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PubMed2001

Genetic improvement of poplar feedstock quality for ethanol production.

Opportunities for matching chemical and physical properties of woody feedstocks to ethanol production process requirements via genetic improvement have long been recognized. Exploitation is now feasible owing to advances in trait measurement, breeding, and gene transfer technologies. Poplar genetic parameters are favorable largely for reducing lignin and increasing cellulose contents and specific gravity. Transgenic poplars with decreased lignin and increased cellulose contents, but otherwise normal growth and development, have been produced via genetic transformation. The long-standing debate on feasibility has thus become one of when, not if, designer varieties will become available.

Biomass↗

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↗

PubMedDate not supplied

RT-PCR analysis and stress response capacity of transgenic gshI-poplar clones (Populus x canescens) in response to paraquat exposure.

Stress response capacity (Fv/Fm at 690 nm and F690/F735 at Fmax) of untransformed hybrid poplar, Populus x canescens (P tremula x P alba), and two transgenic lines overexpressing gamma-ECS (gamma-glutamylcysteine synthetase) either in the cytosol (cyt-ECS) or in the chloroplast (chl-ECS) was studied in response to the herbicide paraquat (4.0 x 10(-9) to 4.0 x 10(-6) M) for 21 days. Significant differences at sublethal (4.0 x 10(-7) M) and bleaching (4.0 x 10(-6) M) concentrations of paraquat were observed with about a two-fold and eight-fold decrease in the photosynthetic activity (Fv/Fm at 690 nm and F690/F735 at Fmax), respectively. None of the gshI transgenic lines (cyt-ECS, chl-ECS) with elevated GSH content exhibited significant tolerance to paraquat. Semiquantitative RT-PCR of the cyt-ECS clone was used for gene expression analysis of the nuclear encoded rbcS gene and the stress responsive gst gene. Expression of the constitutively expressed 26SrRNA ribosomal gene was probed as a control for all RT-PCR reactions. The relative intensities of gene expressions normalized to the level of 26SrRNA intensity showed a 50% decrease in the nuclear encoded rbcS expression and a 120% increase in the stress responsive gst gene expression of the paraquat treated (4.0 x 10(-7) M) samples of the transgenic poplar line (cyt-ECS).

Animals↗

PubMedDate not supplied

Hybrid poplar and forest soil response to municipal and industrial by-products: a greenhouse study.

Little research has been conducted in the Lake States (Minnesota, Wisconsin, and Michigan) to evaluate the effects of municipal and industrial by-product applications on the early growth of short rotation woody crops such as hybrid poplar. Anticipated shortages of harvestable-age aspen in the next decade can be alleviated and rural development can be enhanced through the application of by-products to forest soils. This study was conducted to evaluate the effects of inorganic fertilizer, boiler ash, biosolids, and the co-application of ash and biosolids application on tree growth and soil properties by measuring hybrid poplar clone NM-6 (Populus nigra L. x P. maximowiczii A. Henry) yield, nutrient uptake, and select post-harvest soil properties after 15 wk of greenhouse growth. Treatments included a control of no amendment; agricultural lime; inorganic N, P, and K; three types of boiler ash; biosolids application rates equivalent to 70, 140, 210, and 280 kg available N ha(-1); and boiler ash co-applied with biosolids. All of the by-products treatments showed biomass production that was equal to or greater than inorganic fertilizer and lime treatments. A trend of increased biomass with increasing rates of biosolids was observed. Soil P concentration increased with increasing rates of biosolids application. None of the by-products treatments resulted in plant tissue metal concentrations greater than metal concentrations of plant tissue amended with inorganic amendments. Biosolids, boiler ash, and the co-application of biosolids and boiler ash together on forest soils were as beneficial to plant growth as inorganic fertilizers.

Biomass↗

PubMed2005

Behavior of Escherichia coli cells and Bacillus cereus spores on poplar wood crates by impedance measurements.

