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At least 343 records · Page 19Linked to original sources
PubMed2004

Time of flight secondary ion mass spectrometry studies of the distribution of metals between the soil, rhizosphere and roots of Populus tremuloides Minchx growing in forest soil.

Time of flight secondary ion mass spectroscopy has been used to study the metal distribution at the soil/root interface of tree roots extracted from smelter-impacted soils. The results, augmented by scanning electron microscopy, show that the technique is capable of resolving metal distributions at the cellular level. In addition, the distribution of metals between the root plaque and the root interior may be useful in interpreting local metal transport mechanisms.

Metals↗
PubMed2005

Deposition velocities to Sorbus aria, Acer campestre, Populus deltoides X trichocarpa 'Beaupré', Pinus nigra and X Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment.

Trees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle size on the deposition velocity of particles (Vg) to five urban tree species (coniferous and broadleaved) measured at two field sites, one urban and polluted and a second more rural. The larger uptake to conifers is confirmed, and for broadleaves and conifers Vg values are shown to be greater for ultra-fine particles (Dp < 1.0 microm) than for fine and coarse particles. This is important since finer particles are more likely to be deposited deep in the alveoli of the human lung causing adverse health effects. The finer particle fraction is also shown to be transported further from the emission source; in this study a busy urban road. In further sets of data the aqueous soluble and insoluble fractions of the ultra-fines were separated, indicating that aqueous insoluble particles made up only a small proportion of the ultra-fines. Much of the ultra-fine fraction is present as aerosol. Chemical analysis of the aqueous soluble fractions of coarse, fine and ultra-fine particles showed the importance of nitrates, chloride and phosphates in all three size categories at the polluted and more rural location.

Acer↗
PubMed2006

Changes in carbohydrate metabolism in fine roots of the native European black poplar (Populus nigra L.) in a heavy-metal-polluted environment.

Effects of copper-smelter-related deposition of heavy metals in the soil on carbohydrate metabolism of fine roots of the native European black poplar were investigated in spring and autumn. Total soluble non-structural carbohydrates in fine roots from trees growing in the polluted habitat were lower than in a control site, but this was directly associated only with a lower raffinose concentration. Neither glucose nor fructose concentrations differed significantly between polluted and unpolluted sites. In contrast, the galactose concentration was higher in the presence of heavy metals, especially in autumn. Also the stachyose concentration was higher in the polluted site, but only in autumn, suggesting it could be an alternative way of detoxification of galactose. No difference between control and polluted stands was observed in sucrose concentration. However, estimates of sucrolytic activity revealed markedly higher activities of sucrose synthase (SuSy), soluble acid (AI) and neutral (NI) invertases in the polluted stand than in the control. In contrast, the estimated glycolytic enzyme activities were not affected by the presence of heavy metals in soil.

Glucosyltransferases↗
PubMed2003

Quantitative trait loci for growth trajectories in Populus.

Growth trajectories are a biological process important to plant and animal breeding, and to evolutionary genetic studies. In this article, we report the detection of quantitative trait loci (QTLs) responsible for growth trajectories in poplars that are used as a model system for the study of forest biology. These QTLs were localized on a genetic linkage map of polymorphic markers using a statistical mapping method incorporating growth-curve models. The effects of the QTLs on growth are described as a function of age, so that age-specific changes in QTL effects can be readily projected throughout the entire growth process. The QTLs identified display increased effects on growth when trees age, yet the timing of QTL activation is earlier for stem height than diameter, which is consistent with the ecological viewpoint of canopy competition. The implications of the results for breeding and silviculture are discussed.

Genetic Linkage↗
PubMed2003

Exposure of the roots of Populus nigra L. cv. Loenen to PAHs and its effect on growth and water balance.

Poplar cuttings were cultivated for 4 weeks in a substrate, which consisted of a combination of sand and nutrient solution. The plants were treated for 24 days with BaP, Chr, Ant, Phen, P and Flt, single or in combination. The concentration of the PAHs ranged from 0.1-200 mg/kg substrate. The results of the pollution experiments can be summarized as follows: 1. The most significant deviations between the test groups and the control can be observed for transpiration, nutrient solution uptake, and root mass. 2. Although transpiration and nutrient solution uptake are significantly lower for all the treated groups than for the control group, the water content of the leaves was not affected by PAHs. 3. The biomass of the shoots and the growth in shoot length do not react as strongly to exposure to PAHs as transpiration, nutrient solution uptake and the volume of the roots. 4. The differences in leaf weight and leaf surface area are significantly less pronounced compared to the control groups. Growth inhibition is most evident with Flt. Growth and absorption of the nutrient solution dropped with just Flt 0.1 mg/kg substrate. When the substrate concentration was increased, growth and nutrient solution uptake dropped considerably and at a concentration of Flt 200, 5 of the 11 test plants died before the end of the period of exposure. Nutrient solution uptake and shoot development of the test plants decreased in the following order: BaP H approximately = Chr > Ant > Phen > Pyr > Flt.

