Poplar Wood Research Articles

The Predictive Accuracy of Modulus of Elasticity (MOE) in the Wood of Standing Trees and Logs

The characterization of poplar wood assumes a strategic position to increase the competitiveness of the entire forest wood supply chain. From this aspect, the identification of wood quality represents a primary objective for researchers and private landowners. The quality of wood can be defined via traditional visual methods based on the experience of technicians or using traditional tools, such as incremental drills and sound hammers. The traditional properties of these traits, based only on visual characteristics, can outline a classification based on the macroscopic properties of wood with the aim of defining the volume of recoverable wood. However, this approach does not provide a good indicator of the physical or mechanical properties of wood. Mechanical tests of wood require the felling of trees with the correlated preparation of the specimens. A different solution to determine wood quality is based on the application of non-destructive technology (NDT). In this context, the aim of the present study was to determine the predictive accuracy of non-destructive analysis of the MOEd in standing trees and logs of a 22-year-old poplar clone and to examine the relationship with MOEs in sawn specimens. This relationship was also studied at three different stem heights. We non-destructively measured poplar trees and green logs using TreeSonic and Resonance Log Grader and compared the results with those obtained via a destructive method using a universal testing machine. The results showed that for clone I-214 poplar trees, the dynamic elastic moduli of standing trees and logs were validly correlated with the static elastic modulus. These results suggest that it is possible to evaluate the mechanical properties of poplar wood directly from standing trees using non-destructive techniques (NDT) and that this tool can be easily used to presort material in the forest.

LC/MS Q-TOF Metabolomic Investigation of Amino Acids and Dipeptides in Pleurotus ostreatus Grown on Different Substrates.

The well-established correlation between diet and health arouses great interest in seeking new health-promoting functional foods that may contribute to improving health and well-being. Herein, the metabolomic investigation of Pleurotus ostreatus samples grown on two different substrates (black poplar wood logs, WS, and lignocellulosic byproducts, LcS) revealed the high potential of such a mushroom as a source of bioactive species. The liquid chromatography/mass spectrometry combined with quadrupole time-of-flight (LC/MS Q-TOF) analysis allowed the identification of essential and nonessential amino acids along with the outstanding presence of dipeptides. Multivariate statistical models highlighted important differences in the expression of both classes of compounds arising from the growth of P. ostreatus strains on WS and LcS. The former, in particular, was correlated to an increased expression of carnitine-based amino acid derivatives and proline-based dipeptides. This finding may represent a potential strategy to drive the expression of bioactive compounds of interest to obtain enriched mushrooms or useful functional ingredients from them.

Performance Enhancement of the Poplar Wood Composites Biomimetic Mineralized by CaCO3.

Inspired by the natural matrix-mediated biomineralization, wood composites were prepared by vacuum impregnation using the gel effect of sodium alginate (SA) on calcium ions, which improved the mechanical properties, flame retardant, and smoke suppression properties of the wood composites. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed that the SA inducer had promoted the orderly deposition and directional crystallization of calcium carbonate (CaCO3) inside the wood cell walls and intercellular spaces. The density and weight gain rate of the biomimetic mineralized wood showed that CaCO3 effectively adhered to the interior of wood with SA as an inducer. The compressive and flexural strengths were 15.65% and 37.66% higher than those of the control, respectively. Thermogravimetric analysis (TG) proved that SA alleviated the thermal decomposition and complete combustion of the mineralized wood and improved the thermal stability. Microcalorimetry (MCC) and cone calorimetry (CONE) analyses revealed that the maximum heat release rate (HRR), total heat release (THR), and the total smoke production (TSP) rate of the mineralized wood was reduced by 59.51%, 48.52%, and 51.67%, respectively, compared with those of the control. This research demonstrates the in situ synthesis of CaCO3 within the cellular microstructure of the poplar which is using it as a biotemplate. With the enhancement of the flame retardant property and others, the wood composite biomimetic mineralized materials modified by CaCO3 and SA could be utilized more widely in the construction industry or other fields.

