Metabolism of l-Threonic Acid in Rumex x acutus L. and Pelargonium crispum (L.) L'Hér

l-Threonic acid is a natural constituent in leaves of Pelargonium crispum (L.) L'Hér (lemon geranium) and Rumex x acutus L. (sorrel). In both species, l-[(14)C]threonate is formed after feeding l-[U-(14)C]ascorbic acid to detached leaves. R. acutus leaves labeled with l-[4-(3)H]- or l-[6-(3)H]ascorbic acid produce l-[(3)H]threonate, in the first case internally labeled and in the second case confined to the hydroxymethyl group. These results are consistent with the formation of l-threonate from carbons three through six of l-ascorbic acid. Detached leaves of P. crispum oxidize l-[U-(14)C] threonate to l-[(14)C]tartrate whereas leaves of R. acutus produce negligible tartrate and the bulk of the (14)C appears in (14)CO(2), [(14)C]sucrose, and other products of carbohydrate metabolism. R. acutus leaves that are labeled with l-[U-(14)C]threonate release (14)CO(2) at linear rate until a limiting value of 25% of the total [U-(14)C]threonate is metabolized. A small quantity of [(14)C]glycerate is also produced which suggests a process involving decarboxylation of l-[U-(14)C]threonate.     

LC–MS quantification of parthenolide and cholinesterase inhibitory potential of selected Tanacetum L. (Emend. Briq.) taxa

The acetonitrile extracts of various Tanacetum L. (Emend. Briq.) taxa from Turkey as well as parthenolide, a sesquiterpene lactone found in Tanacetum species as active substance were investigated for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in pathogenesis of Alzheimer's disease, at 100 μg mL⁻¹ using ELISA microplate assay. Most of the extracts displayed a remarkable AChE inhibition where the leaf of Tanacetum argenteum subsp. flabellifolium had the highest inhibition (96.68 ± 0.35%). The extracts had moderate inhibition toward BChE, among which the stem of Tanacetum argyrophyllum var. argyrophyllum-1 exerted the best inhibition (63.81 ± 3.64%). However, parthenolide exhibited low inhibition against both of the enzymes. Total flavonoid content of the extracts was determined spectrophotometrically. Parthenolide, a sesquiterpene lactone, was quantified in these taxa by LC–MS and the leaf of T. argenteum subsp. argenteum possessed the richest parthenolide amount (2.261 ± 0.002%), while most of the species screened were found to contain the required percentage (0.2% minimum) by European Pharmacopeia.     

Volatile constituents of Erodium cicutarium (L.) L’ Hérit. (Geraniaceae)

Essential oils from Erodium cicutarium were obtained by hydrodistillation (samples consisting of entire plants (ec1), leaves and stems (ec2)) and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS), resulting in a total of 177 components being identified. The essential oils were of a very similar chemical composition and consisted mainly of aliphatic compounds and their derivatives. Fatty acids and fatty acid derived compounds were the most common, 51.3% (ec1) and 60.1% (ec2), followed by carotenoid derived compounds, 12.6% (ec1) and 20.2% (ec2), and then terpenoids, 14.9% (ec1) and 14.2% (ec2). The main constituents in the oils were hexadecanoic acid, 22.8% (ec2) and 35.9% (ec1) and hexahydrofarnesyl acetone, 10.8% (ec2) and 11.6% (ec1). The results obtained differ markedly from those previously reported for the same species.     

