SEARCH · PubMed Health

Results for “Populus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

PubMed2005

Significant microsynteny with new evolutionary highlights is detected between Arabidopsis and legume model plants despite the lack of macrosynteny.

The increased amount of data produced by large genome sequencing projects allows scientists to carry out important syntenic studies to a great extent. Detailed genetic maps and entirely or partially sequenced genomes are compared, and macro- and microsyntenic relations can be determined for different species. In our study, the syntenic relationships between key legume plants and two model plants, Arabidopsis thaliana and Populus trichocarpa were investigated. The comparison of the map position of 172 gene-based Medicago sativa markers to the organization of homologous A. thaliana genes could not identify any sign of macrosynteny between the two genomes. A 276 kb long section of chromosome 5 of the model legume Medicago truncatula was used to investigate potential microsynteny with the other legume Lotus japonicus, as well as with Arabidopsis and Populus. Besides the overall correlation found between the legume plants, the comparison revealed several microsyntenic regions in the two more distant plants with significant resemblance. Despite the large phylogenetic distance, clear microsyntenic regions between Medicago and Arabidopsis or Populus were detected unraveling new intragenomic evolutionary relations in Arabidopsis.

Arabidopsis↗

PubMed1989

Differences in ability of NO2 absorption in various broad-leaved tree species.

Absorption of nitrogen dioxide (NO(2)) by various broad-leaved tree species was determined by the (15)N dilution method. The tree seedlings were continuously exposed to 0.3 ppm (microl litre(-1)) NO(2) or the mixture of 0.3 ppm NO(2) and 0.1 ppm O(3) for 30 days. The total amount of NO(2)-nitrogen absorbed by a seedling during the 30-day exposure period primarily depended on the size of the seedling. Among the tested tree species, three cultivars of Populus showed the highest rate of NO(2) absorption per unit leaf area, reaching as much as 0.3 mg N per dm(2) per day. The absorption rates for Populus cultivars were more than four times greater than those for Viburnum or Cinnamomum which had the lowest rate. A highly significant correlation was recognised between the rate of NO(2) absorption and the stomatal conductance among the species. Three cultivars of Populus which had the highest rates of NO(2) absorption were most susceptible to the mixture of NO(2) and O(3). On the contrary, Cinnamomum, Viburnum and Quercus, which showed the lowest rate of NO(2) absorption, were very tolerant to the mixed gas. These results indicate that the species difference in susceptibility to the mixture of NO(2) and O(3) was mainly determined by the difference in rate of absorption of these gases. Exposure to NO(2) alone had no detrimental effect on the tested tree species.

Journal Article↗

PubMed2006

Ecophysiological and seasonal variations in Cd, Pb, Zn, and Ni concentrations in the leaves of urban deciduous trees in Istanbul.

The concentrations of Cd, Pb, Zn and Ni were measured in the leaves of 7 species of deciduous trees, from the urban sites of Istanbul, in both the Spring and Autumn seasons. We detected some differences in the heavy metal concentrations of the control and urban site samples of identical species. Highest concentrations of Cd were detected in Populus, Pb in Aesculus and Robinia, Zn in Populus, and Ni in Robinia and Fraxinus. Lowest chlorophyll content and highest peroxidase (POD) activity was found in the urban site samples of Acer. We have found a positive correlation between the increase in the POD activity and the Pb concentration in Populus. Generally, the tree species investigated in this study, are considered to have different tolerance levels to heavy metal pollution. The data obtained show that the chlorophyll content and the POD activity may be used as heavy metal stress biomarkers in the urban trees.

Air Pollutants↗

PubMed2001

Effect of epiphytes on the extent of necrotic injuries of resistant and susceptible poplar clones infected with Dothichiza populea.

Poplar cuttings of a resistant clone, Populus 'Grandis', and susceptible clones, Populus nigra 'Italica' and Populus 'Robusta', were infected with the pathogenic fungus Dothichiza populea alone, or with the pathogen and one of five strains of epiphytes antagonistic towards it (in vitro), isolated from poplar bark. The extent of injury was examined for 28 days after infection by determining the length of necrotic patches and their area as expressed in per cent of the total area of a cutting or the area of necrotic injuries caused by the pathogen alone. All the poplar cuttings of both the resistant and susceptible clones became diseased when infected with the pathogen alone. Surprisingly enough, however, the least affected clone was the susceptible P. 'Robusta', in which necrotic injuries covered 28% of the total area, as against 40% and 70% in the resistant P. 'Grandis' and the susceptible P. nigra 'Italica', respectively. When the cuttings were infected simultaneously with Dothichiza populea and its antagonistic epiphytes, the diseased area in the resistant clone diminished by as much as two-thirds, and in the susceptible P nigra 'Italica', by one-third in comparison with the area affected by the pathogen alone. In turn, in the susceptible P. 'Robusta' the introduction of three out of five epiphytes stimulated the growth of the pathogenic fungus producing on average a double increase in the necrotic area. The differences in the response of the pathogen to the presence of epiphytes recorded in the susceptible clones indicate a marked influence of the plant on the nature of interactions between its epiphytic microflora and the pathogen.

