From Populus tremuloide

Figure 6-3. A gelatinous layer (G-layer) is formed on the inside of the S2 layer in tension wood fibers from Populus tremuloides. Courtesy of Geoff Daniel, Swedish University of Agriculture Sciences. With permission...

In this, it resembles the promoter of the xylem-specific PtrCesAl gene from Populus tremuloides, which is very similar to PttCesA3-l and PttCesA3-2, and which was shown to be activated by tension stress in transgenic tobacco expressing the promoter-P-glucuronidase (GUS) fusions (Wu et al. 2000). 

A further pathway of biosynthesis of salicylic acid (97) may involve its formation from the unusual alicyclic acid (102) wtiich is found in the glucosides tremulacin (101) and salicortin (100) which have been isolated from Populus tremuloides and Salix purpurea... 

The particular wood species we chose for this study is aspen (Populus tremuloides), which is plentiful in Canada and in the northern U.S.A. The chemical composition we found to be glucan 53.4%, xylan 14.9%, total carbohydrate 79.0%, lignin 17.1% and extractives 3.8%. We would expect total fermentable sugars of about 56% in this sample of aspen in anhydro form (Timell has reported about 60% in another sample (15)) which upon hydrolysis would yield about 1,250 lb wood sugars per ton of wood (dry basis), from the stoichiometry. Theoretical conversion of this sugar to ethanol would yield 640 lb or 81.1 gallons of anhydrous... 

FIGURE 9 Release of CO2 by complete photolytic degradation of sterile leachate from leaves of the riverine popular tree (Populus tremuloides), grown under ambient atmospheric C02 and doubled C02 concentrations, after one week of microbial decomposition. 

Triazine herbicides are primarily effective in controlling herbaceous weeds. A notable exception is the use of granular hexazinone for controlling woody invaders such as oaks (Quercus spp.) or aspen (Populus tremuloides) in conifer stands on medium- and fine-textured soils in the South or in boreal forests. Hexazinone also is used in the Maritime Provinces of Canada for controlling woody and herbaceous growth in natural Christmas tree stands (Townsend, 1995a). The impact of herbaceous plant cover is somewhat different from that of woody plant competitors, so control strategies on various forest conifer sites may differ. 

Prasad, R. and J.C. Feng (1990). Spotgun-applied hexazinone Release of red pine (Pinus resinosa) from quaking aspen (Populus tremuloides) competition and residue persistence in soil. Weed Technol., 4 371-375. 

Table 6.2.2. Yields on nitrobenzene and cupric oxide oxidation products from Norway spruce (Picea abies) and aspen (Populus tremuloides) woods...

Fligh concentrations of air pollutants are known to kill many annual plants and trees. This amounts to a coarse biological indicator. Less severe exposures can cause premature senescence (early leaf drop) of sensitive species of trees and shrubs [39], which can be used as an indicator [40]. For example, the aspen poplar, Populus tremuloides, drops its leaves after exposure to as little as 0.34 ppm of sulfur dioxide for 1 hr. Early leaf drop slows tree growth, which can be qualitatively assessed by examining the growth ring widths from the tree cores. Several leaf drops in quick succession can kill trees or annual plants. 

The quaking aspen tree (Populus tremuloides) is a common tree in North America that is used for its timber. The wood-rotting pathogen Phellinus tre-mulae causes significant economic losses of this tree. Although the sesqui-terpenoid metabolites such as tremulenolide A (5.89) have a carbon skeleton that is isomeric with the lactaranes, some doubts have been expressed on its biosynthetic origin from farnesyl diphosphate. 

Propionic acid can also be made from the hemicellu-loses in wood.215 These have few other uses. Steam-exploded Populus tremuloides was hydrolyzed enzymatically, then the hydrolysate treated with Propionibacterium acidipropionici to produce 18 g/L of propionic acid. Because this organism is inhibited by the product, various methods have been developed to remove it as formed. Use of ditridecylamine in oleyl alcohol with a hollow-fiber membrane gave a higher yield, final product concentration, and purity, at the same time that the production of acetate and succinate were reduced in a run of 1.5 months.216 The acid was recovered with aqueous sodium hydroxide using a second hollow-fiber membrane. 