Transformation of elite white poplar (Populus alba L.) cv. ' Villafranca' and evaluation of herbicide resistance

 Transgenic white poplar plants (Populus alba L.) expressing the nptII gene and the bar gene from Streptomyces hygroscopicus have been produced using Agrobacterium tumefaciens-mediated gene transfer. Eleven kanamycin-resistant plant lines were obtained with a transformation frequency of 7%. Successful genetic transformation was confirmed by Southern and northern analyses. The level of resistance to the commercial preparation of phosphinothricin (Basta; Roussel-Hoechst Agrovet) was evaluated by in vitro and in vivo assays. Using in vitro selective conditions for phosphinothricin, only plantlets from four kanamycin-resistant independent lines remained green and continued to grow and root. After transfer to the growth chamber, all selected transgenic lines were shown to be completely resistant to the herbicide Basta with doses equivalent to 6 l ha^–1 (normal field dosage) and were tolerant at concentration of 12 l ha^–1. This is the first report describing the genetic transformation of a P. alba clonal cultivar of commercial interest with a gene of agronomic value. Received: 12 June 1999 / Revision received: 6 March 2000 / Accepted: 7 March 2000     

Chiasma frequency variation inCepaea hortensis (Müll.) and a comparison withC. nemoralis (L.)

Chiasma frequency variation has been studied in 12 populations ofCepaea hortensis and the results compared with those previously obtained forC. nemoralis from the same populations. Variation in chiasma frequency is effectively restricted to a single large bivalent. In both species there are significant differences between populations in chiasma frequency. Although mean population mean chiasma frequencies are similar inC. hortensis andC. nemoralis, C. hortensis is less variable thanC. nemoralis. This can be seen, to a greater or lesser extent, at several levels-(i) within cells, (ii) between cells, (iii) between snails, and (iv) between populations-and is most noticeable when interstitial chiasmata are considered separately from terminal chiasmata. Data from 6 populations suggest that chiasma frequency remains stable between successive years. It is suggested that, since sympatric populations were studied, the most likely explanation for differences in chiasma frequency statistics between the two species is thatC. hortensis andC. nemoralis are responding differently to similar selective pressures.     

Ultrastructural characteristics of « Diplotaxis erucoides (L.) DC. » suspensor

Abstract

The development and general morphology of Diplotaxis erucoides (L.) DC. suspensor is of the « Onagrad Type », « Alyssum Variation ». Maximum growth of the suspensor occurs from the globular to the early heart stage of embryo development. The suspensor starts then to degenerate disintegrating shortly after the torpedo stage of the embryo.

The wall ingrowths of the long, tapering, basal cell are especially abundant at the cell's micropilar pole which is closely surrounded by well developed wall ingrowths formed by the endosperm. Wall ingrowths and plasmodesmata are present on the suspensor cells cross walls with the exception of the cell closest to the embryo. No such structures in fact are present on the walls separating this last cell both from the embryo and from the rest of the suspensor. Wall ingrowths are generally associated with numerous, large, mitochondria.

The morphological data seem to indicate that absorption and transport of nutrients from the surrounding tissues is a main function of the suspensor. The possibility of an elaborative and secretory function of this structure is discussed.     

Micropropagation of sour cherry (Prunus cerasus L.) cv. Šumadinka

Sour cherry cv. umadinka (Prunus cerasus L.) is the leading Yugoslav cultivar for production orchards. A method of micropropagation has been developed for the purpose of growing umadinka on its own roots and for rapid multiplication.Aseptic cultures were initiated from shoot explants 1–2 mm long on Murashige & Skoog medium with (in mgl^-1) 6-benzylaminopurine (BAP): 1, indole-3-yl butyric acid (IBA): 1 and gibberellic acid (GA₃): 0–1.The best medium for proliferation was MS with (in mgl^-1): BAP 0.5, IBA 0.1, GA₃ 0.1, but media with (in mgl^-1): BAP 0.5, NAA 0.1, GA₃ 0.1 and BAP 1, NAA 0.1 and GA₃ 0.1 were also shown to be good. A higher degree of proliferation obtained with some media did not necessarily result in a better quality of plantlets produced.For rooting the best combination of culture medium was achieved with pretreatment 10 days in MS 1/2 with 1 mgl^-1 IBA, followed by transfer to a hormone-free medium after 5–10 days, resulting in 88% success.The rooted plants were planted in containers and acclimatized under mist, with over 90% of plants surviving transplantation.     