Dry poplar wood crates and glass surfaces (bottoms of Pyrex flasks) were contaminated with aqueous suspensions of Escherichia coli Collection de l'Institut Pasteur (CIP) 54.8 cells or Bacillus cereus CIP 78.3 spores. After different periods of storage at 25 degrees C, the number of cells still present on both surfaces was determined by impedance microbiology. The physical and chemical properties of the wood greatly and rapidly decreased the number of cells. After 4 h of contact time, B. cereus residual metabolic activity corresponded to less than 10% of the initial inoculum level. With a low inoculum level of 2.4 x 10(2) E. coli cells, sterility of the wood was obtained after a contact time of 24 h. With a higher inoculum level of 10(6) E. coli cells, only a few viable bacteria, corresponding to the metabolic activity of four cells, could be recovered after a prolonged contact time of 145 h. Conversely, under the same conditions of storage, when bacteria were deposited on inert and nonporous materials such as glass surfaces, growth occurred. After 24 h of contact time at 25 degrees C, bacterial populations were about 10(9) cells for E. coli and 10(7) cells for B. cereus. Under our experimental conditions after a prolonged contact time, wood exhibited growth-inhibiting properties and cells were no longer metabolically active. These results indicate that the potential for cross-contamination of foods stored directly in contact with previously contaminated poplar wood crates is low under our experimental conditions.

Bacillus cereus↗

PubMed1999

[Introduction of rabbit defensin NP-1 gene into poplar (P. tomentosa) by Agrobacterium-mediated transformation].

Rabbit defensin NP-1 possesses a broad resistant spectrum to pathogens. In this work, we have transferred the NP-1 gene into poplar plants by Agrobacterium-mediated transformation. PCR amplification and Southern analysis showed that rabbit defensin NP-1 gene was integrated into the poplar genome. The transformation efficiency is about 15.6%. Antimicrobial activity test showed that the extract of transgenic plants inhibited the growth of the tested microbes.

Animals↗

PubMed2001

Phytotoxicity of chlorinated aliphatics to hybrid poplar (Populus deltoides x nigra DN34).

Effects of a series of chlorinated ethenes and ethanes on hybrid poplar (Populus deltoides x nigra DN34) were assessed in laboratory experiments. Poplar cuttings were grown in sealed reactors with hydroponic solutions and were exposed to a chlorinated solvent for a period of two weeks. Exposure concentrations ranged from 0 to 0.4 mM for perchloroethylene to 0 to 8.4 mM for 1,1-dichloroethane. Effects were assessed by gravimetrically monitoring transpiration and measuring change in cutting mass. The zero-growth concentrations of the chemicals tested were 0.3 mM perchloroethylene, 0.9 mM trichloroethylene, 0.9 mM 1,1,2,2-tetrachloroethane, 2.0 mM 1,1,1-trichloroethane, 2.3 mM 1,1,2-trichloroethane, 4.8 mM trans-dichloroethylene, 5.6 mM 1,1-dichloroethylene, 6.0 mM cis-dichloroethylene, and 10.7 mM 1,1-dichloroethane. Adverse effects were found to increase with increasing number of chlorine atoms within a homologous series of ethenes or ethanes. Ethenes were more toxic than similarly chlorinated ethanes.

Biomass↗

PubMed2001

Isolation and characterization of a new peroxiredoxin from poplar sieve tubes that uses either glutaredoxin or thioredoxin as a proton donor.

A sequence coding for a peroxiredoxin (Prx) was isolated from a xylem/phloem cDNA library from Populus trichocarpa and subsequently inserted into an expression plasmid yielding the construction pET-Prx. The recombinant protein was produced in Escherichia coli cells and purified to homogeneity with a high yield. The poplar Prx is composed of 162 residues, a property that makes it the shortest plant Prx sequence isolated so far. It was shown that the protein is monomeric and possesses two conserved cysteines (Cys). The Prx degrades hydrogen peroxide and alkyl hydroperoxides in the presence of an exogenous proton donor that can be either thioredoxin or glutaredoxin (Grx). Based on this finding, we propose that the poplar protein represents a new type of Prx that differs from the so-called 2-Cys and 1-Cys Prx, a suggestion supported by the existence of natural fusion sequences constituted of a Prx motif coupled to a Grx motif. The protein was shown to be highly expressed in sieve tubes where thioredoxin h and Grx are also major proteins.

Amino Acid Sequence↗

PubMed2000

[Relationship between flooded situation and poplar growth on beach land of Yangtze River in Anhui].

Through the analysis on the dynamics of flooding and the annual ring series of poplar trees on the beach land of Yangtze river in Anhui in the period of 1989-1997, the related models on flooded situation and ring growth were built. The results showed that there existed significant differences in flooding time and depth on different elevations of beach land, which made a great influence on the annual ring growth of poplar trees. The maximal flooded depth was more important than flooded time for its influence on ring growth. In addition, the flooded situation in August and September of previous year had a significantly negative influence on the ring growth of current year. The beach land with a maximal flooded depth of more than 2 m was not suitable for high-productive plantation of timber. It is suggested that a little more dense plantation should be managed for the production of pulp materials.

