Successful <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> with apple <Emphasis Type="Italic">SPDS</Emphasis> gene

The problem of salinized soils has become one of the most serious constraints to agricultural and forest productivity. With the purpose of enhancing salt stress tolerance of Populus tomentosa, we transformed this tree species with spermidine synthase （SPDS） genes derived from an apple by an Agrobacterium-mediated method. Four transgenic clones were confu＇med by PCR and Southern blot analysis. As well, the expression of introduced SPDS genes was analyzed by real-time quantitative PCR.     

In vitro regeneration of <Emphasis Type="Italic">Populus tomentosa</Emphasis> from petioles

A reliable in vitro regeneration procedure for Populus tomentosa is a prerequisite for its trait improvement through genetic transformation. We established a systematic protocol for indirect regeneration of P. tomentosa using in vitro petioles of Chinese poplar cultivar ‘fasta-3’. A high frequency of callus induction (>97 %) was obtained from isolated petioles cultured on the modified 1/2MS basal medium supplemented with 0.5 mg/L ZT and 1.0 mg/L NAA, and the tested calli were subsequently plated on 1/2MS basal medium supplemented with 0.25 mg/L BA, 0.25 mg/L ZT, 0.25 mg/L NAA, 0.01 mg/L TDZ, and 0.5 mg/L KT for efficient regeneration of shoots after being cultured for 6 weeks. The regenerated shoots were vigorously rooted on the tested media supplemented with 1.0 mg/L IBA and 0.5 mg/L NAA. These results can facilitate genetic transformation of P. tomentosa for trait improvements in future.     

Comparison and early selection of new clones in <Emphasis Type="Italic">Populus tomentosa</Emphasis>

In our study, two experimental plantations, respectively, with 24 and 32 new clones of P tomentosa, were established in Weixian County, Hebei Province and Wuzhi County, Henan Province using a completely randomized block design. A comparative study was conducted on the continuous 5-year-old height and diameter at breast height （DBH） of new clones in the two plantations. As well, based on genetic correlation over the years of testing of these clones, a preliminary study of early selection was carried out. Results indicate that the growth traits of the new clones in Weixian were better than those in Wuzhi. The traits show weak correlation between the two plantations. In some stands, the height, DBH and seedling volume of 5-year-old clones presented statistically significant differences among clones. In both plantations, the new clones showed over 0.6 repeatability of height, DBH and volume, as well as larger coefficients of variation （CV）. The fact that these clones achieved the largest repeatability and CV in the second year suggests that these traits are highly controlled by heredity. Thus, based on the growth traits of the second year, the new clones B305, B307, B303, H75, BT18, BT17 and 21J-1 were considered suitable in Weixian. In Wuzhi, the new clones had variable repeatability and CVs in various years and their correlation of growth traits among different years was not high. We conclude that early selection of new clones was not feasible in Wuzhi.     

Response of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> and <Emphasis Type="Italic">Acacia mangium</Emphasis> kraft pulp in different ECF bleaching options

In this study, the response of Eucalyptus camaldulensis and Acacia mangium kraft pulp to different options of ECF bleaching was investigated. Oxygen-delignified pulps of both species having similar kappa number (c.a. 12) were used. Both the pulps were prebleached using conventional ClO₂ stage (D₀), combined use of ClO₂ and O₃ (DZ), hot acid treatment before D₀ (A_hotD₀) and hot acid treatment before (DZ) i.e., A_hot(DZ), hot ClO₂ treatment (D_HT) and A_hot followed by D_HT (A_hotD_HT). All prebleached pulps were finally bleached to 90%+ ISO brightness using D₁ option. The overall benefits of other options were not considerable compared to D₀ and (DZ). From the ClO₂ consumption point of view, for a certain species, the option A_hot(DZ) was the best. Instead of D₁ in final bleaching, pressurized hydrogen peroxide (PO) was also investigated in the case of D₀ and (DZ) prebleached pulps. (PO)-bleached pulp produced higher brightness stability but lower viscosity compared to D₁.     

