and vacuolar membrane fractions were isolated from corn seedling roots. In variants without NaCl a hydrolytical activity of plasma membrane H⁺-ATPase was increased with seedling age and its transport one was changed insignificantly, wherease the response of the weaker vacuolar H⁺-ATPase was opposite. NaCl exposition decreased  hydrolytical activities of both H⁺-ATPases and increased their transport ones. These results demonstrated amplification of H⁺-pumps function especially represented by vacuolar H⁺-ATPase. Both preparations, Methyure mainly, caused a further increase of transport activity which was more expressed in NaCl variants. Obtained results showed the important role of these H⁺-pumps in plant adaptation under salt stress conditions realized by energetical maintenance of the secondary active Na⁺/H⁺-antiporters which remove Na⁺ from cytoplasm.