Tailored one-pot lignocellulose fractionation to maximize biorefinery toward controllable producing lignin nanoparticles and facilitating enzymatic hydrolysis

To achieve the global bio-based recycling economy with lignocellulosic biomass as feedstock, the additional value must be gained from both carbohydrates and lignin. In this study, a tailored one-pot lignocellulose fractionation, which was driven by ultrafast and recyclable microwave-assisted ternary deep eutectic solvent (DES, choline chloride: ethylene glycol: AlCl3) pretreatment, was developed to significantly reduce the natural “biomass recalcitrance”, promoting the production of lignin nanoparticles and facilitating enzymatic saccharification of cellulose. Confocal Raman microscopy (CRM) was applied to visually monitor the delignification in different cell walls during the DES pretreatments. Under the optimal condition (110 °C, 10 min), the glucose yield of the pretreated poplar via enzymatic saccharification reached 95.4 %, which was 5.8 times higher than that of the control. Advanced NMR characterizations of the DES lignin and control lignin fractions demonstrated that lignin polymers in the poplar wood had undergone the following structural changes, such as dehydration, depolymerization, condensation, and modification. Results showed that the regenerated DES lignin were nano-sized lignin, exhibiting the low molecular weights, narrow distribution (1.28<PDI<1.38) with controllable size (<100 nm), and excellent antioxidant activity. In short, the tailored one-pot DES fractionation will improve the enzymatic digestibility and facilitate the lignin valorization, which will further promote the economic and overall benefits of biorefinery.

Combined effects of multi-interfacial furfurylation and densification on mechanical-physical performances of fast-growing poplar wood

Combined effects of multi-interfacial furfurylation and densification on mechanical-physical performances of fast-growing poplar wood

Withdrawal Performance of Nails and Screws in Cross-Laminated Timber (CLT) Made of Poplar (Populus alba) and Fir (Abies alba).

Cross-laminated timber (CLT) can be used as an element in various parts of timber structures, such as bridges. Fast-growing hardwood species, like poplar, are useful in regions where there is a lack of wood resources. In this study, the withdrawal resistance of nine types of conventional fasteners (stainless-steel nails, concrete nails and screws, drywall screws, three types of partially and fully threaded wood screws, and two types of lag screws), with three loading directions (parallel to the grain, perpendicular to the surface, and tangential), and two layer arrangements (0-90-0° and 0-45-0°) in 3-ply CLTs made of poplar as a fast-growing species and fir as a common species in manufacturing of CLT was investigated. Lag screws (10 mm) displayed the highest withdrawal resistance (145.77 N), whereas steel nails had the lowest (13.13 N), according to the main effect analysis. Furthermore, fasteners loaded perpendicular to the grain (perpendicular to the surface and tangential) had higher withdrawal resistance than those loaded parallel to the grain (edge). In terms of the layer arrangement, fasteners in CLTs manufactured from poplar wood (0-45-0°) had the greatest withdrawal resistance, followed by CLTs manufactured from poplar wood in the (0-90-0°) arrangement, and finally, those made from fir wood in the (0-90-0°) arrangement. The fastener type had the most significant impact on the withdrawal resistance, so changing the fastener type from nails to screws increased it by about 5–11 times, which is consistent with other studies. The results showed that poplar, a fast-growth species, is a proper wood for manufacturing CLTs in terms of fastener withdrawal performance.

