Lignin Content Research Articles

Fabrication of biodegradable polyvinyl alcohol-based plastics toward technical lignin valorization

The fabrication of composite materials from lignin has attracted increasing attention to reducing the dependence of petrochemical-based resources on carbon neutrality. However, the low content of lignin in the biocomposites remains a challenge. Herein, industrial lignin is fractionated by an organic solvent to reduce its structural heterogeneity. Subsequently, the fractionated lignin samples are integrated with polyvinyl alcohol (PVA) to fabricate plastics characterized by uniform thickness and smooth surfaces. The resultant composite films exhibit tensile strength and strain up to 75 MPa and 1050%, respectively, which surpass state-of-the-art lignin-based bioplastics. The mechanism investigations reveal that the enhanced mechanical properties are due to the internal non-covalent interactions derived from the hydroxyl groups of lignin and PVA. Notably, the PVA/lignin films are biodegradable after 92 days' burial in soil. This study paves the way for the rational design of lignin-based biodegradable polymers as sustainable alternatives to conventional plastics.

A novel approach for quantitative determination of lignin content in tobacco via multiCP/MAS NMR spectroscopy

AbstractAs the main structural component of tobacco cell wall, lignin content is an important factor affecting the safety of tobacco smoking. However, it is time‐consuming to quantify lignin by conventional wet chemical analysis methods. In this work, a 13C multiCP/MAS NMR spectral analysis method for tobacco lignin was established. The multiCP/MAS NMR sequence was optimized for tobacco lignin. The optimized nuclear magnetic sequence parameters were 9 CP cycles of 1.5 ms, repolarization time of 0.7 s, and a total acquisition time of 130 min. Subsequently, TMSP was used as the internal standard substance to establish the working curve, and the correlation coefficient was 0.9946. The relative standard deviation (RSD, n = 5) was 3.26%. This method was applied to the determination of lignin content in different types of tobacco samples. The relative error in the determination of lignin content by this method did not exceed 4.46% compared to the results of the chemical method. The results showed that the 13C multiCP/MAS NMR spectral analysis method had the advantages of accuracy and rapidity, which provided a new technical means for the quantitative study of tobacco cell wall substances.

CCT39-COMT1/BGLU18-2 module promotes lignin biosynthesis in poplar

Lignin is a crucial constituent of cell walls and plays a pivotal role in plant growth and development. However, the transcriptional regulatory network governing lignin biosynthesis is not fully understood. In this study, we observed that PpnCCT39 overexpression resulted in greener stems, larger basal diameters, and increased stem dry weight. Additionally, the secondary xylem of lines overexpressing PpnCCT39 was wider, had larger xylem fiber cell areas, and thicker cell walls, compared to those of wild-type plants. Furthermore, PpnCCT39 overexpression led to elevated lignin content and enhanced the rigidity of secondary cell walls. RNA-seq and ChIP-seq association analyses identified 826 potential regulatory target genes of PpnCCT39 that were upregulated and expressed in 1-month-old PpnCCT39 overexpression lines. Gene enrichment analyses revealed enrichment in pathways related to cell wall formation, xylem and phloem development, and the phenylpropanoid pathway. Two genes involved in lignin biosynthesis, PagCOMT1 and PagBGLU18–2, exhibited significantly increased expression in stems of lines overexpressing PpnCCT39, as demonstrated by high FPKM values and RT-qPCR results. Further investigations using yeast one-hybrid, dual-luciferase assays, and electrophoretic mobility shift assays demonstrated that PpnCCT39 directly activates the transcription of PagCOMT1 and PagBGLU18–2, thereby promoting lignin biosynthesis. This study elucidated the transcriptional regulatory mechanism of PpnCCT39 in poplars and revealed its role in activating the expression of key lignin biosynthesis genes. PpnCCT39 facilitates lignin biosynthesis and secondary growth processes, offering a novel theoretical framework for modulating lignin biosynthesis and enhancing timber yield through molecular design.

Bio-organic fertilizer affects secondary cell wall biosynthesis of Dendrocalamus farinosus by inhibiting the phenylpropanoid metabolic pathway