Antibiosis↗

PubMed2004

Efficiency in removing pollutants by constructed wetland purification systems in Poland.

The aim of this study was to compare the efficiency between Phragmites communis, Salix viminalis, and Populus canadensis in removing the heavy metals Al, Ba, Mn, Ni, Sr, V, Zn, Cd, Cu, and Pb and the eutrophying macroelements phosphate, nitrate, nitrite, ammonia, chloride, sulfate, Ca, Mg, K, and Fe from sewage in subsurface flow constructed wetlands in Poland. The effectiveness of the sewage treatment system was higher in summer compared to winter for the removal of (1) all heavy metals, phosphate (P) and mineral nitrogen (N) for all of species, (2) sulfates (S) for Phragmites and Salix, (3) iron (Fe) for Salix, and (4) chloride (Cl) for Salix and Populus. Analysis of variance indicated that there was no significant difference between the purifications systems in phytoremediation of Mn; so all species were equally effective (99%, prob. level 0.001). The Salix wetland system was most effective in purification of water and removal of macroelements (24-82% in summer, 10-80% in winter with Fe 97%), Cd (58-71%), V (100%), and Zn (84-92%). The Phragmites system was most effective in purification and removal of Al (81-97%), Ba (70-95%), Pb (64-81%), and Sr (24-51%), while in the case of Cu (49-60%) and Ni (55-67%) the Populus wetland system proved most effective. The outflowing water of the wetlands contained elements in amounts exceeding the admissible levels as established for unpolluted water both in winter and summer. Therefore the effectiveness of the observed phytoremediation systems in this study was not sufficient alone to remove these elements and can be considered as a supplemental tool in purification of sewage.

Analysis of Variance↗

PubMedDate not supplied

Water flux in a hybrid poplar stand.

We studied water flux in a four-year-old stand of hybrid Populus during midsummer 1992. Study trees ranged in height from 11.0 to 15.1 m and in diameter from 8.3 to 15.1 cm. The large-leafed Populus hybrid was relatively poorly coupled to the atmosphere. The average value of the stomatal decoupling coefficient, Omega, was 0.66, indicating that, on average, a 10% change in stomatal conductance would result in only a 3 to 4% change in transpiration. During the middle of the summer, the smallest study tree used between 20 and 26 kg of water per day, whereas the largest tree used between 39 and 51 kg day(-1). The maximum observed rate of stand water loss was 4.8 mm day(-1) in this Populus clone. Maximum rates of sap velocity within the xylem were as high as 12.5 m h(-1); measured rates for exposed sunlit branches approached 90% of this maximum. Within-canopy patterns of stomatal conductance generally reflected patterns of incident radiation. Stomatal conductance of foliage grown in shade, even when exposed to non-limiting light and water source conditions, did not increase appreciably. Patterns of stomatal conductance under limiting and non-limiting conditions suggested that both stomatal conductance and leaf specific hydraulic conductivity (LSHC) were linked with the ability to exploit the light resource.

Journal Article↗

PubMed2000

Cell-specific and conditional expression of caffeoyl-coenzyme A-3-O-methyltransferase in poplar.

Caffeoyl coenzyme A-3-O-methyltransferase (CCoAOMT) plays an important role in lignin biosynthesis and is encoded by two genes in poplar (Populus trichocarpa). Here, we describe the expression pattern conferred by the two CCoAOMT promoters when fused to the gus-coding sequence in transgenic poplar (Populus tremula x Populus alba). Both genes were expressed similarly in xylem and differentially in phloem. In xylem, expression was preferentially observed in vessels and contact rays, whereas expression was barely detectable in storage rays and fibers, suggesting different routes to monolignol biosynthesis in the different xylem types. Furthermore, after wounding, fungal infection, and bending, the expression of both genes was induced concomitantly with de novo lignin deposition. Importantly, upon bending and leaning of the stem, the cell-specific expression pattern was lost, and both genes were expressed in all cell types of the xylem. CCoAOMT promoter activity correlated well with the presence of the CCoAOMT protein, as shown by immunolocalization. These expression data may explain, at least in part, the heterogeneity in lignin composition that is observed between cell types and upon different environmental conditions.