Effects of drought stress on the evergreen Quercus ilex L., the deciduous Q. robur L. and their hybrid Q. × turneri Willd.

Five-year-old trees of deciduous Quercus robur L., evergreen Q. ilex L., and their semideciduous hybrid, Q. × turneri Willd. (var. pseudoturneri), growing in pots, were subjected to drought stress by withholding water for 18–22 days, until leaf water potentials decreased below ?2 MPa. Gas-exchange rates, oxygen evolution, and modulated chlorophyll (Chl) fluorescence measurements revealed that by strong stomata closure and declining photosynthetic capacity down to approximately 50%, all three taxa responded with strongly reduced photosynthesis rates. In Q. robur, photochemical quenching of the drought-stressed plants was much lower than in nonstressed controls. Dissection of the occurring events in the photosynthetic electron transport chain by fast Chl fluorescence induction analysis with the JIP-test were discussed.     

The effects of external potassium and magnesium concentrations on the magnesium and potassium inflow rates and growth of micropropagated cherry rootstocks, “F.12/1” (Prunus avium L.) and “Colt” (Prunus avium L.) × Prunus pseudocerasus L.)

The effects (and interaction) of two solution concentrations of Mg (50, 500, μM) and two of K (250, 4250 μM) on the growth of micropropagated plants of “F. 12/1” and “Colt” were investigated using a flowing solution culture system. Magnesium inflow and growth of “Colt” and “F. 12/1” were inhibited to a similar extent by an increased concentration of K in the nutrient solution. However, the consequences of this inhibition were different. Reduced inflow of Mg in “F. 12/1” caused Mg deficiency symptoms at high and low concentrations of K, whereas this only occurred with a combination of high K concentration and low Mg concentration in “Colt”. The distribution of dry matter within the plant was significant in determining susceptibility to Mg deficiency. Since “F. 12/1” has a smaller root:shoot ratio than Colt it is unable to sustain the same concentration of Mg in leaves as “Colt” irrespective of external K concentration. The molar ratio of K:Mg in soil solutions should remain <8.5:1 in order to ensure maximum growth of “F. 12/1” and “Colt”. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biomass and primary production of Cladophora glomerata (L.) Kütz. in the Neva Estuary

The dynamics of the biomass, primary production, and P/B ratio of floating and attached forms of green filamentous alga Cladophora glomerata (L.) Kütz. was studied for the shallow water littoral area of the Neva Estuary in 2003–2006. The biomass of the floating algae constituted up to 70% of the total biomass, and the primary production reached up to 90% of the total for the depths of 0–1 m from the middle of July to the end of August.     

The chromosome morphology ofArabidopsis thaliana (L.)Heynh. and some remarks on the problem ofHylandra suecica (Fr.) Löve

The chromosome number ofA. thaliana from three localities in Central Bohemia was found to be 2n=10. All the chromosomes (length 1,5–2,6μm) belong to the atelocentric type, four pairs (m) having the centromere in the median and one pair (sm) in the submedian region. In connection with the discussion on the origin ofH. suecica the author presents the following preliminary results: a) the failure to cross the tetraploidCardaminopsis arenosa (L.)Hayek withA. thaliana; b) the successful crossing of the diploidC. petraea (L.)Hiit. withA. thaliana; c) the discovery of a diploid population ofC. arenosa (2n=16) in the Tatra Mts. (Czechoslovakia).     

Two Genes (ClS1 and ClF-box) Involved the Self-Incompatibility of ”Xiangshui” Lemon (Citrus limon (L.) Burm. f.)

Plant Molecular Biology Reporter - Gametophytic self-incompatibility (GSI) is an important factor affecting fruit development and is one of the important mechanisms of seedlessness in citrus....     

Molecular evolution of glycinin and β-conglycinin gene families in soybean (Glycine max L. Merr.)