China↗

PubMedDate not supplied

[Optimization model of spatial population structure: example of poplar moth laying eggs on leaves].

The authors analyze spatial distribution and survival of populations of poplar moth Litchcolletis populifoliella Tr. on its feeding plant--balsam poplar Populus balsamifera. Imago of the moth glue its eggs on the leaves thus determining the future location of their offspring on the host plant. Spatial distribution of eggs on leaf surface and distribution of leaves according egg numbers are not random. On the short distance from each egg the average number of eggs is less, than it should be in case of random distribution. While this distance increases up to some particular value the occurrence of eggs is higher than random. Thus, the eggs of moth are located by groups on the leaf surface. Within each group eggs are situated not very close to each other, this allowing larvae to lower competition for common resource. It is suggested that on the same feeding plant individuals have different interactions: competition, caused by limited quantity of resource and cooperation that is necessary to resist leaf defensive (antibiosis) reaction.

Animals↗

PubMed2003

[Relationship between photo-inhibition of photosynthesis and reactive oxygen species in leaves of poplars suffering root osmotic stress].

To know more about the photo-inhibition of photosynthesis under field conditions, its relationship with reactive oxygen species (ROS) in leaves of poplar clone seedlings was studied under osmotic stress conditions. With the increasing duration of osmotic stress and the enhancement of stress intensity, the ROS level, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity increased, while the activities of catalase (CAT) and ascorbate peroxidase (APX) decreased, resulted in the unbalanced ROS metabolism and intensified photo-inhibition. The inhibition of SOD activity by copper diethyldithiocarbamate or the accelerated generation of O2-. with methyl viologen (MV) could also induce the photo-inhibition. The decrease of the ability of poplar clone seedlings in scavenging H2O2 under osmotic conditions limited the dissipation of excess light energy and the role of photosynthetic apparatus in protecting against photo-inhibition through Mehler reaction. Photo-inhibition might be related to the accumulation of ROS.

Catalase↗

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↗

PubMedDate not supplied

Poplar pollen-related allergy in Ankara, Turkey: how important for patients living in a city with high pollen load?

The impact of high pollen load of particular plants on sensitized subjects is a topic of interest. We aimed to detect the clinical importance of poplar allergy in subjects with seasonal allergy living in Ankara, capital city of Turkey, having a high poplar pollen load. The subjects with seasonal allergy and demonstrating allergy to Populus alba in skin-prick tests (SPTs) (n = 20) underwent a specific nasal provocation test with P. alba allergen extract and were requested to fill in symptom-medication reports. During the same period, P. alba and Gramineae pollen counts were assessed in the city. Pollination for P. alba in Ankara for the year 2001 started in the 2nd week of March and terminated in the 1st week of May; 96.5% of subjects also had grass pollen sensitivities. By history, 85% of the subjects described mild symptoms in March and April, the expected pollinosis season for P. alba. Symptom and medication scores were higher in May and June than in March and April (p < 0.05). Allergy to P. alba pollen in patients with seasonal allergy causes mild symptoms where the dominant clinical presentation was demonstrated to be due to their additional Gramineae (grass) pollen allergy.

Adult↗

PubMed1995

Purification and properties of wall-bound endo-1, 4-beta-glucanase from suspension-cultured poplar cells.

A wall-bound endo-1, 4-beta-glucanase (EC 3.2.1.4) was obtained from a preparation of the cell walls of suspension-cultured poplar cells and purified to electrophoretic homogeneity by cation-exchange, hydrophobic, and gel-filtration chromatography. The molecular mass was estimated to be 47 kDa by SDS-PAGE and 48 kDa by gel filtration on Superdex 200 pg. The isoelectric point (pI) was 5.6. The purified enzyme catalyzed the endo-hydrolysis of carboxymethylcellulose with an optimal pH of 6.5, a Km of 1.2 mg ml-1, and a Vmax of 280 units. The purified enzyme specifically hydrolyzed the 1, 4-beta-glucosyl linkages of carboxymethylcellulose, phospho-swollen cellulose, lichenan, xylan and xyloglucan. The activity of the enzyme was strongly stimulated by cysteine-HCl. The N-terminal sequence of the enzyme was similar to that of an extracellular endo-1, 4-beta-glucanase found in suspension cultures of poplar cells and some homology was recognized to avocado fruit-ripening and bean abscission endo-1, 4-beta-glucanases.

Amino Acid Sequence↗

PubMedDate not supplied

[Inhalation of an extract from the leaf buds of the deltoid poplar during the early period following tonsillectomy].