Modification of Poplar Wood via Polyethylene Glycol Impregnation Coupled with Compression

Wood permeability and compressibility are affected by cell wall structure and chemical composition. These properties can be improved by appropriate wood pretreatments. Low-density poplar wood was converted to a more dense structure by the following steps: First, lignin and hemicellulose were removed using a mixture of NaOH and Na2SO3. Second they were impregnated with polyethylene glycol (PEG, mean molecular weight of 1200), nano-SiO2, and a silane coupling agent at atmospheric temperature and pressure. Finally, impregnated wood was compressed at 150 °C. Results showed that the tracheid lumens on the transverse section of the compressed wood almost vanished. Specifically, the lumens in the wood cells, especially those that were compressed, were almost completely filled with PEG. In FTIR, the asymmetric absorption peaks of Si–O–Si at 1078–1076 cm−1 were clearly observed, which confirms the existence of bonding between nano-SiO2 and wood. The highest melting enthalpy and crystallization enthalpy showed a heat storage capacity of modified wood, which were 20.7 and 9.8 J/g, respectively. Such phase change capabilities may have potential applications in regulating the rate of change of room temperature. In summary, the modified wood could be utilized as material for construction to conserve energy.

Plastic regulates its co-pyrolysis process with biomass: Influencing factors, model calculations, and mechanisms

Co-pyrolysis of plastics and biomass can effectively improve the quality of bio-oil and solve the problem of plastic pollution. However, synergistic effect of co-pyrolysis on kinetics and the role of biomass H/Ceff in co-pyrolysis are still not conclusive. In this work, the co-pyrolysis synergistic effects of three different hydrogen-to-carbon ratio (H/Ceff) of biomass-rice husk (RH), sugarcane bagasse (SUG), and poplar wood (PW) with hydrogen-rich polypropylene (PP) were studied using a thermogravimetric method. The total synergy degree (φ) and the difference between experimental and theoretical weight losses (ΔW) were defined, and the activation energies of various experimental materials were calculated by the isoconversional method. The results showed that the addition of PP reduced the dependence of product species on biomass H/Ceff during co-pyrolysis. The synergistic effect of biomass and PP was related to biomass types, pyrolysis temperature, and mass ratio of biomass to PP. The mixture of SUG and PP showed positive synergistic effect at all mass ratios. Simultaneously, at the low temperature of pyrolysis, the synergistic effect is inhibited in all mixtures, which might be due to the melting of PP. Kinetic analysis showed that the activation energy could be reduced by 11.14–31.78% by co-pyrolysis with biomass and PP. A multi-step mechanism was observed in both the pyrolysis of a single sample and the co-pyrolysis of a mixture, according to Criado’s schematic analysis.

Effect of Impregnation with a Low-Concentration Furfuryl Alcohol Aqueous Solution on Hygroscopic Properties of Chinese Fir and Poplar Wood

Furfurylation with a low concentration of furfuryl alcohol (FA) promotes the improvement of the properties and the effectiveness of FA on cell–wall action without darkening the furfurylated wood to the point that it affects its applications. In this paper, the effects of furfurylation on the hygroscopicity and water uptake dimensional stability of poplar (Populus sp.) and Chinese fir (Cunninghamia lanceolata) were analyzed. Meanwhile, the distribution of FA resin, the relationship between wood and water, the change in pore size distribution, and the weight percentage gain and cell wall bulking coefficient of wood were also investigated. The results were as follows: (1) A low concentration of FA could better enter the cell walls of the Chinese fir than the poplar, as FA resin was almost cured in the secondary walls, cell corners, and compound middle lamellae when a 10% concentration of FA was applied to the Chinese fir and poplar. When the FA concentration was increased to 30%, there were no significant increases in the amount of FA entering the cell walls and the amounts of FA cured in the cell lumen of the poplar were greater than those of the Chinese fir. Meanwhile, the modification of cell walls was more suitable in poplar than in Chinese fir. (2) The pointed ends of the pit chambers and the pit apertures (800–1000 nm) in the poplar and the small pores of the pit membranes and the pit apertures (1–6 μm) in the Chinese fir were partially deposited by the FA resin, which formed new pores in the size ranges of 80–600 nm and 15–100 nm, respectively. The porosity of the poplar was greater than that of the Chinese fir, and the bulk density of the poplar was less than that of the Chinese fir before and after modification. (3) Furfurylation with a low concentration of FA was able to better reduce the equilibrium moisture content, improve the anti-swelling efficiency, and enhance the dimensional stability of the poplar wood compared to the Chinese fir. Furfurylation effectively reduced water uptake due to the hydrophobic property of the FA resin. The water uptake of the Chinese fir increased by 17%–19% in second cyclic water soaking when treated with FA with various concentrations, which indicated the loss and leaching of FA resin during the test. Low-field NMR was used to demonstrate that the furfurylation not only reduced the amount of water but also affected the combination state of bound and free water with wood. Thus, furfurylation at a low concentration is a feasible method by which to extend applications of furfurylated wood.