There are two main classes of multi-subunit seed storage proteins, glycinin (11S) and β-conglycinin (7S), which account for approximately 70% of the total protein in a typical soybean seed. The subunits of these two protein classes are encoded by a number of genes. The genomic organization of these genes follows a complex evolutionary history. This research was designed to describe the origin and maintenance of genes in each of these gene families by analyzing the synteny, phylogenies, selection pressure and duplications of the genes in each gene family. The ancestral glycinin gene initially experienced a tandem duplication event; then, the genome underwent two subsequent rounds of whole-genome duplication, thereby resulting in duplication of the glycinin genes, and finally a tandem duplication likely gave rise to the Gy1 and Gy2 genes. The β-conglycinin genes primarily originated through the more recent whole-genome duplication and several tandem duplications. Purifying selection has had a key role in the maintenance of genes in both gene families. In addition, positive selection in the glycinin genes and a large deletion in a β-conglycinin exon contribute to the diversity of the duplicate genes. In summary, our results suggest that the duplicated genes in both gene families prefer to retain similar function throughout evolution and therefore may contribute to phenotypic robustness.     

Emission of hydrogen sulfide by twigs of coniferes — acomparison of Norway spruce (Picea abies (L.) Karst.), Scotch pine (Pinus sylvestris L.) and Blue spruce (Picea pungens Engelm.)

The emission of reduced volatile sulfur compounds from twigs of Norway spruce (Picea abies (L.) Karst.) was measured in the field by cryosampling and gaschromatographic analysis. Trees were growing in the Erzgebirge (E-Germany) at Oberbärenburg and at the Kahleberg and at a third stand in NW-Bavaria (S-Germany). Emission rates were also measured for Scotch pine (Pinus sylvestris L.) and Blue spruce (Picea pungens Engelm.) at the Kahleberg. Twigs still attached to the trees were enclosed in a flow-through gas exchange cuvette. H₂S was detected as the predominant reduced sulfur compound emitted from the twigs. The mean H₂S emission rate from twigs of Norway spruce varied between 0.04 pmol kg^-1 dw s^-1 at Würzburg and 6.21 pmol kg^-1 dw s^-1 at the Kahleberg. Comparing different species at the Kahleberg, the mean H₂S emission rate was almost the same from twigs of Norway spruce (6.2 pmol kg^-1 dw s^-1) and Blue Spruce trees (5.9 pmol kg^-1 dw s^-1) but it was approximately 18 times higher for Scotch pine (110 pmol kg^-1 dw s^-1). The percentage of SO₂-exclusion via H₂S-emission of the tree species investigated at the Kahleberg is calculated on the basis of data on SO₂ fluxes. It is very small for Norway spruce and Blue spruce. However, for Scotch pine, H₂S emission contributes about 10% to the detoxification of SO₂.     

Cryopreservation of in vitro-grown shoot tips of 'Troyer' citrange [Poncirus trifoliata (L.) Raf. × Citrus sinensis (L.) Osbeck.] by encapsulation-dehydration

. In vitro-grown shoot tips excised from preconditioned stock shoots of 'Troyer' citrange were successfully cryopreserved by encapsulation-dehydration. Optimal survival of cryopreserved shoot tips was achieved when encapsulated shoot tips were dehydrated to 17.1% water content. The sucrose concentration in the preconditioning medium significantly influenced the growth and dry matter percentage of the stock shoots as well as subsequent survival of the cryopreserved shoot tips. Maximal growth of stock shoots was obtained in sucrose concentrations in the range of 0.15 M to 0.29 M, while the dry matter percentage increased as sucrose concentration increased up to 0.44 M. The survival of cryopreserved shoot tips increased from 40% to approximately 80% as the sucrose concentration for stock shoots increased from 0.09 M to 0.22 M or 0.29 M. The benzyladenine concentration in the post-culture medium significantly affected the survival and regrowth of the cryopreserved shoot tips. Survival of the shoot tips was lowest when they were post-cultured on benzyladenine-free medium. However, high benzyladenine concentrations (3-4 µM) induced callus formation. Optimal recovery was obtained in post-culture medium containing 2 µM benzyladenine and 0.05 µM !-naphthalene acetic acid. The extraction of shoot tips from alginate beads greatly improved the regrowth of cryopreserved shoot tips.     