To prevent inflammatory processes in the mucous membrane of the upper respiratory tract during early periods after tonsillectomy (2-7 days) the authors practiced inhalations of the extract of Eastern poplar leaf buds in 40 patients with chronic tonsillitis after the operation. The use of the extract of Eastern poplar leaf buds at early periods after tonsillectomy promotes abating of pains, speedy cicatrization of postoperative wounds, decrease of reactive inflammation in the pharynx and improvement of the general condition in the patients.

Adolescent↗

PubMed2025

Factors underlying a latitudinal gradient in the S/G lignin monomer ratio in natural poplar variants.

The chemical composition of wood plays a pivotal role in the adaptability and structural integrity of trees. However, few studies have investigated the environmental factors that determine lignin composition and its biological significance in plants. Here, we examined the lignin syringyl-to-guaiacyl (S/G) ratio in members of a Populus trichocarpa population sourced from their native habitat and conducted a genome wide association study to identify genes linked to lignin formation. Our results revealed many significant associations, suggesting that lignin biosynthesis is a complex polygenic trait. Additionally, we found an increase in the S/G ratio from northern to southern geographic origin of the trees sampled, along with a corresponding metabolic and transcriptional reprogramming of xylem cell wall biosynthesis. Further molecular analysis identified a mutation in a cell wall laccase genetically associated with higher S/G ratios that predominate in trees from warmer lower latitudes. Collectively, our findings suggest that lignin heterogeneity arises from an evolutionary process enabling poplar adaptation to different climatic challenges.

Populus↗

PubMed2026

Parent-of-origin effects on allelic expression bias in interspecific poplar hybrids.

In hybrid plants, phenotypic outcomes are governed by interactions between the two parental genomes. However, the mechanisms underlying the interplay of divergent regulatory networks from these genomes remain poorly understood. In this study, we compared gene-level and allele-specific expression patterns, as well as differentially enriched pathways between F₁ and complex backcross (CBC) lines derived from a natural interspecific hybrid population of Populus fremontii (Pf) and P. angustifolia (Pa). Metabolic differences between Pf and Pa which exhibit low and high levels respectively of phenylpropanoid-derived condensed tannins were leveraged. Using individualized transcriptome references, differential expression and clustering analyses revealed CBC-biased and F₁-biased expression for genes involved in phenylpropanoid metabolism and photosynthesis, respectively. Biased expression of these genes at the allele level was also observed in F1. At the whole-transcriptome level, Pa-biased genes predominated in F₁ hybrids, and Pa alleles displayed more conserved expression patterns than Pf alleles across examined samples. Further analyses indicated that allelic expression bias was significantly associated with parental origin, which could be driven by sequence variations in cis-regulatory elements and differences in CpG island length. Our findings demonstrate strong parent-of-origin effects on divergent regulatory networks governing gene expression in poplar hybrids and provide clues for strategic parental selection tailored to specific metabolic pathways of interest.

cis-regulation↗

PubMed2025

Comparative transcriptomics uncovers poplar and fungal genetic determinants of ectomycorrhizal compatibility.

Ectomycorrhizal symbiosis supports tree growth and is crucial for nutrient cycling and temperate and boreal ecosystems functioning. The establishment of functional ectomycorrhiza (ECM) first requires the association of compatible partners. However, host and fungal genetic determinants governing mycorrhizal compatibility are unknown. To identify such factors in poplar and its fungal associates, we mined existing and de novo tree and fungal transcriptional datasets. We identified co-expressed genes enabling ECM symbiosis at early and mature stages of the interaction. These sets of genes can be divided into general fungal-sensing and ECM-specific components. We highlight the importance of fungal modulation of plant JA-related defenses and the regulation of secretory pathways for ECM compatibility, including upregulation of key fungal small secreted proteins, the downregulation of plant secreted peroxidases, and the downregulation of plant cell wall remodeling proteins concomitantly with the upregulation of fungal glycosyl hydrolases acting on pectin. Not only gene regulation, but also its temporal scale and dynamics seem to play a crucial role for mycorrhizal compatibility. The expression profile of the host Common Symbiosis Pathway and nutrient transporters was also studied, revealing constitutive levels of expression and moderate upregulation in compatible ECM interactions. Overall, these results underscore the importance of novel biological functions during the establishment of ECM symbiosis, help us gain insights into the molecular events determining mycorrhiza compatibility, and serve as a data-rich transcriptomic resource to open new research questions in the field.

Mycorrhizae↗