Establishment of cell suspension line of <Emphasis Type="Italic">Populus tomentosa</Emphasis> Carr.

Leaves of fine Populus tomentosa genotype TC152 were used as explants to establish cell suspension lines. The effects of plant growth regulators on callus induction and establishment of cell suspension lines were studied. The callus induction rate was the highest on a MS solid medium supplemented with 1.0 mg·L^-1 2,4-D. A cell suspension line could be obtained by inoculating calli which were not subcultured into a MS liquid medium supplemented with 1.5 mg·L^-1 2,4-D. The best subculture medium was MS ＋ 0.8 mg＇L-1 2,4-D ＋ 30 g·L^-1 sucrose with a subculture cycle of seven days.     

TCF Bleaching of Populus tomentosa Kraft Pulps with H2O2 Pretreatment under Acid Condition

The process of peroxide bleaching of Populus tomentosa kraft pulp with H2O2 pretreatment under acid condition was studied. The variations of pulp characteristics such as brightness, Kappa number and viscosity during the peroxide bleaching process were discussed and the concept of the A/B value was presented for the first time. The results show that acid pretreatment with H2O2 is essential to improve pulp brightness and avoid viscosity loss. The conclusion is reached that the A/B value has great influence on pulp properties when the total amount of peroxide used in the bleaching process is 2%–5%. Pulp with a high viscosity and brightness can be obtained when A/B is about 0.15.     

Constitutive expression of sense &; antisense <Emphasis Type="Italic">PtAP3</Emphasis>, an <Emphasis Type="Italic">AP3</Emphasis> homologue gene of <Emphasis Type="Italic">Populus tomentosa</Emphasis>, affects growth and flowering time in transgenic tobacco

To analyze the function of PtAP3, an APETALA3 （AP3） homologue gene isolated from Populus tomentosa Carr., the full length sequence （1797 bp） and a fragment （870 bp） of PtAP3 were fused to a CaMV 35S promoter of pBI121 to generate the sense and antisense constructs of PtAP3. These constructs were transformed into tobacco by Agrobacterium infection of leaf disks and selection on kanamycin medium. Some sense and antisense transgenic tobacco plants were obtained by PCR and Southern blot analysis. Great phenotypic differences in transgenic tobacco plants were observed. Almost all of sense PtAP3 to transgenic tobaccos showed a higher growth rate than those of antisense transformants and a few developed pregnancy earlier than wild type seedlings and antisense transformants under the same conditions.     

New piezoelectric moduli of wood: <Emphasis Type="Italic">d</Emphasis><Subscript>31</Subscript> and <Emphasis Type="Italic">d</Emphasis><Subscript>32</Subscript>

This article reports the piezoelectric moduli of wood d ₃₁, d ₃₂, and d ₃₆. The piezoelectric moduli of wood d ₃₁ and d ₃₂ have not been previously reported, although there has been much research on the d ₁₄ and d ₂₅ moduli of wood. The moduli d ₃₁, d ₃₂, and d ₃₆ were measured carefully because their absolute values were considerably smaller than those of d ₁₄ and d ₂₅. For Softwoods, d ₃₆ values were mostly negative, whereas the values for hardwoods had either positive or negative values. The other moduli, d ₃₁ and d ₃₂, were a mixture of positive and negative values in softwoods and hardwoods. The existence of d ₃₁ and d ₃₂ suggests the presence of an electrical polarity of the cellulose crystal in the fiber direction of the wood. The polarities of d ₃₁ and d ₃₂ became clear from wood in the outer part of the trunk, where the crystallinity of cellulose is large and the alignment of the crystals becomes parallel to the fiber direction.     