Co-expression pattern of dopamine beta-hydroxylase (DβH) and neuropeptide Y (NPY) within sympathetic innervation of ovary and umbilical cord of the European bison (Bison bonasus L.)

Co-expression of dopamine β-hydroxylase (DβH) and neuropeptide Y (NPY) has never been examined in ovary (OV) and umbilical cord (UC) of the European bison (Eb), the endangered wild species. The OV and UC samples were harvested from seasonally eliminated Eb females (45–120 days post coitum). Frozen histological sections were examined by double fluorescent immunohistochemistry (dF-IHC), using the primary mouse anti-DβH monoclonals and rabbit anti-NPY polyclonals and then the immunocomplexes were visualized with FITC and CY3 fluorophores, respectively. Numerous DβH immunoreactive nerve fibers (DβH-IRs) and a little less frequent NPY-IRs were found in the bundle-like structures, innervating mainly perivascular regions of the OV. The NPY-IRs constantly co-expressed DβH, while some DβH-IRs did not express NPY. This specific pattern of innervation was observed both in the stromal and cortical regions of the OV. The simultaneous co-expression of DβH and NPY were also detected in the UC, in which specific single or bundle-like structures ran along the smooth muscles of blood vessels. The spatial-specific co-expression of DβH and NPY in OV and UC, may suggest that these markers are involved in the control of vascularization that regulates nourishing blood circulation required for proper pregnancy maintenance and efficient embryo/fetus development in the Eb.     

The effect of atractyloside and carboxyatractyloside on adenine nucleotide translocation in mitochondria of Vigna sinensis (L.) Savi cv. seridó.

The translocation of adenine nucleotides into mitochondria isolated from hypocotyls of Vigna sinensis (L.) Savi cv. seridó is examined as a function of oxidative phosphorylation. When succinate is used as the oxidizable substrate, atractyloside (10 μm) and carboxyatractyloside (0.4 μm) maximally inhibit the respiration stimulated by 100 μm ADP. For lower concentrations of these substances, the degree of inhibition is greater when the inhibitor is added to a reaction mixture containing mitochondria in a state of active rather than passive respiration. Carboxyatractyloside, a tight binding inhibitor, appears to compete with ADP for the translocator, when examined with concentrations of ADP higher than 50 μm and of Carboxyatractyloside under 0.1 μm. Beyond these limits nonclassical kinetic effects are observed. These data are discussed in the context of models currently described.     

Plastid targeting of E. coli β-glucuronidase and ADP-glucose pyrophosphorylase in maize (Zea mays L.) cells

Summary Dicot and monocot chloroplast targeting peptides (CTPs) were evaluated for their effect on targeting, processing, and expression of two reporter proteins in maize cells. When tested transiently in maize leaf protoplasts, the maize ribulose bisphosphate carboxylase small subunit CTP required the inclusion of the amino terminus of mature small subunit protein to target -glucuronidase (GUS) to the plastid. To remove this amino terminal extension from GUS after import and processing, a repeat of the native processing site was inserted between the native mature protein and the reporter protein. This repeat processing site was used with less efficiency than the native site. Parallel constructs using the Arabidopsis thaliana small subunit and maize granule-bound starch synthase CTPs also localized GUS, but varied in repeat site use and GUS expression levels. Data from the CTP fusions with GUS were generally confirmed with fusions to an allosteric variant of E. coli ADP-glucose pyrophosphorylase. Plastid targeting of this enzyme was required for starch enhancement of transgenic BMS cells.Abbreviations BMS maize Black Mexican Sweet suspension culture cells - CTP chloroplast targeting peptide - glgC16 an allosteric variant of E. coli ADP-glucose pyrophosphorylase - GUS -glucuronidase - LUX luciferase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - SSU small subunit of ribulose bisphosphate carboxylase