Blotting, Western↗

PubMed2003

[Analysis on landscape pattern in the Tuoketuo region of Inner Mongolia].

The Tuoketuo region is located in the middle reach of Yellow River, farming-pastoral zone in Inner Mongolia. In this paper, the vegetation map of study area was compiled by combining TM image and field vegetation survey. Applying several landscape pattern indices such patch size, number, perimeter density, diversity index, evenness index and fragmentation index etc., the landscape pattern of the Tuoketuo region was analyzed on a GIS platform. The result showed that the landscape types in Tuoketuo region mainly consisted of farmland, artificial forest and grassland. The area of farmland was 281.72 km2 and accounted for 33.64% of study region, artificial forest was 22.0%, and grassland was 6.65%. The landscape matrix in northeast part of study area was farmland. On the farmland matrix, Populus + Ulmus patches distributed with centering of residential spot, there were 89 patches. The patch density was 2.568 patch.km-2, and the mean patch area of Populus + Ulmus was only 0.39 km2, therefore, the characteristics of matrix and patch was very typical. Perimeter density of Populus + Ulmus and hill-gully were higher than other landscape types, indicating that the fragmentation degree of the former was higher, and hill-gulf was cut seriously in study area. All of these results emphasize that human activity had a strong impact on the landscape pattern in the Tuoketuo region.

Agriculture↗

PubMed2006

Mapping the proteome of poplar and application to the discovery of drought-stress responsive proteins.

Poplar is the first forest tree genome to be decoded. As an initial step to the comprehensive analysis of poplar proteome, we described reference 2-D-maps for eight tissues/organs of the plant, and the functional characterization of some proteins. A total of 398 proteins were excised from the gels. About 91.2% were identified by nanospray LC-MS/MS, based on comparison with 260,000 Populus sp. ESTs. In comparison, reliable PMFs were obtained for only 51% of the spots by MALDI-TOF-MS, from which 43% (83 spots) positively matched gene models of the Populus trichocarpa genome sequence. Among these 83 spots, 58% matched with the same proteins as identified by LC-MS/MS, 21.7% with unknown function proteins and 19.3% with completely different functions. In the second phase, we studied the effect of drought stress on poplar root and leaf proteomes. The function of up- and down-regulated proteins is discussed with respect to the physiological response of the plants and compared with transcriptomic data. Some important clues regarding the way poplar copes with water deficit were revealed.

Databases, Protein↗

PubMed2003

Inhibitory activity of plant extracts on nitric oxide synthesis in LPS-activated macrophages.

Nitric oxide (NO) produced in large amounts by inducible nitric oxide synthase (iNOS) is known to be responsible for the vasodilation and hypotension observed in septic shock and inflammation. Inhibitors of iNOS, thus, may be useful candidates for the treatment of inflammatory diseases accompanied by overproduction of NO. We prepared alcoholic extracts of woody plants and screened the inhibitory activity of NO production in lipopolysaccharide (LPS)-activated macrophages after the treatment of these extracts. Among 83 kinds of plant extracts, 23 kinds of extracts showed potent inhibitory activity of NO production above 60% at the concentration of 80 micro g/ml. Some of potent extracts showed dose dependent inhibition of NO production of LPS-activated macrophages at the concentration of 80, 40, 20 micro g/ml. Especially, Artemisia iwayomogi, Machilus thunbergii, Populus davidiana and Populus maximowiczii showed the most potent inhibition (above 70%) at the concentration of 40 micro g/ml. Inhibitory activity of NO production was concentrated to nonpolar solvent fractions (ethyl ether and/or ethyl acetate soluble fractions) of Artemisia iwayomogi, Machilus thunbergii and Morus bombycis. These plants are promising candidates for the study of the activity-guided purification of active compounds and would be useful for the treatment of inflammatory diseases and endotoxemia accompanying overproduction of NO.

Animals↗

PubMed2005

Molecular characterization of PeNhaD1: the first member of the NhaD Na+/H+ antiporter family of plant origin.

