The article analyses founding, formation and development of the Laboratory of Plant Physiology of the Institute of Botany in the background of the most significant plant physiology investigations in Lithuania. Principal scientific research trends developed at the laboratory are discussed. Contribution of the researchers to general development of plant growth physiology is revealed.

Keywords: plant physiology, plant growth, gravitropic reaction, physiologically active compounds, history of science, Lithuania.

The transfer of indole-3-acetic acid (IAA) between both IAA synthesizing compartments of the cell – cytoplasm and chloroplast (influx into chloroplasts from cytoplasm and efflux from chloroplasts into cytoplasm) was educed by employing model systems. From the obtained results the presumption on IAA interaction with proteins IAA-transporters another than pin-formed (PINs) or auxin permease (AUX1) in chloroplast membrane was formulated. The suggestion on the possibility of IAA metabolism occurring in this cell compartment was done. The possible role of IAA and auxin-binding proteins (ABPs) complexes formed in chloroplast was discussed.

Keywords: chloroplast, IAA, auxin-binding proteins (ABPs), IAA-ABP complexes.

Two distinct objects, regarding different approaches of the issues in question, were used: baker yeast (Saccharomyces cerevisiae), characterized by a generally acknowledged Ras/PKA signal transduction pathway, and wheat coleoptiles with a well expressed IAA regulatory function. The sum of the obtained results shows that cAMP level controlled signal pathway could be used for IAA signal transduction to the nucleus.

Keywords: IAA signal transduction, cAMP, Saccharomyces cerevisiae, Triticum aestivum.

Effect of the physiological analogues of auxin – original compounds TA-12 (calcium 4-(2-chloro-ethoxycarbonylmethyl)-1-naphthalenesulfonate) and TA-14 (-trialkylammonioalkyl ester of 1-napthylethanoic acid) – on oilseed rape (Brassica napus L.) ‘Casino’ autumn growth peculiarities, cold acclimation-preparation for wintering and reproductivity organs formation was studied. Plants were treated with water solutions of the compounds TA-12 (2 mM identic 417 g ha-1) and TA-14 (4 mM identic 369 g ha-1) at the stage of 4–5 unfolded leaves. The results of field experiments showed positive effect of the compounds TA-12 and TA-14 on oilseed rape cold acclimation and preparation for wintering: they influenced formation of leaf rosette, intensified monosaccharide accumulation in root collum, conversion of the rape cone vegetative phase into a generative one and improved winterhardness of this culture. In spring the number of perished plants in test variants was lower by 11–15 % than in the control. The monitoring of reproductive organs formation showed that under the effect of TA-12 and TA-14, flowering and siliquae formation started 3–4 days earlier. Thus, the physiological analogues of auxin uncovered a possibility to improve preparation of plants for wintering, accelerate and partly unify duration of oilseed rape flowering, siliquae and seeds formation, which determines simultaneous seed maturity as well as formation of more plentiful yield.

Keywords: auxin physiological analogues TA-12, TA-14, oilseed rape, reproductive organs.

The principal aim of the work is to determine possibilities of using a model system that in vitro registers changes in membrane functional activity as a toxicity biomarker of water media. Functional activity was evaluated according to the proton pump (K+, Mg2+-ATPase) activity of Nitellopsis obtusa cell membrane structures. 50 % inhibition of K+, Mg2+-ATPase activity (IC50) was measured in membrane preparations and sensitivity of both freshly isolated and frozen microsome fractions for xenobiotics was investigated. Sensitivity of frozen (-8 oC) microsomal fraction (49±17 μM, n=8) did not significantly (p=0.05) differ from that of freshly isolated one (37±31 μM, n=12), as confirmed by a reference procedure with CuSO4. Sensitivity of frozen microsomal fraction did not change while stored in a fridge for at least 40 days, moreover, the variability of the ATPase activity inhibition endpoint values was less in relation to freshly isolated microsomal fraction. Applying the above-described model systems (H+-ATPase inhibition and electrophysiological characteristics), toxicity of water media under different conditions and at different distances from pollution sources was evaluated in the environment.

Keywords: plasmalemma, phytotoxicity, Nitellopsis obtusa, heavy metals, K+, Mg2+-ATPase activity.

The effect of original compounds 3-DEC (diethylammonio chloride derivative) and 17-DMC (dimethylmorpholinio chloride derivative) on stem growth structure and productivity of winter oilseed rape ‘Kasimir F1’, and on phytohormone content in stem tissues was studied. It was determined that the processes of growth and morphogenesis of rape plants could be controlled applying compounds 3-DEC and 17-DMC of quaternary ammonium salts, which, acting on the phytohormone balance, inhibit the linear growth of stems, induce the formation of mechanical tissues in lower layers of stem. When the optimum structure of stem is formed, the resistance of rape stems to lodging increases, the formation of productivity elements activates, thus stable and high quality yield is obtained.

Keywords: winter oilseed rape, spring oilseed turnip, 3-DEC, 17-DMC, phytohormones.

Dependence of Lepidium sativum L. root and hypocotyl growth and cytological changes in root gravisensors (statocytes) was investigated under unidirectional illumination with blue (450 nm) and red (660 nm) light when the pathway of the induction of gravitropic reaction was eliminated by a horizontal clinostat (HC) rotating at 3 rpm. Roots or hypocotyls were illuminated either from below or above, respectively. Suppression of root growth caused by illumination with blue light came up to 35.4 % because of clinorotation. The effect of red light on root growth in simulated weightlessness was not so obvious. However, bending of roots stimulated by light at 1 g increased on HC. Meanwhile, blue light diminished the curvature of hypocotyls grown on HC from 28.5ŗ to 11.0ŗ. The orientation of hypocotyls, changed by suppression of gravitropism, was restored by blue illumination induced phototropism. Illumination of roots invoked changes in the elongation of gravisensors. An increase in the area of statocytes, mainly caused by cell elongation in blue light, was determined. Blue light, applied in HC-simulated weightlessness, increased the number of amyloplasts in the statocytes from the 3rd to 5th columella rows more significantly as compared with analogous cells at 1 g. Illumination diminished the amyloplast size in the statocytes of 5–6 columella rows. The data imply that changes in orientation of Lepidium sativum hypocotyls and in morphology of gravisensors of roots that were more pronounced under the action of blue light correlate with gravitropism suppression in weightlessness.

Keywords: gravity, light, weightlessness, horizontal clinostat, Lepidium sativum, statocyte, amyloplast.

This paper deals with a relation between the parameters of gravity force and amyloplasts (statoliths) positioning along statocytes in garden cress (Lepidium sativum L.) roots after growth at 1g and in weightlessness simulated by fast clinorotation. Gravitropic stimulation for 6 min was applied by transferring the former roots to weightlessness or 180° inversion and by the action of 1 g in distal and proximal direction of the second roots. After 2 min of both 1-g root treatments, the significant shift of statoliths from the initial distal part of statocytes in proximal direction was determined. Later on, this proximal displacement slowed down in weightlessness, but proceeded under inversion. In roots, grown on clinostat, the movement of amyloplasts away from the initial central position was similar in the distal as well as in proximal direction within 2-min period of 1-g stimulation. After 4 min, the statoliths started moving more rapidly to the proximal cell wall as compared to the distal. It is concluded that statolith motion along the 1-g root statocyte is controlled by force of gravity, however, the intracellular forces, first of all cytoskeleton-mediated forces, are manifested strongly within the first 2-min period of altered gravity.

Keywords: gravity, amyloplast, cytoskeleton, statocyte, root, garden cress.