Effects of Aluminum Chloride Impregnating Pretreatment on Physical and Mechanical Properties of Heat-Treated Poplar Wood under Mild Temperature

The acid formed by thermal degradation of wood can autocatalyze its heat treatment. In this study, exogenous acid was introduced by impregnation into poplar wood to investigate its effect on the physical and mechanical properties of wood. Equilibrium moisture content (EMC), dimensional stability, mass loss (ML), color, modulus of rupture (MOR), and modulus of elasticity (MOE) of heat-treated poplar were tested under mild temperature (130–160 °C) for different pretreatment concentrations of aluminum chloride (AlCl3). The results show that the EMC of the heat-treated wood diminishes by 2.7%–47.8%, and dimensional stability improves significantly after AlCl3 impregnation pretreatment. The samples impregnated with 0.5 mol/L AlCl3 and heat treated at 160 °C achieved the best dimensional stability, which was better than for the samples only heat-treated at 220 °C. The color changed significantly as the impregnating concentration increased, achieving a color effect similar to that of wood only heat-treated at a high temperature such as 200 or 220 °C. Heat-treatment temperature under the same ML of wood samples was reduced, which also mitigated the reduction of MOR. MOE of heat-treated wood with 0.5 mol/L impregnation pretreatment was 11.4%–30.7% more than for samples heat-treated at 160–220 °C. After exogenous acidic AlCl3 impregnation pretreatment, the cell wall structure of the heat-treated wood was found to remain relatively intact. Thus, AlCl3 impregnating pretreatment exerted a substantial and beneficial effect on the physical and mechanical properties of poplar and achieved good performance of poplar wood treated at a mild temperature.

Effects of Inhibitors Generated by Dilute Phosphoric Acid Plus Steam-Exploded Poplar on Saccharomyces cerevisiae Growth

The pretreatment of lignocellulosic biomass is important for efficient bioethanol conversion, but causes undesirable by-products that inhibit microbial growth, conversely affecting the bioconversion efficiency. In this study, the main inhibitors derived from dilute phosphoric acid plus steam-exploded poplar wood were identified as 0.22 g/L furfural, 3.63 g/L acetic acid, 0.08 g/L syringaldehyde, etc., indicating the green nature and low toxicity of the pretreatment process. The effects of the three typical inhibitors (furfural, acetic acid, and syringaldehyde) on Saccharomyces cerevisiae 1517RM growth were analyzed and shown to prolong the lag phase of microbial growth to different degrees. In all the inhibitor groups, the ergosterol secretion was boosted, indicating low cell membrane fluidity and robustness of the strain to an adverse environment. The cell electronegativity and morphology of S. cerevisiae 1517RM also changed under different growth conditions, which was helpful for monitoring the physicochemical properties of cells. Furfural, acetic acid, and syringaldehyde had a synergistic effect on each other, providing an important reference to improving the subsequent ethanol fermentation process.

Analysis of Creep Properties and Factors Affecting Wood Plastic Composites.

