ЭлБиб

M O L ECU LA R B IO LO G Y O F PLAN T C E L L S IN V ITRO

CAPTUREOFTHEEXCESSOFCYTOPLASMICIONSBYVACUOLEOF

ISOLATEDPROTOPLAST

G.A.Velikanov, A.N.Tsentsevitsky, L.P.Belova

Kazan Institute o fBiology, Russian Academy o fSciences Kazan, 420503, BoxN 30.

Patch-registration with loose contact of the glass micropipette with the

surface o f plasmalemma was applied on prelim inarily stabilized in high

potassium medium (130 mM) protoplasts isolated from stem cortex cells o f

Pisum Sativum L.

seedlings. Under the influence of severe hyperpolarization

(» 400 mM) on the local area o f plasmalemma the macroscopic transient

current with fast kinetics (< 5 ms) was registered which causes temporal

excess o f potassium ions in the cytoplasm. Simultaneously with this

transient current voltage alterations in cytoplasm and vacuole was registrated

relative to graund with the aid of microelectrodes and also transtonoplast

current with the aid of the second registering micropipette. It is shown that

during transient current developing on plasmalemma the tonoplast that was

initially in high resistance state (Rton » Rplasm) turns within 1 msec to the

state with high conductance for inward vacuolar current, i.e. rapid capture of

the excess ions of cytoplasm by vacuole takes place.

The discovered phenomenon and also the method by which it was

revealed makes the protoplast

in vitro a

convenient model for study the role

of transtonoplast ion transfer systems in the mechanism of vacuolar (or

tonoplast) control of cytoplasm state. This relates, for example, to such

processes as auxininduced vacuolization of plant cells, operation of stomatal

apparatus o f leafes o rturgor regulation in the cells of higher plants.

The work is supported by grant o f R F F IN 96-04-49599.

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