PeNhaD1 encodes a putative Na+/H+ antiporter from the salt-resistant tree Populus euphratica. It is the first characterization of a member of the NhaD type ion transporter family of plant origin. Homology searches revealed its close relation to functionally characterized microbial Na+/H+ antiporters VpNhaD and VcNhaD. Na+/H+ antiporters have proven to play a key role in salt resistance, both in plants and bacteria. Under salt stress transcript levels of PeNhaD1 were maintained only in the salt-resistant P. euphratica, but collapsed in Populus x canescens, a salt-sensitive species. To address the function of PeNhaD1, complementation studies with the salt-sensitive Escherichia coli EP432 mutant strain, lacking activity of the two Na+/H+ antiporters EcNhaA and EcNhaB were carried out. PeNhaD1 was able to restore growth of EP432 under stress imposed by up to 400 mM NaCl demonstrating its protective function. Growth rates of EP432 were always highest at pH 5.5 while growth was suppressed under salt stress at pH 7.0 and pH 8.0 suggesting that the antiporter activity is strongly pH dependent. Element analyses of EP432 cells complemented with PeNhaD1 growing under salt stress showed that salt resistance was correlated with a significant reduction in sodium accumulation. These results suggest that PeNhaD1 might play a role in the salt resistance of P. euphratica.

Adaptation, Physiological↗

PubMed2006

Identification of a new family of plant proteins loosely related to glutaredoxins with four CxxC motives.

The annotation of the recently released Populus trichocarpa genome, has allowed us to characterize extensively the multigenic families of the redoxin proteins. Proteins with two cysteines separated by two amino acids (CxxC motif) are often involved in redox reactions by promoting the formation, reduction or isomerization of disulfide bonds or by binding prosthetic groups or metals. We report here the presence of a new protein family in higher plants, constituted of 19 members in Populus trichocarpa, 15 in Arabidopsis thaliana and 17 in Oryza sativa. These proteins are almost specific to higher plants, with only two homologous genes found in mammals and arthropoda but none in other kingdoms. While these proteins were predicted as glutaredoxin-like proteins (GRL) in the automatic annotation procedure, they do not share the major conserved features of glutaredoxins but instead they display four conserved CxxC motives. A classification of these proteins, based on sequence similarity, gene structure and predicted cellular localization is proposed. The expression of these genes was also investigated by analyzing EST databases and Arabidopsis microarray results.

Amino Acid Motifs↗

PubMed2005

Ability of transgenic poplars with elevated glutathione content to tolerate zinc(2+) stress.

Phytoremediation potentials of four poplar lines, Populus nigra (N-SL clone), Populus canescens, and two transgenic P. canescens clones were investigated using in vitro leaf discs cultures. The transgenic poplars overexpressed a bacterial gene encoding gamma-glutamylcysteine synthetase in the cytosol (11ggs) or in the chlopoplasts (6LgI), and therefore, they contained an elevated level of glutathione. Leaf discs of poplar clones were exposed to different concentrations of ZnSO(4) for 21 days. Zinc(2+) was phytotoxic only at high concentrations (10(-2) to 10(-1) M) at all P. canescens lines, but P. nigra was more sensitive. Transgenic poplars showed elevated heavy metal uptake as compared to the nontransformed clones. Treatments with zinc(2+) strongly induced the activity of glutathione S-transferase enzyme in untransformed poplar lines but to a lesser extent in the transgenic clones. These results suggest that transgenic poplars are more suitable for phytoremediation of soils contaminated with zinc(2+) than wild-type plants.

Adaptation, Physiological↗

PubMed2006

Identification of differentially expressed genes induced by ozone stress in sensitive and tolerant poplar hybrids.

The differential expression of genes induced by an acute ozone treatment was analysed in two poplar clones, i.e. Populus deltoides x maximowiczii, Eridano clone, and Populus x euoramericana, I-214 clone, respectively, sensitive and tolerant to this pollutant, performing suppression subtractive hybridization (SSH). From the obtained cDNA libraries several clones were obtained, which corresponded to differentially regulated genes. Preliminary expression analyses of four genes, Fs23A-LRP, Ft33B-CaBP, Ft312B-WRKY, and Ft32C-WAK identified by the primary screening, were conducted by semi-quantitative RT-PCR to evaluate the ozone responsiveness of the libraries. The most interesting finding is the co-activation of a wall associated kinase and a WRKY transcription factor in response to O(3) stress.

Air Pollutants↗

PubMed2003

Significant increases in pulping efficiency in C4H-F5H-transformed poplars: improved chemical savings and reduced environmental toxins.