Wood plastic composite (WPC) materials are mainly used as building slabs and load-bearing slabs, which will cause creep deformation, structural failure, and safety problems. Therefore, this work used high-density polyethylene and poplar wood flour as the main raw materials to prepare wood–plastic boards. The bending creep tests of wood–plastic sheets were carried out using an orthogonal test method. According to the creep test results, the influences of the WPC ratio molding temperature, pelleting temperature, coupling agent screw speed, and other technological factors on the creep properties of WPC composites under different loads are analyzed, and the influences of WPC creep properties on structural reliability are also analyzed. The results indicate that the wood–plastic ratio and screw speed are significant factors when the load is at 30% bending strength within the 24h creep test. When the load is at 50% bending strength, the wood–plastic ratio and molding temperature are the significant factors. When the load is at 70% bending strength, the wood–plastic ratio is the most significant factor. When the load is at 50% bending strength within the 240 h creep test, the wood–plastic ratio and molding temperature are significant factors. When the load is at 30% bending strength, the influence of each factor on the creeping variable is provided in the following descending order: wood–plastic ratio, molding temperature, granulation temperature, coupling agent, and screw speed, but none of them are significant factors.

UV kürlenmeli vernik uygulanmış karakavak odununda renk, parlaklık, salınımsal sertlik ve yüzeye yapışma direnci üzerine yapay yaşlandırmanın etkisi

Black poplar wood is used for the manufacture of furniture, paneling, and plywood. In this study, the relationship between 3 and 5 layers of UV system varnish applied to black poplar (Populus nigra L.) wood and artificial aging was investigated. In addition, before and after aging (252 and 504 hours), color parameters (∆E*, ∆L*, ∆a*, ∆b*, L*, a*, and b*), glossiness, pendulum hardness, and surface adhesion resistance (pull-off) tests were performed on varnished materials. According to the results obtained, for both varnish types, a decrease in surface adhesion resistance and L* value was determined with the increase of aging time after aging conditions with UVB-313 lamps, while increases were determined for a* and b* values. ∆E* values were found to be higher than that of the 3-layer application. In addition, it was determined that the measurements made in all directions and degrees glossiness for both varnish applications decreased with increasing aging time. It was observed that the pendulum hardness of the surfaces with 3 coats application was higher than that of the 5 coat application, while decreases were observed at the end of the 252 hours in both varnish types, while an increase was obtained at the end of the 504 hours. As a result, it is recommended to use this material in line with the usage areas according to the ambient conditions of the desired hardness resistance (space floor preference).

Identification of wood species and duration of exposure in weathered wood using guided wave propagation

ABSTRACT Nondestructive health monitoring of weathered timber structures in outdoor applications is a critical safety and quality control task. This study proposes a guided Lamb wave propagation approach for identifying the type of wood and estimating the duration of exposure in different wood species under artificial weathering. Accordingly, alder, fir, oak, and poplar wood specimens underwent accelerated weathering conditions. The intact and degraded wood specimens were assessed via the Lamb wave propagation experiments, and different sensory features were extracted and used to train machine learning models. The decision tree and random forest classification were performed to identify the type of wood and the duration of exposure to weathering. The results of the decision tree classification indicated that the extracted wave-based features could identify the type of wood species with an accuracy of 82.5%. The wave features could also classify the duration of exposure to weathering with a maximum accuracy of 75%. Higher classification performance was obtained using the random forest model where the wood species and exposure duration were classified with an accuracy of 85% and 81.25%, respectively. Overall, the guided Lamb wave propagation exhibited the potential for in-situ assessment and species identification of weathered wood in outdoor conditions.