Absorption↗
PubMed2005

Clonal and spatial genetic structures of aspen (Populus tremuloides Michx.).

To portray aspen clonal and spatial genetic structures, we mapped and genotyped trees in two 1-ha plots, each containing three aspen cohorts originating from fire or subsequent secondary disturbances. We used four microsatellite loci to identify aspen clones and increment core analysis to determine tree age. Clonal dimensions were measured by the maximum distance between two ramets and the number of ramets per genet. Standard normal deviate (SND) was used to assess the spatial distribution of aspen genets and cohorts, and multivariate spatial genetic autocorrelations to assess the spatial distribution of aspen genetic variation. Most aspen genets consisted of only one ramet (> 75%). Median clonal dimensions were 19 and 29 m (maxima: 104 and 72 m in the two plots). No segregation was observed between clones. Aspen cohorts were spatially segregated but trees were spatially aggregated within old and medium-aged cohorts. In contrast, trees were more randomly distributed within the youngest cohorts. This coincided with a spatial genetic autocorrelation at small scales (up to 30 m) in the older cohorts and a more random genetic distribution in the youngest ones. Our results suggest that aspen spatial genetic structuring reflects the spatial patterns produced by the regeneration of discrete cohorts at different stages of succession. Vegetative reproduction leads to aspen genetic spatial structuring at small scales (few metres) until midsuccession. However, as the stand gets older, the spatial distribution of aspen trees and genetic structure evolve from a structured pattern to a more random one under a gap disturbances regime.

Clone Cells↗
PubMed2004

Forest tent caterpillars (Malacosoma disstria) induce local and systemic diurnal emissions of terpenoid volatiles in hybrid poplar (Populus trichocarpa x deltoides): cDNA cloning, functional characterization, and patterns of gene expression of (-)-germacrene D synthase, PtdTPS1.

Feeding forest tent caterpillars (FTCs) induced local and systemic diurnal emissions of (-)-germacrene D, along with (E)-beta-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), benzene cyanide, and (E,E)-alpha-farnesene, from leaves of hybrid poplar. FTC feeding induced substantially higher levels of volatiles in local and systemic leaves than did mechanical wounding. A full-length poplar sesquiterpene synthase cDNA (PtdTPS1) was isolated and functionally identified as (-)-germacrene D synthase. Expression of PtdTPS1, expression of genes of early, intermediate and late steps in terpenoid biosynthesis, and expression of a lipoxygenase gene (PtdLOX1) were analyzed in local FTC-infested and systemic leaves. Transcript levels of PtdTPS1 and PtdLOX1 were strongly increased in response to herbivory. PtdTPS1 was also induced by mechanical wounding or by methyl jasmonate (MeJA) treatment. FTC feeding did not affect transcript levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), and isoprene synthase (IPS). Two other TPS genes, PtdTPS2 and PtTPS3, and farnesyl diphosphate synthase were only very transiently induced. These results illustrate differential expression of terpenoid pathway genes in response to insect feeding and a key function of (-)-germacrene D synthase PtdTPS1 for herbivore-induced local and systemic volatile emissions in hybrid poplar. FTC-induced transcripts of PtdTPS1 followed diurnal rhythm. Spatial patterns of FTC-induced PtdTPS1 transcript accumulation revealed acropetal but not basipetal direction of the systemic response. Implications for tritrophic poplar-FTC-predator/parasitoid interactions are discussed.

Acetates↗
PubMedDate not supplied

AFLP analysis and improved phytoextraction capacity of transgenic gshI-poplar clones (Populus x canescens L.) for copper in vitro.