The gene encoding ferulate 5-hydroxylase (F5H) was overexpressed in poplar (Populus tremula x Populus alba) using the cinnamate-4-hydroxylase (C4H) promoter to drive expression specifically in cells involved in the lignin biosynthetic pathway and was shown to significantly alter the mole percentage of syringyl subunits in the lignin, as determined by thioacidolysis. Analysis of poplar transformed with a C4H-F5H construct demonstrated significant increases in chemical (kraft) pulping efficiency from greenhouse-grown trees. Compared to wild-type wood, decreases of 23 kappa units and increases of >20 ISO brightness units were observed in trees exhibiting high syringyl monomer concentrations. These changes were associated with no significant modification in total lignin content and no observed phenotypic differences. C4H-F5H-transformed trees could increase pulp throughputs at mills by >60% while concurrently decreasing chemicals employed during processing (chemical pulping and bleaching) and, consequently, the amount of deleterious byproducts released into the environment.

Arabidopsis Proteins↗

PubMed2002

The vascular expression pattern directed by the Eucalyptus gunnii cinnamyl alcohol dehydrogenase EgCAD2 promoter is conserved among woody and herbaceous plant species.

Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) catalyses the last step in the synthesis of the monomeric precursors of lignin. Here, we demonstrate that the vascular expression pattern conferred by the Eucalyptus gunnii EgCAD2 promoter in transgenic poplar (Populus tremula x Populus alba) is conserved in another perennial woody angiosperm of economic interest (Vitis vinifera L.), as well as in a model herbaceous plant (Nicotiana tabacum L.). Furthermore, promoter deletion analysis performed in both tobacco and poplar allowed us to identify the proximal region [-340/-124] as essential for vascular cambium/xylem-specific expression whereas the [-124/+117] region was shown to contain cis element-driving activity in phloem fibres. Interestingly, the [-340/-124] fragment contains an AC-rich cis-acting element present in numerous genes of the phenylpropanoid pathway expressed in xylem tissues, and known as a consensus Myb transcription factor binding site, suggesting that common Myb sites may provide a mechanism by which different steps of phenylpropanoid metabolism are coordinately regulated and expressed in vascular tissues. We have also shown in both tobacco and poplar that the EgCAD2 promoter is inducible by wounding and the cis-elements responsible for wounding responsiveness are located in the distal promoter region. Taken together, our data suggest that the mechanisms controlling developmental and wounding inducible expression of the EgCAD2 promoter are conserved among perennial woody and annual herbaceous plant species enabling us now to investigate in depth the transcriptional regulation of the EgCAD2 promoter in tobacco.

Alcohol Oxidoreductases↗

PubMed2005

Host-associated populations in the lettuce root aphid, Pemphigus bursarius (L.).

Pemphigus bursarius is a host-alternating aphid in which annual rounds of sexual reproduction on its primary host, Populus nigra, are interspersed with parthenogenesis on a range of secondary hosts. Evidence was sought for the existence of genetically distinct populations, associated with different secondary hosts, in P. bursarius. Microsatellite markers revealed that genetically distinct populations were present on three different secondary host species. Microsatellites were also used, in conjunction with mitochondrial DNA sequence variation, to investigate the relationships between aphids on Populus, following sexual reproduction, and those on the secondary hosts. Evidence was found for a distinct, cyclically parthenogenetic population that exploited Lactuca sativa as its secondary host. In contrast, populations associated with Matricaria inodora appeared to be largely composed of obligate parthenogens or may even have been another species of Pemphigus. Populations on Lapsana communis appeared to be a mixture of cyclical and obligate parthenogens and were more genetically heterogeneous than those on other secondary hosts, possibly due to founder effects. Experiments to measure the performance of P. bursarius clones on different secondary hosts were inconclusive, failing to demonstrate either the presence or absence of adaptations to secondary hosts.

Animals↗

PubMedDate not supplied

Poplar genomics is getting popular: the impact of the poplar genome project on tree research.

Trees, due to their long life-span, have characteristics that distinguish them from annual, herbaceous plants. It is likely that many of these properties are based on a tree-specific genetic foundation. The U.S. Department of Energy initiated a genome-sequencing project for Populus, a model perennial plant. Through international collaboration and input to the sequencing effort, the annotated whole genome sequence of Populus trichocarpa will be released to the public in early 2004. This genomic resource will, for the first time, allow comparison between a perennial and an annual plant on a whole genome basis and therefore provide clues for molecular research on tree-specific questions like dormancy, development of a secondary cambium, juvenile-mature phase change, or long-term host-pest interactions. The approximately 520 Mbp of annotated genomic sequence will complement and expand the knowledge provided so far by the 125,000 ESTs from poplar that are available in public databases. This article introduces the international poplar research programmes and points out the significance of the poplar genome project for plant research.

Databases, Genetic↗