Bamboo, as a timber plant, holds significant environmental and economic value. Dendrocalamus farinosus is particularly valuable as it serves both as a source of bamboo shoots and timber, offering high yield, strong disease resistance, and superior fiber quality. Our previous study demonstrated that bio-organic fertilizers promoted the growth of D. farinosus and significantly altered the cellulose and lignin content, key components of the secondary cell wall in culms. However, the underlying regulatory mechanisms remain unclear. In this study, we used metabolomic and transcriptomic analyses to uncover the potential mechanisms by which bio-organic fertilizers affect the secondary cell wall biosynthesis in D. farinosus. A total of 1,437 metabolites were identified, with 20 differential metabolites significantly enriched in the phenylpropanoid metabolic pathway in bamboo shoots (7 upregulated; 13 downregulated). We identified 8,075 differentially expressed genes in bamboo shoots, including 72 genes potentially involved in lignin and flavonoid biosynthesis (6 upregulated; 66 downregulated). In internodes, we identified 5,324 differentially expressed genes, including 83 genes potentially involved in secondary cell wall biosynthesis (43 upregulated; 39 downregulated). Quantitative real-time PCR (qRT-PCR) validated the expression patterns of 8 key genes in internodes. The results suggest that bio-organic fertilizers may affect secondary cell wall biosynthesis in internodes by inhibiting the phenylpropanoid metabolic pathway in D. farinosus shoots. Our study offers insights into the efficient utilization of bamboo and lignocellulosic biomass, serving as a valuable resource for future research.

Combined physiological, biochemical, and multi-omic analyses provide insight into the cause of differential browning in early and late harvested fresh-cut yams

Tissue browning reduces the cosmetic quality of fresh-cut yams and poses a marketing problem. The degree of browning of fresh-cut yams varies depending on when they are harvested. In this study, transcriptomic and metabolomic analyses were conducted in yams harvested in September (DHPS) and October (DHPO) to determine the mechanisms responsible for the browning of fresh-cut yams. Results showed that the browning index, total phenol and lignin content, polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), 4-coumarate: CoA Ligase(4CL), and cinnamic acid-4-hydroxylase(C4H) activity in fresh-cut DHPO yams were lower than they were in fresh-cut DHPS yams. Flavonoids and catalase (CAT) activity remained consistently higher during storage in DHPO yams than in DHPS yams. The browning of fresh-cut DHPO yams was mitigated by the regulation of the expression of genes and the abundance of metabolites associated with phenolic metabolism, phytohormones, and signal transduction, as well as sucrose and starch metabolism. The level of browning enzyme activity in DHPO yams was significantly lower than it was in DHPS yams. Our study provides a basis for the selection of optimum harvest date for yams that will undergo fresh-cut processing.

Structural Characterisation of Raw and Acid-Pretreated Invasive Plant Biomass (Ludwigia hexapetala and Ricinus communis)

This study focused on the structural characterization of Raw and Acid-Pretreated Invasive Plant Biomass (Ludwigia hexapetala and Ricinus communis) and its impact on biofuels production. Raw and acid-pretreated biomass samples were characterized using various techniques, including FTIR, SEM, TEM, XRD, TGA, and BET surface area analysis. Acid pretreatment significantly altered the biomass structure, increasing cellulose content, decreasing lignin content, and enhancing surface area and porosity. The results obtained in this analysis highlight the crucial role of structural features in determining biofuel potential. This study demonstrates the feasibility of utilizing invasive plants as sustainable feedstocks for biofuel production and underscores the importance of structural analysis in optimizing bioethanol production processes.

Crosslinked lignin starch copolymer as a sustainable and thermally stable drilling fluid controller

Fluid loss is a well-known challenge of drilling operations. In this work, a novel sustainable starch-lignin-based polymer was synthesized for possible use in drilling fluid applications. The X-ray photoelectron spectroscopy (XPS) analysis confirmed that kraft lignin was crosslinked with starch via ether covalent bonds. The X-ray diffraction (XRD) analysis confirmed the loss of crystallinity in starch and emerging of new amorphous structures in crosslinked starch-lignin (CSL) polymers after crosslinking with lignin. The incorporation of lignin and new covalent ether bonds improved the thermal stability of starch. The CSL had a rougher surface morphology, higher hydrophilicity, and significantly higher water absorption than starch. CSL-2, with its higher lignin content, demonstrated higher hydrophilicity, better water absorption capacity, and thermal stability than CSL-1. The rheology analysis of the CSL-2 polymer suggested that crosslinking starch with lignin would increase G′ more than G" and reduce tan δ of the polymer solution, resulting in more elastic properties and more stability against the angular frequency. Due to its improved swelling, thermal, and rheological properties as compared to native starch, the produced sustainable lignin-starch copolymer could be used as a new viscosity and rheology modifier, such as a fluid loss controller for oil extraction from wells.

Disruption of aldehyde dehydrogenase decreases cell wall-bound p-hydroxycinnamates and improves cell wall digestibility in rice.