Feeding performance of <Emphasis Type="Italic">Clostera fulgurita</Emphasis> on three clones of <Emphasis Type="Italic">Populus deltoides</Emphasis>

Poplar leaf defoliator, Clostera fulgurita (Walker) larvae were reared on three Populus deltoides clones (PL1, PL5 and PL7) in the laboratory. The nutritional indices were computed for working out the relationship between food consumption and growth rate of 3rd, 4th and 5th instar larvae on three clones. The result showed that the consumption index (CI), approximate digestibility (AD), growth rate (GR), relative growth rate (RGR) and efficiency of conversion of ingested food (ECI) decreased with the increase in the age of the larvae. Efficiency of conversion of digested food (ECD) increased with increase in age of the larvae. GR and RGR varied significantly, indicating that larval development was enhanced on PL1 as compared to PL5 & PL7. The values of AD, ECI and ECD were not affected by the different clones. Feeding and growth indices could be useful to define a defoliation prediction model.     

Study on the changes in surface characteristics of <Emphasis Type="Italic">Populus tomentosa</Emphasis> due to thermo-hydro-process

The effects of high temperature, moisture, and mechanical action during the thermo-hydro-mechanical (THM) processing, on the changes in surface properties of poplar, namely, surface color, roughness, wettability, and microstructure, were investigated in this study. The correlation between observed changes in surface properties and chemical characteristics was also analyzed. Poplar woods with high moisture content were compressed using different pressures at temperature of 160 °C for four different periods. The wood surfaces became darker and smoother, and their surface free energy decreased significantly after the THM process. THM process markedly reduced surface hygroscopicity compared to the control wood. The cell lumens of THM wood became narrow with increasing compression ratio due to the enhancing high pressure. Collapse and fractures of cell walls developed during THM treatment. Furthermore, results indicated that a series of chemical reactions in different components of wood took place during THM process, such as degradation of hemicelluloses, condensation of lignin, and decomposition of extractives. In turn, these chemical modifications contributed to the darkening of color as well as the reduction of wettability and surface free energy of THM wood.     

At5g54160 gene encodes <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> 5-hydroxyconiferaldehyde <Emphasis Type="Italic">O</Emphasis>-methyltransferase

The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k _cat/K _m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM⁻¹·min⁻¹. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s). Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March 24–27, 2007     

High level expression of glucose-6-phosphate dehydrogenase gene <Emphasis Type="Italic">PsG6PDH</Emphasis> from <Emphasis Type="Italic">Populus suaveolens</Emphasis> in <Emphasis Type="Italic">E. coli</Emphasis>

In order to investigate the functions of the gene PsG6PDH and the mechanisms underlying freezing tolerance of Populus suaveolens, the recombinant expression vector pET-G (pET30a-G6PDH), which contained full encoding region of PsG6PDH gene, was established. The recombinant was identified by lawn-PCR and double enzyme digestion and then transformed into expression host XA90 and induced by isopropyl-â-D-thiogalactoside (IPTG) to express 100 kD polypeptide of G6PDH fusion protein. The results showed that the expressed amount of the fusion protein culminated after 1 mmol&#8226;L^–1 IPTG treatment for 4 h and that pET-G product was predominately soluble and not extra-cellular secreting.     

Model of leaf energy distribution and its experimental validation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> Carr.

Leaf temperature of a plant is the result of heat transfer between the plant and its environment. There are many factors that can affect leaf temperature, such as the solar radiation energy, environmental temperature, wind velocity, evaporation on the leaf surface, photosynthesis, respiration and so on, which have different effects on the temperature of leaves. In first instance, we analyzed the heat transfer on leaves of Populus tomentosa Carr. theoretically and constructed a model of energy distribution. We then validated the model by analyzing seven different kinds of one-year-old P. tomentosa leaves experimentally. The result shows that solar radiation is the main energy input and the dominant ways of thermal diffusion are heat transfer between the upper and lower leaf surfaces and evaporation from the leaf surface.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.     