Clone stability and in vitro phytoextraction capacity of vegetative clones of P. x canescens (2n = 4x = 38) including two transgenic clones (ggs11 and lgl6) were studied as in vitro leaf disc cultures. Presence of the gshI-transgene in the transformed clones was detected in PCR reactions using gshI-specific primers. Clone stability was determined by fAFLP (fluorescent amplified DNA fragment length polymorphism) analysis. In total, 682 AFLP fragments were identified generated by twelve selective primer pairs after EcoRI-MseI digestion. Four fragments generated by EcoAGT-MseCCC were different (99.4% genetic similarity) which proves an unexpectedly low bud mutation frequency in P. x canescens. For the study of phytoextraction capacity leaf discs (8 mm) were exposed to a concentration series of ZnSO4 (10(-1) to 10(-5) M) incubated for 21 days on aseptic tissue culture media WPM containing 1 microM Cu. Zn2+ caused phytotoxicity only at high concentrations (10(-1) to 10(-2) M). The transgenic poplar cyt-ECS (ggs11) clone, as stimulated by the presence of Zn, showed elevated heavy metal (Cu) uptake as compared to the non-transformed clone. These results suggest that gshI-transgenic poplars may be suitable for phytoremediation of soils contaminated with zinc and copper.

Base Sequence↗
PubMed2004

[Differential expression on cell wall formative genes in cell suspension cultures of Populus tomentosa Carr].

With fine and granular suspension cultures established from P. tomentosa, differential expression of 12 genes related to cell wall formation including cell expansion, cellulose synthesis, lignin synthesis, etc, were investigated by reverse transcript PCR (RT-PCR) technique. Fine suspension cells showed high expression on 3 alpha-Exp genes with the highest alpha-Exp2 followed by alpha-Exp3 and alpha-Exp1 suggesting their strong cell expansion, while granular suspension cells only exist high expression on alpha-Exp3 indicating their later period of cell expansion or initial stage of secondary cell wall formation. Among the 6 genes relating to cellulose synthesis, both fine and granular cultures have high expression on CesA4 and CaSy1 and some expression on CesA1, CesA3-1 and CesA3-2, indicating their primary cell wall formation initiated, however a little higher expression on CesA3-1 and CesA3-2 in granular cells may reflect its more cellulose synthesis and more primary cell wall formation. The occurrence of Lac1 and Unk1 could not been detected in the 2 cell suspension cultures, showing no significant lignin biosynthesis and matural secondary cell wall formation.

Cell Wall↗
PubMedDate not supplied

Cadmium phytoextraction potential of poplar clones (Populus spp.).

Biomass production, leaf number and area, photosynthetic and dark respiration rates, leaf concentration of photosynthetic pigments, nitrate reductase activity, as well as cadmium concentrations in leaves, stem, and roots were measured in poplar clones PE 4/68, B-229, 665, and 45/51. Plants were grown hydroponically under controlled conditions and treated with two different cadmium (Cd) concentrations (10(-5) and 10(-7) M) in the same background solution (Hoagland's solution). The presence of Cd did not cause serious disturbance of growth and physiological parameters in the studied poplar clones. Cd concentrations in plant tissues reflected external concentrations. In treated plants, root contents increased from 38.57 to 511.51 ppm, leaf contents from 0.91 to 7.50, while stem contents ranged from 1.37 to 9.50 ppm.

Biodegradation, Environmental↗
PubMed1993

A family of wound-induced genes in Populus shares common features with genes encoding vegetative storage proteins.

Two wound-inducible cDNAs from poplar leaves show sequence identity to vegetative storage proteins (VSP) that accumulate seasonally in poplar bark tissues. We have compared the genomic organization, cDNA sequences and expression of the genes encoding the wound-inducible cDNAs (win4) with that of a bark VSP (called bark storage protein, or BSP). There appear to be several win4 genes in the poplar genome which segregate as a single locus and are therefore likely to be clustered. The same is true of the BSP genes. The win4 locus is linked (map distance of 5 cM) to the BSP locus, consistent with a common evolutionary origin of the genes. A near full-length win4 cDNA shows 75% sequence identity to BSP cDNAs. Both win4 and BSP are systemically wound-inducible; win4 transcripts accumulate in leaves and stems, whereas BSP transcripts accumulate almost exclusively in stems. A phloem transport-dependent signaling mechanism appears to be involved in systemic win4 expression after wounding. In contrast to BSP gene expression, win4 genes are not expressed in response to short day conditions. The data indicate win4 and BSP genes are differentially regulated, and their products may play important roles in the storage and reallocation of nitrogen in perennial plants.

Amino Acid Sequence↗