Planta
Abstract. To investigate the effect of water stress on carbon metabolism in growing potato tubers (Solanum tuberosum L.), freshly cut and washed discs were incubated in a range of mannitol concentrations corresponding to external water potential between 0 and 1.2 MPa. (i) Incorporation of [14C]glucose into starch was inhibited in water-stressed discs, and labeling of sucrose was increased. High glucose...
Abstract. Five major soluble nuclear proteins associated with cell proliferation were identified in Allium cepa L. root cells. One of them, of 64kDa, was revealed by Western blotting with anti-mammalian nucleolin antibodies. A polyclonal antibody raised against this protein, which we have named NopA64, localised it in the nucleolus as well as in nuclear coiled bodies. Together with NopA64, the antibody...
Abstract. Plant regeneration via somatic embryogenesis was achieved from leaf petioles of Pelargonium sp. `Frensham cultured on Murashige and Skoog medium containing 15 M N6-benzyladenine, and 5 M -naphthaleneacetic acid (NAA). More than 80% of these somatic embryos converted into plants when isolated and cultured on Murashige and Skoog medium supplemented with 15 M NAA. Stable transgenic plants were...
Abstract. Whole-cell patch-clamp techniques were used to measure anion currents through the plasma membrane of protoplasts of mesophyll cells of expanding pea (Pisum sativum L.) leaves. Voltage-induced changes of the currents could be modelled with single exponential activation and deactivation kinetics. The anion currents were activated at negative membrane potentials. The time constant of activation,...
Abstract. Jasmonic acid (JA) is thought to be part of a signal-transduction pathway which dramatically increases de-novo nicotine synthesis in the roots and increases whole-plant (WP) nicotine pools in response to the wounding of the leaves in Nicotiana sylvestrisSpegazzini and Comes (Solanaceae). We report the synthesis of a doubly labeled JA ([1, 2-13C]JA) and use it as an internal standard to quantify...
Abstract. Light-stress-related changes in photosystem I (PS I) were analyzed in photoautotrophic cultured cells of Marchantia polymorpha L. High light treatment (30h; 1300 mol photonsm2s1) reduced the PS I-mediated electron-transport rate by more than 50% and the photochemical efficiency of photosystem II (PS II) by about 35%. In photoinhibited cells, 76% of the PS II centers remained closed in low...
Abstract. A soybean cytosolic glutamine synthetase gene (GS15) was fused with the constitutive 35S cauliflower mosaic virus (CaMV) promoter in order to direct overexpression in Lotus corniculatus L. plants. Following transformation with Agrobacterium rhizogenes, eight independent Lotus transformants were obtained which synthesized additional cytosolic glutamine synthetase (GS) in the shoots. To eliminate...
Abstract. Gibberellins A1 and A3 are the major physiologically active gibberellins (GAs) present in young fruit of pea (Pisum sativum L.). The relative importance of these GAs in controlling fruit growth and their biosynthetic origins were investigated in cv. Alaska. In addition, the non-13-hydroxylated active GAs, GA4 and GA7, were identified for the first time in young seeds harvested 4d after anthesis,...
Abstract. The removal of Ca2+ from the medium by intact vacuoles and microsomes of Chenopodium album was investigated by measuring INDO-1 fluorescence emission at 400 and 480 nm and the response of Ca2+ -selective mini-electrodes. The removal of Ca2+ depended on the presence of MgATP, displaying an apparent KmATP of about 50 M, a KmCa of 400500 nM, and a nucleotide specificity (%) of ATP (100)CTP...
Abstract.The temperature dependence of metabolic rates determines how plant growth rates vary with temperature. This paper shows that equations on physiological relations between respiration rates (i.e. rates of heat loss and CO2 evolution) and growth rates can be used to describe temperature effects on plant growth rate. Incorporating measured values of plant respiratory heat and CO2 rates at a few...
Abstract. Open-flow assays of H2 evolution in Ar:O2 (80:20, v/v) by nodulated roots were performed in situ with soybean [Glycine max (L.) Merr.] and alfalfa [Medicago sativa L.) grown in sand with orthophosphate (Pi) nutrition either limiting (low-P) or non-limiting (control) for plant growth. Nodule growth was more limited than shoot growth by P deficiency. Phosphorus concentration was less affected...
Abstract. 3-Hydroxybenzoate:coenzyme A ligase, an enzyme involved in xanthone biosynthesis, was detected in cell-free extracts from cultured cells of Centaurium erythraea Rafn. The enzyme was separated from 4-coumarate:coenzyme A ligase by fractionated ammonium sulphate precipitation and hydrophobic interaction chromatography. The CoA ligases exhibited different substrate specificities. 3-Hydroxybenzoate:coenzyme...
Abstract. As an attempt to examine the transcripts expressed in a single cell type and to unveil the physiology of guard cells at the molecular level, we generated 515 expressed sequence tags (ESTs) from a directional cDNA library constructed from guard-cell protoplasts of Brassica campestris L. ssp. pekinensis. A comparative analysis of the guard-cell ESTs against the National Center for Biotechnological...
Abstract. The effects of a number of treatments, both in planta and in vitro, on the accumulation of mRNA encoding dehydrin, an abscisic acid (ABA)-inducible protein, were determined for guard cells and mesophyll cells prepared from leaves of the Argenteum mutant of Pisum sativum L. Guard cells and mesophyll cells treated for 10d with ABA in planta accumulated dehydrin mRNA. However, after 1 or 3d...
Abstract. A new class of recessive Arabidopsis mutants, designated cristal (cri) has been isolated which display several abnormalities reminiscent of hyperhydric symptoms. These characteristics include translucent and wrinkled cotyledons and leaves, abnormal chloroplast organization, a reduced amount of chlorophyll, a reduced dry weight and a decreased number of palisade cells in the leaves accompanied...
Abstract. Potato (Solanum tuberosum cv. Dsire) plants expressing yeast invertase directed either to the apoplast, vacuole or cytosol were biochemically and physiologically characterised. All lines of transgenic plants showed similarities to plants growing under water stress. Transformants were retarded in growth, and accumulated hexoses and amino acids, especially proline, to levels up to 40-fold...
Abstract. Submerged aquatic higher plants maintain acropetal water transport to the young leaves in active growth to satisfy their demand for nutrients and hormones derived from the roots. We here present the first measurements of hydraulic properties for a submerged plant, the monocotyledon Sparganium emersum Rehman. The hydraulic conductance per unit length, Kh, was measured in leaf segments without...
Abstract. Similar to heat-stress transcription factors (HSFs) from non-plant sources, HSFA1 and HSFA2 from tomato (Lycopersicon esculentum Mill) contain two conserved clusters of basic amino acid residues (K/R1 and K/R2) which might serve as nuclear localization signal (NLS) motifs. Mutation of either one of them and functional testing of the corresponding proteins in a transient expression assay...
Abstract. Potassium antimonate was used to localize Ca2+ in tobacco ovules from 0 to 7d after anthesis in pollinated and emasculated flowers. Antimonate binds loosely bound Ca2+ into calcium antimonate; less-soluble forms are unavailable and free calcium usually escapes. Ovules are immature at anthesis. Abundant calcium precipitates in nucellar cells surrounding the micropylar canal. A difference...
Abstract. In the course of a study on the early events of cambial derivative differentiation in Populuseuramericana, seasonal changes in the pattern of pectin methylesterase (PME, EC 3.1.1.11) isoforms were followed. During the resting season, cell wall extracts contained mainly alkaline isoforms with an Mr around 55kDa and optimal pH between 5.6 and 6.0. Neutral isoforms with an Mr around 35kDa and...