Structure and Function of <Emphasis Type="Italic">Populus deltoides</Emphasis> Agroforestry Systems in Eastern India: 2. <Emphasis Type="Italic">Nutrient dynamics</Emphasis>

Nutrient concentrations in plant and soil and their rates of cycling in poplar (Populus deltoides)-based agroforestry systems were studied at Pusa, Bihar, India. The nutrient concentrations in the standing biomass of the crop were more than those in tree, whereas the nutrient contents showed the reverse trend. Soil, litter and vegetation accounted for 80.3–99.5, 0.1–5.0 and 0.4–14.7%, respectively, of the total nutrients in the system. Considerable reduction (40–54%) in concentration of nutrients in leaves occurred during senescence. The uptake of nutrients by vegetation, and also by different components with and without adjustment for internal recycling, were calculated separately. Annual transfer of litter nutrient to the soil by vegetation was 37.3–146.2 N, 5.6–17.9 P and 25.0–66.3 K kg ha⁻¹ year⁻¹ in young (3-year-old) and mature (9-year-old) plantations. Turnover rate and time for different nutrients ranged between 0.86–0.99 year⁻¹ and 1.01–1.16 years, respectively. Compartmental models for nutrient dynamics have been developed to represent the distribution of nutrient contents and net annual fluxes within the system. This study shows that the poplar-based agroforestry system can be sustainable in terms of soil nutrient status.     

Experimental study on characteristic curves of restoring forces of <Emphasis Type="Italic">Populus alba</Emphasis> var. <Emphasis Type="Italic">pyramidalis</Emphasis>

Static tests under cyclic loading were carried out on Populus alba var. pyramidalis to determine its characteristic curves of     

Effect of thermo-hydro-mechanical densification on microstructure and properties of poplar wood (<Emphasis Type="Italic">Populus tomentosa</Emphasis>)

This study aimed at developing a thermo-hydro-mechanical (THM) processing to compress poplar wood and investigating the effects of high temperature, moisture, and pressure during the THM processing on the changes in microstructure, porosity, mechanical properties, and dimensional stability of compressed poplar wood. The variations in these properties were correlated and their mathematical relations were determined. Poplar woods with high moisture content were compressed using different pressures at a temperature of 160 °C for different periods. The compression level was characterized by the volume compression ratio (CR), which is defined as the ratio of the compression volume and the original volume of sample before and after THM processing. The obtained results indicated that the high pressure of THM process caused the collapsing of wood cell lumens and the developing of a certain amount of fractures in the cell wall. The damage level of wood cells increased with increasing pressure and time. Moreover, the pressure narrowed the cell lumens, which decreased significantly the pore volume in wood substrate. The pore size distribution shifted from the level of macropores to those of mesopores and micropores after THM process. The THM process created superior mechanical property, especially for those with higher CR. Besides, it was revealed that the process decreased dramatically the set recovery of treated woods and improved their dimensional stability. A significant improvement was achieved in terms of the mechanical and physical properties of compressed poplar wood via the structural reformation during the THM process.     

Bioremediation of CCA-treated wood by brown-rot fungi <Emphasis Type="Italic">Fomitopsis palustris</Emphasis>, <Emphasis Type="Italic">Coniophora puteana</Emphasis>, and <Emphasis Type="Italic">Laetiporus sulphureus</Emphasis>

This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.An erratum to this article can be found at     

The behaviour of the species mingling index<Emphasis Type="Italic"> M</Emphasis><Subscript><Emphasis Type="Italic">sp</Emphasis></Subscript> in relation to species dominance and dispersion

Ecosystem conservation plays an increasingly important role in forest management. The value for such conservation has been directly linked to high diversity of species and structure within systems. In the past, forestry inventory practices have concentrated on aspects that were primarily required for timber management. Now, however, much interest has arisen in measures that will indicate higher or lower diversity. The interspersion of trees of different species reflects diversity at a local level and may serve as an important indicator for the simplification of a forest or woodland system. This article shows that the mingling index M_sp is robust in describing the spatial dispersion of plants; some guidelines for interpreting M_sp are provided.     

Osmoregulators in <Emphasis Type="Italic">Hymenaea courbaril</Emphasis> and <Emphasis Type="Italic">Hymenaea stigonocarpa</Emphasis> under water stress and rehydration

The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 × 5 × 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation—E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g^?1 of the residue for H. courbaril and 0.27 mmol g^?1 of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.