Botanica Lithuanica , Volume 15, Number 3

2009 m.

The first and essential step of phytohormone indole-3-acetic acid (IAA or auxin) signalling – perception has been investigated by means of biochemical-molecular approaches. The subcellular localization of its perception (recognition and binding) sites, specific auxin binding proteins (ABPs) and peculiarities of ABP macromolecules and IAA ligand interactions in different compartments of kidney bean (Phaseolus vulgaris L.) cells were carried out. The description of basic characteristics of individual IAA-ABP complexes formed in separate subcellular compartments – plasmalemma, chloroplast and mitochondria (EC50, KD, n, specificity, etc.) were presented. These characteristics were compared with those of IAA-ABP1 from plasmalemma, which mediates cell response to IAA by enlargement. For the first time, the obtained results led to predict that the chloroplast may have a potential to take stand in cellular IAA signaling, at least by regulating IAA distribution in cell.

Keywords: auxin binding proteins (ABPs), kidney bean, chloroplast, plasmalemma, mitochondria.

AA (indole-3-acetic acid) signal transduction events taking place during IAA-regulated plant growth processes of gravitropic reaction, division and elongation of cells and plant seedlings with different sensitivity to IAA, were investigated. Test objects – spring wheat (Triticum aestivum L. ‘Selpek’) and thale cress (Arabidopsis thaliana Heynh.) seedlings. Disruption of IAA-dependent lateral polarization processes after pretreatment with inhibitors staurasporine, NaVO3, dideoxyadenosine leads to supposition that MAP (mitogen-activated protein) kinase signaling system participates in IAA growth signal transduction. IAA signal translocation in the form of IAA-protein complexes from plant cell plasmalemma to cell nucleus is shown with peculiarities characteristic for dividing and elongating wheat seedling cells. On the basis of experiments with Arabidopsis thaliana axr 3-1 and axr 4-2 mutants IAA action dependence upon Aux/IAA proteins is discussed.

Keywords: IAA signal transduction, IAA-dependent growth reactions, Triticum aestivum, Arabidopsis thaliana.

Effect of quaternary ammonium salts 3-DEC, 3-DMC, 17-DMC and physiological analogues of auxin TA-12 and TA-14 on winter and spring oilseed rape growth was studied. 3-DEC and 17-DMC compounds retarded the intercalary growth of stems, increased the resistance towards lodging of rape stems, activated the formation of productivity elements and enhanced the yield quality. The compounds TA-12 and TA-14 stimulated the differentiation of winter oilseed rape vegetative cone, predetermined early formation of individual flower organs, enhanced embryo formation.

Keywords: rape, retardants analogues, auxin analogues, embryogenesis, productivity.

This article is focused on gravity and light effects on growth and bending of laminas as well as unfolding and morphology of petioles of garden cress (Lepidium sativum L.) leaves. Experiments were performed in conditions of normal and altered by fast clinorotation (50-rpm) gravity, in red (660 nm) and far-red (735 nm) light or in the dark. Clinorotation retarded unfolding of leaves in the dark, whereas the applied light suppressed disorientation of leaves on the clinostat. We identified sedimenting amyloplasts in endodermic cells which were located in the proximal region of L. sativum petioles. The obtained data imply that red and far-red light, even in altered gravity, is an essential factor for the directional growth of leaves.

Keywords: clinostat, directional growth, Lepidium sativum, gravity, leaves, light spectrum, tropism.

In this study, the kinetics of gravity-dependent motion of amyloplasts-statoliths along endodermal cells has been for the first time analyzed in order to testify an involvement of cytoskeleton in gravisensing of garden cress (Lepidium sativum L.) hypocotyls. After growth at 1 g and in weightlessness mimicked by fast clinorotation, gravitropic stimulation for 24 min was applied by exposition of the hypocotyls to weightlessness or 180° inversion and to the gravity action in basal or apical direction. In endodermal cells of 1-g hypocotyls, a significant distally-directed shift of amyloplasts from the basal part was determined after the 6-min period of weightlessness and after the first minute of inversion. In hypocotyls grown in weightlessness, already after the first minute of stimulation the essential statoliths movement along the direction of gravity was evaluated. It is supposed that the positioning of amyloplasts along statocytes of 1-g hypocotyls is controlled by the gravity and opposite intracellular forces from cytoskeleton, impact modulating the plastid motion of which becomes evident under altered gravity conditions.

