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

The function of two electrogenic H⁺-pumps in plant vacuolar membrane (tonoplast) and their response to the salt stress conditions and adaptogenic preparations have been studied. Experiments were carried out on tonoplast fraction isolated from the roots of corn seedlings grown in water culture which were exposed at 7-day age in the presence of 0.1 M NaCl during 1 or 10 days. The role of every H⁺-pump in potential generation was elucidated by assaying transport and hydrolytic activity of enzymes – V-type H⁺-ATPase and H⁺-pyrophosphatase represented their mechanisms. It was found in the control variant that transport activity H⁺-PPase exceeded considerably H+-ATPase one in the tonoplast from 7-day seedlings. However this situation was changed in 18-day seedlings by H⁺-ATPase transport activity increasing with age whereas its hydrolytic one was decreased. Both NaCl expositions caused the progressive decrease of transport and hydrolytic activity of H⁺-PPase whereas Н⁺-ATPase responded to this factor by increasing transport activity, while its hydrolytic one fell. Bioactive preparations Methyure and Ivine (10^-7 М) used by seed soaking caused a further increase of H⁺-ATPse transport activity especially in the presence of NaCl whereas H⁺-PPase one was not changed. Methyure effect in these experiments was more pronounced. Obtained results demonstrated participation of tonoplast H⁺-pumps in plant adaptation to NaCl which can be realized by amplification of Na⁺-H⁺ antiporter energization. An important role of vacuolar H⁺-ATPase in growth and adaptation processes in plants has been proved.

Keywords: Ivine, Methyure, tonoplast, transport and hydrolytic activities of H(+)-ATPase and H(+)-PPase