By contrast, the 3D structural analysis of a bona fide CAD has been reported only for the Arabidopsis AtCAD4 and AtCAD5, as two other reports of putative CADs from Saccharomyces cerevisiae and Populus tremuloides (aspen) are not currently considered as CADs proper. Saccharomyces cerevisiae does not produce metabolites in the phenylpropanoid pathway, thereby making it unclear as to why this specific metabolic role was being contemplated. In addition, the putative sinapyl aldehyde dehydrogenase (SAD) from aspen was not established to have the specific function claimed (see Davin etal and Anterola and Lewis " for a full discussion). 

Ge, L. and VL. Chiang (1996). A full length cDNA encoding trans-cinnamate 4-hydroxylase from developing xylem of Populus tremuloides. Plant Physiol 112, 861. 

PETERS, D.J., CONSTABEL, C.P., Molecular analysis of herbivore-induced condensed tannin synthesis cloning and expression of dihydroflavonol reductase from trembling aspen (Populus tremuloides). Plant J., 2002,32, 701-712. 

HARUTA, M., MAJOR, I.T., CHRISTOPHER, M.E., PATTON, J.J., CONSTABEL, C.P., A Kunitz trypsin inhibitor gene family from trembling aspen Populus tremuloides Michx.) cloning, functional expression, and induction by wounding and herbivory. Plant Molec. Biol, 2001,46, 347-359. 

The study area is situated near Rouyn-Noranda, about 600 km to the north-west of Montreal, Canada (48°14 N, 79°01 W). Three sites were sampled at a downwind distance of 0.5, 2 and 8 km from the Horne copper smelter. At each site, soil samples were collected under three trembling aspen Populus tremuloides Michx) of similar age (< 30 years old). The soils developed in postglacial lake sediments of silt texture to form Luvisols, according to the Canadian System of Soil Classification (Soil Classification Working Group, 1998). The extent of soil contamination received through the atmospheric deposition of metals represents the main difference between the three sites as other characteristics were kept constant (e.g. climate, parent material, slope, aspect, etc.). For a more detailed description of the sites, see Seguin et al. (2004). 

The sampling was performed at the end of September 1998. At each of the three sampling sites, three Populus tremuloides were uprooted carefully (for a total of nine trees). The three trees are the field replicates used to establish site variability. All soil samples are taken from the upper B horizon (15-20 cm under the organic-mineral interface). This horizon enables the collection of enough roots to provide sufficient rhizosphere mass for chemical analyses, while being deep enough to avoid the lack of contrast between the rhizosphere and the bulk soil that is found in organic horizons. The root diameter was between 0.5 mm and 1 cm. 

In this paper we report our efforts to characterize the solid residues produced in a series of experiments with the semicontinuous extraction of Populus tremuloides (aspen wood) in supercritical me-thanol iSi, at temperatures ranging from 250 to 350°C (Supercritical Extraction residues or SCE residues), by using wet chemistry and chromatographic, thermogravimetric and spectral methods such as DRIFTS 2 > and ESCA. ... 

Trembling aspen wood (Populus tremuloides Michx.) was reduced to a powder in a Hurricane Pulverizer. Samples were prepared from extracted pulverized wood by ball-milling for 10 days in a rotating ceramic mill equipped with an air-conditioning unit which prevented the temperature of the contents of the mill from rising above ambient. Digestion of the samples with cellulase was done with a mixture of Schizophyllum commune and Trichoderma reesei culture filtrates at 30°C for 3 days. 

Isol. from the partial acid hydrolysates of white spruce (Picea glauca), western hemlock (Tsuga heterophylla), jute fibre, maritime pine (Pinus pinaster), aspen (Populus tremuloides) hemicelluloses. 

Rg. 7.14 The numbers of different potential foodplants for Papilio glaucus (of the 20 favorites) which occur at different latitudes along the transect presented in Figs 7.12 and 7.13. The foodplant species are numbers from top to bottom (i.e.. Quaking aspen, Populus tremuloides, is 1, etc.). The plant transition zone is represented by shading. 

Wu L., Joshi C.P., and Chiang V.L. 2000. A xylem-specific cellulose synthase gene from aspen Populus tremuloides) is responsive to mechanical stress. Plant J. 22 495-502. 

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