Performance improvement of poplar wood based on the synergies of furfurylation and polyethylene glycol impregnation

Abstract Fast-growing wood usually exhibits dimensional instability and inferior mechanical strength, which severely obstructs its wide application. To improve the dimensional stability and mechanical strength, biomass-derived furfuryl alcohol combined with polyethylene glycol (PEG) was vacuum-impregnated into wood hierarchical structures, causing cell wall bulking and porosity reduction. Furfural resin and PEG distributed in cell lumina, cell walls and middle lamella regions indicated by analyses of scanning electron microscope and fourier transform infrared spectroscopy. Wood porosity was generally reduced and the specific surface area decreased by over 65% analyzed by the nitrogen absorption. Consequently, wood hydrophobicity and dimensional stability were highly improved, and the water absorption and volumetric change decreased by over 55% and 78%. The flexural strength and modulus elasticity were improved by over 49% and 46%. Furfural resin helped the fixation of PEG in wood and significantly reduced PEG leaching. PEG with flexible linear molecular structure formed interpenetrating polymer network in wood hierarchical structures with furfural resin and reduced self-crosslinking of furfural resin. Accordingly, the impact toughness of compound modified wood increased by 39% compared with solely furfurylated wood. This study provided efficient and sustainable concepts to facilitate better industrialized application of wood furfurylation and improve service value of fast-growing wood.

LigninGraphs: lignin structure determination with multiscale graph modeling

Lignin is an aromatic biopolymer found in ubiquitous sources of woody biomass. Designing and optimizing lignin valorization processes requires a fundamental understanding of lignin structures. Experimental characterization techniques, such as 2D-heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra, could elucidate the global properties of the polymer molecules. Computer models could extend the resolution of experiments by representing structures at the molecular and atomistic scales. We introduce a graph-based multiscale modeling framework for lignin structure generation and visualization. The framework employs accelerated rejection-free polymerization and hierarchical Metropolis Monte Carlo optimization algorithms. We obtain structure libraries for various lignin feedstocks based on literature and new experimental NMR data for poplar wood, pinewood, and herbaceous lignin. The framework could guide researchers towards feasible lignin structures, efficient space exploration, and future kinetics modeling. Its software implementation in Python, LigninGraphs, is open-source and available on GitHub.Graphical abstract

Engineering Curcumin Biosynthesis in Poplar Affects Lignification and Biomass Yield.

Lignocellulosic biomass is recalcitrant toward deconstruction into simple sugars mainly due to the presence of lignin. By engineering plants to partially replace traditional lignin monomers with alternative ones, lignin degradability and extractability can be enhanced. Previously, the alternative monomer curcumin has been successfully produced and incorporated into lignified cell walls of Arabidopsis by the heterologous expression of DIKETIDE-CoA SYNTHASE (DCS) and CURCUMIN SYNTHASE2 (CURS2). The resulting transgenic plants did not suffer from yield penalties and had an increased saccharification yield after alkaline pretreatment. Here, we translated this strategy into the bio-energy crop poplar. Via the heterologous expression of DCS and CURS2 under the control of the secondary cell wall CELLULOSE SYNTHASE A8-B promoter (ProCesA8-B), curcumin was also produced and incorporated into the lignified cell walls of poplar. ProCesA8-B:DCS_CURS2 transgenic poplars, however, suffered from shoot-tip necrosis and yield penalties. Compared to that of the wild-type (WT), the wood of transgenic poplars had 21% less cellulose, 28% more matrix polysaccharides, 23% more lignin and a significantly altered lignin composition. More specifically, ProCesA8-B:DCS_CURS2 lignin had a reduced syringyl/guaiacyl unit (S/G) ratio, an increased frequency of p-hydroxyphenyl (H) units, a decreased frequency of p-hydroxybenzoates and a higher fraction of phenylcoumaran units. Without, or with alkaline or hot water pretreatment, the saccharification efficiency of the transgenic lines was equal to that of the WT. These differences in (growth) phenotype illustrate that translational research in crops is essential to assess the value of an engineering strategy for applications. Further fine-tuning of this research strategy (e.g., by using more specific promoters or by translating this strategy to other crops such as maize) might lead to transgenic bio-energy crops with cell walls more amenable to deconstruction without settling in yield.