Keywords: Lepidium sativum, gravity, amyloplast, cytoskeleton, endodermis, hypocotyls.

nterspecific hybridization of Lilium allows to investigate mechanisms of reproduction isolation barriers. To overcome fertilization barriers in incongruous crosses, cut style pollination and pollination of native style by mixed pollen were performed. Cut style pollination allowed overcoming pre fertilization barriers only in cases when cultivars from division Asiatic hybrids were pollinated by Lilium pumilum DC. and L. concolor Salisb. Crossing of Asiatic hybrids as females with L. monadelphum M. Bieb., L. regale E. H. Wilson and L. candidum L. or crossing L. martagon L. with Trumpet hybrids and Oriental hybrids were successful when mixed pollen of incongruous species were used for pollination. Inheritance of species specific molecular markers allowed screen progeny of Asiatic hybrids crossed with L. candidum and Asiatic hybrids crossed with L. regale. It was found that hybrids resulted from crossing Asiatic hybrids with L. concolor were male and female fertile while hybrids between Asiatic hybrids and L. pumilum were only male fertile.

Keywords: Lilium, interspecific hybridization, reproductive isolation, inheritance.

Effect of ultraviolet A (UV-A) radiation on Crepis capillaris (L.) Wallr. plants was investigated. The UV-A (365 nm) doses were 0, 2, 4, 6, 8, 10 kJ·m-²·d-¹. The duration of radiation was 7 days. Effects of UV-A radiation on fresh and dry biomass, leaf area and quantities of plant pigments (chlorophylls a and b, carotenoids) was determined. Superoxide dismutase (SOD) activity in leaves was estimated by native 10 % polyacrylamide gel electrophoresis (PAGE) method. The obtained results demonstrated harmful effect of UV-A radiation on the growth of plant: as little as 4 kJ·m-²·d-¹ UV-A reduces fresh and dry biomass of C. capillaris, the amount of chlorophylls a and b as well as carotenoids. Only higher doses of UV-A had negative effect on the leaf area. UV-A dose of 8 kJ·m-2 induces a new isoform of SOD. This induction should be evaluated as a response to UV-A irradiation. It shows SOD involvement in the mechanism of antioxidant protection.

Keywords: ultraviolet A, irradiation, Crepis capillaris, leaf pigments, superoxide dismutase.

Lithuanian fruit and berries yeast populations (picked up during 2006–2008 years) were used for the determination of killer strains occurrence. It was found that 33 % of killer toxin-producing strains, distributed in Lithuania, belong to the Saccharomyces genus. According to killing and immunity tests it was determined that K2 type killers (95 %), but not K1 and K28 predominate in S. cerevisiae killer yeast population. In addition, new killer strains Kx and KN1x were isolated and investigated. Wide activity of secreted toxins at different acidic pH values was demonstrated.

Keywords: Saccharomyces cerevisiae, killer toxin, immunity, berries, Lithuania.

n 2007–2009 from 230 spontaneous fruit, berries and algae fermentations two yeast K+, K- and 5 bacterial strains, possessing special adhesive, fungicidic and fungistatic properties, were isolated. It was determined that killer yeast strains secrete adhesive substances at 42 °C temperature, while bacteria – at 20 °C. From spontaneous grapes, pigeon-berries and honeysuckle fermentations bacterial strains 1J-10, 5J-21, 6J34, forming colony of liquid consistency and producing adhesives attractive for glue production, were isolated. It was revealed that bacterial strains Tx, Tx-K1 and Tx054 produce killer factors inhibiting growth of some phytopathogens and micromycetes. Possibility to apply the mentioned bacteria in production of biopreparates was proposed.