Search results for "Plant Stems"
showing 10 items of 31 documents
Microbial community structure in soils with decomposing residues from plants with genetic modifications to lignin biosynthesis
2006
Lignin is a major determinant of the decomposition of plant materials in soils. Advances in transgenic technology have led to the possibility of modifying lignin to improve the pulping properties of plant materials for papermaking. Previous studies have shown that lignin modifications also affect the rate of plant material decay in soil. The aim of this work was to investigate short-term changes in soil microbial community structures when tobacco residues with reduced activity of enzymes in the monolignol pathway decompose. The residues from lignin-modified plants all decomposed faster than unmodified plant materials. The relative proportions of some of the structural groups of microbial ph…
A New Aromatic Compound from the Stem Bark of Terminalia catappa
2015
A new aromatic compound 3,4,5-trimethoxyphenyl-1- O-(4-sulfo)-β-D-glucopyranoside (1), in addition to two triterpenoid saponins (chebuloside II, arjunoglucoside II), two triterpenes (arjunolic acid and 3-betulinic acid) and sitosterol-3- O-β-D-glucopyranoside have been isolated from the barks of Terminalia catappa. Their structures have been established on the basis of spectroscopic techniques (1D/2D NMR) and MS. Their cytotoxicity and anti-inflammatory activity, together with the antioxidant capacity of compound 1 were also evaluated.
A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.
2014
Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, ex…
Uniform climate sensitivity in tree-ring stable isotopes across species and sites in a mid-latitude temperate forest.
2014
Tree-ring stable isotopes, providing insight into drought-induced eco-physiological mechanisms, are frequently used to reconstruct past changes in growing season temperature and precipitation. Their climatic response is, however, still not fully understood, particularly for data originating from non-extreme, mid-latitude environments with differing ecological conditions. Here, we assess the response of δ(13)C, δ(18)O and tree-ring width (TRW) from a temperate mountain forest in the Austrian pre-Alps to climate and specific drought events. Variations in stem growth and isotopic composition of Norway spruce, common beech and European larch from dry, medium and moist sites are compared with re…
Effects of indole-3-acetic acid on Sinorhizobium meliloti survival and on symbiotic nitrogen fixation and stem dry weight production
2009
We evaluated the effects of the main auxin phytohormone, indole-3-acetic acid (IAA), on the central metabolism of Sinorhizobium meliloti strain 1021. We either treated the Sinorhizobium meliloti 1021 strain with 0.5 mM IAA (1021+) or use a derivative, RD64, of the same strain harbouring a pathway for IAA biosynthesis converting tryptophan into IAA via indoleacetamide. We assayed the activity of key enzymes in the major energy-yielding pathways (Entner-Doudoroff, Embden-Meyerhof-Parnas, pentose phosphate, glyoxylate bypass and tricarboxylic acid cycle). We found that activity of two main regulative tricarboxylic acid (TCA) cycle enzymes was increased. Citrate synthase (CS) activity, as compa…
Essential Oil Composition of Stems and Fruits of Caralluma europaea N.E.Br. (Apocynaceae)
2010
The essential oil of the stems and fruits of Caralluma europaea (Guss.) N.E.Br. (Apocynaceae) from Lampedusa Island has been obtained by hydrodistillation and its composition analyzed. The analyses allowed the identification and quantification of 74 volatile compounds, of which 16 were aromatic and 58 non-aromatic. Stems and fruits contained 1.4% and 2.7% of aromatic compounds respectively, while non-aromatic were 88.3% and 88.8%. Non-aromatic hydrocarbons were the most abundant compounds in both organs, followed by fatty acids. Data showed differences in the profiles between stems and fruits which shared only eighteen compounds; stems accounted for 38 compounds while fruits for 53. Fruits …
Steroidal saponins from two species of Dracaena.
2010
Four new steroidal saponins (1-4) were isolated from the stem and bark of two species of Dracaena: deistelianosides A and B (1 and 2) from D. deisteliana and arboreasaponins A and B (3 and 4) from D. arborea. Six known saponins and one known sapogenin were also isolated. The structures of 1-4 were established as diosgenin 3-O-[3-O-sulfate-alpha-l-rhamnopyranosyl-(1-->4)]-beta-d-glucopyranoside (1), 1-O-beta-d-xylopyranosyl-(1-->2)-[alpha-l-rhamnopyranosyl-(1-->3)]-beta-d-fucopyranosyl(23S,24S)-spirosta-5,25(27)-diene-1beta,3beta,23alpha,24alpha-tetrol 24-O-alpha-l-arabinopyranoside (2), pennogenin-3-O-alpha-l-rhamnopyranosyl-(1-->2)-[alpha-l-rhamnopyranosyl-(1-->3)]-[6-O-acetyl]-beta-d-gluc…
Antileukemic ancistrobenomine B and related 5,1′-coupled naphthylisoquinoline alkaloids from the Chinese liana Ancistrocladus tectorius
2017
A striking feature of the metabolite pattern of the Southeast Asian liana Ancistrocladus tectorius (Ancistrocladaceae) is the predominance of 5,1′-coupled naphthylisoquinoline alkaloids. About 20 alkaloids of this coupling type have so far been discovered in this plant species. Here, we report on the isolation of four new 5,1′-linked naphthylisoquinolines from the twigs and stems of A. tectorius. Two of them, the ancistrobenomines B (5) and C (6), belong to the very rare group of alkaloids with a fully dehydrogenated isoquinoline portion. Likewise unusual for naphthylisoquinoline alkaloids is the presence of a hydroxymethylene group at C-3. Within the large class of meanwhile ca. 180 such n…
Dual mode of action of grape cane extracts against Botrytis cinerea
2019
International audience; Crude extracts of Vitis vinifera canes represent a natural source of stilbene compounds with well characterized antifungals properties. In our trials, exogenous application of a stilbene extract (SE) obtained from grape canes on grapevine leaves reduces the necrotic lesions caused by Botrytis cinerea. The SE showed to possess a direct antifungal activity by inhibiting the mycelium growth. The activation of some grapevine defense mechanism was also investigated. H2O2 production and activation of mitogen-activated protein kinase (MAPK) phosphorylation cascades as well as accumulation of stilbenoid phytoalexins were explored on grapevine cell suspension. Moreover, the t…
Chemical composition, antimicrobial and antioxidant activity of the essential oils from Pimpinellatragium Vill. subsp. glauca (C. Presl.) C. BrulloBr…
2013
The essential oils from flowers, leaves and stems hydrodistilled from Pimpinella tragium Vill, subsp. glauca were characterised by GC and gas chromatography-mass spectrometry analysis. The C-12 nor-sesquiterpenes are the principal class of metabolites (56.6-70.6%) among which geijerene (28.9÷49.3%) and pregeijerene (10÷19.1%) predominate. Antimicrobial and antioxidant activities were evaluated. The minimum inhibitory concentration values indicate that oil obtained from the stems is the most active for antimicrobial activities and the sample with the biggest antioxidant capacity is the flower oil.