Prediction of surface roughness of CO2 laser modified poplar wood via response surface methodology

Due to the advantages of short treatment period, no wastewater and oil produced, the CO2 laser is applied as an environment friendly thermal treatment for wood materials to improve the wood properties, such as appearance, color and wettability, among others. However, the morphological features of treated wood surface are also changed, which have negative effects on wooden product properties. To reveal the change tendency of surface roughness during laser irradiation, the common indexes of average roughness (Ra) and mean peak-to-valley height (Rz) were chosen to evaluate the surface roughness. The response surface methodology was selected to arrange the experiments and analyze the influences of laser parameters on surface roughness. The results showed that the poplar wood got rougher with the increased laser power, but the surface roughness decreased with increased feed speed and path spacing, due to the total heat absorption varied under different combination of laser parameters. The ANOVA results showed that the selected quadratic models for Ra∥, Rz∥, Ra⊥and Rz⊥were significant due to the values of probability value (“Prob>F”) less than 0,05. In this case, all the input laser parameters were also the significant model terms for variation of surface roughness. The values of correlation coefficient were very close to 1, which meant the selected quadratic models could give accurate prediction of surface roughness for laser treated wood. Therefore, it is of great significance to predict the surface roughness of the modified wood surface scientifically and to guide the selection of reasonable modification process parameters.

PtrWOX13A Promotes Wood Formation and Bioactive Gibberellins Biosynthesis in Populus trichocarpa.

WUSCHEL-related homeobox (WOX) genes are plant-specific transcription factors (TFs) involved in multiple processes of plant development. However, there have hitherto no studies on the WOX TFs involved in secondary cell wall (SCW) formation been reported. In this study, we identified a Populus trichocarpa WOX gene, PtrWOX13A, which was predominantly expressed in SCW, and then characterized its functions through generating PtrWOX13A overexpression poplar transgenic lines; these lines exhibited not only significantly enhanced growth potential, but also remarkably increased SCW thicknesses, fiber lengths, and lignin and hemicellulose contents. However, no obvious change in cellulose content was observed. We revealed that PtrWOX13A directly activated its target genes through binding to two cis-elements, ATTGATTG and TTAATSS, in their promoter regions. The fact that PtrWOX13A responded to the exogenous GAs implies that it is responsive to GA homeostasis caused by GA inactivation and activation genes (e.g., PtrGA20ox4, PtrGA2ox1, and PtrGA3ox1), which were regulated by PtrWOX13A directly or indirectly. Since the master switch gene of SCW formation, PtrWND6A, and lignin biosynthesis regulator, MYB28, significantly increased in PtrWOX13A transgenic lines, we proposed that PtrWOX13A, as a higher hierarchy TF, participated in SCW formation through controlling the genes that are components of the known hierarchical transcription regulation network of poplar SCW formation, and simultaneously triggering a gibberellin-mediated signaling cascade. The discovery of PtrWOX13A predominantly expressed in SCW and its regulatory functions in the poplar wood formation has important implications for improving the wood quality of trees via genetic engineering.

Study on infection behavior and characteristics of poplar wood dyed by Lasiodiplodia theobromae.

The technology of dyeing wood by microorganisms is a kind of pollution-free and sustainable wood dyeing technology. To achieve fast and rich dyeing of Lasiodiplodia theobromae on the surface of poplar wood, tyrosinase and tricyclazole were used as induction factors in this experiment. The results showed that L. theobromae had a better induction effect in the cross-section of poplar wood and induced with tricyclazole. The surface color of poplar ranged from light yellow dyeing to gray and brown, the chromatic aberration of the cross-section of wood was above 44.5 NBS, and the infected area was over 50%, while the dyed parts of radial and tangential sections of wood were only on the surface of the wood after 30 days of infection. The induced infection of L. theobromae on poplar wood had little effect on the chemical components of poplar and had good colorfastness to washing and light. Therefore, microbial dyeing of wood showed a beneficial application prospect in the field of wood dyeing.