In grass cell walls, ferulic acid (FA) serves as an important cross-linker between cell wall polymers, such as arabinoxylan (AX) and lignin, affecting the physicochemical properties of the cell walls as well as the utilization properties of grass lignocellulose for biorefinering. Here, we demonstrate that hydroxycinnamaldehyde dehydrogenase (HCALDH) plays a crucial role in the biosynthesis of the FA used for cell wall feruloylation in rice (Oryza sativa). Bioinformatic and gene expression analyses of aldehyde dehydrogenases (ALDHs) identified two rice ALDH subfamily 2C members, OsHCALDH2 (OsALDH2C2) and OsHCALDH3 (OsALDH2C3), potentially involved in cell wall feruloylation in major vegetative tissues of rice. CRISPR-Cas9 genome editing of OsHCALDH2 and OsHCALDH3 revealed that the contents of AX-bound ferulate were reduced by up to ~45% in the cell walls of the HCALDH-edited mutants, demonstrating their roles in cell wall feruloylation. The abundance of hemicellulosic sugars including arabinosyl units on AX was notably reduced in the cell walls of the HCALDH-edited mutants, whereas cellulose and lignin contents remained unaffected. In addition to reducing cell wall-bound ferulate, the loss of OsHCALDH2 and/or OsHCALDH3 also partially reduced cell wall-bound p-coumarate and sinapate in the vegetative tissues of rice, whereas it did not cause detectable changes in the amount of γ-oryzanol (feruloyl sterols) in rice seeds. Furthermore, the HCALDH-edited mutants exhibited improved cell wall saccharification efficiency, both with and without alkaline pretreatment, plausibly due to the reduction in cell wall cross-linking FA. Overall, HCALDH appears to present a potent bioengineering target for enhancing utilization properties of grass lignocellulose.

Abundance of Human Pathogenic Microorganisms in the Halophyte Salicornia europaea L.: Influence of the Chemical Composition of Shoots and Soils

Salicornia europaea L. is a halophilic plant species belonging to Chenopodiaceae, whose shoots are used as a vegetable. Since the shoots can be eaten raw, the objective of the present study was to investigate possible controls on the abundance of human pathogenic microorganisms (HPMOs) in the shoots as a health risk. For this reason, the molecular-chemical composition of shoots, site-specific soil organic matter (bulk and rhizosphere), and soil pH and salinity were analyzed. Plant and soil samples were taken from two test sites with differing salinity levels in France (a young and an old marsh). We hypothesized that the chemical traits of plants and soils could suppress or promote HPMOs and, thus, serve as risk indicators for food quality. The chemical traits of shoots and bulk and rhizosphere soil were measured through thermochemolysis using gas chromatography/mass spectrometry (GC/MS). The densities of cultivable HPMOs (Salmonella enterica, Escherichia coli, and Listeria monocytogenes) were determined in plant shoots, rhizosphere soil, and bulk soil using selective media. Negative correlations between lignin content in the shoots and the abundance of S. enterica, as well as between lignin content in bulk soil and the abundance of E. coli, are explained by the lignin-based rigidity and its protective effect on the cell wall. In the shoot samples, the content of lipids was positively correlated with the abundance of E. coli. The abundance of E. coli, S. enterica, and L. monocytogenes in bulk soil decreased with increasing soil pH, which is linked to increased salinity. Therefore, soil salinity is proposed as a tool to decrease HPMO contamination in S. europaea and ensure its food safety.

Unraveling the dynamics of lignin chemistry on decomposition to understand its contribution to soil organic matter accumulation

Abstract Aims Plant inputs are the primary organic carbon source that transforms into soil organic matter (SOM) through microbial processing. One prevailing view is that lignin plays a major role in the accumulation of SOM. This study investigated lignin decomposition using wood from different genotypes of Populus tremula as the model substrate. The genotypes naturally varied in lignin content and composition, resulting in high and low lignin substrates. Methods The wood was inoculated with fresh soil and decomposition was interpreted through mass loss and CO2 produced during a 12-month lab incubation. Detailed information on the decomposition patterns of lignin was obtained by Two-dimensional Nuclear magnetic resonance (2D NMR) spectroscopy on four occasions during the incubations. Results The lignin content per se did not affect the overall decomposition and ~ 60% of the mass was lost in both substrates. In addition, no differences in oxidative enzyme activity could be observed, and the rate of lignin decomposition was similar to that of the carbohydrates. The 2D NMR analysis showed the oxidized syringyl present in the initial samples was the most resistant to degradation among lignin subunits as it followed the order p-hydroxybenzoates > syringyl > guaiacyl > oxidized syringyl. Furthermore, the degradability of β–O–4 linkages in the lignin varied depending on the subunit (syringyl or guaiacyl) it is attached to. Conclusions Our study demonstrates that lignin contains fractions that are easily degradable and can break down alongside carbohydrates. Thus, the initial differences in lignin content per se do not necessarily affect magnitude of SOM accumulation.

Optimization of Microwave-Assisted Organosolv Cellulose Recovery from Olive-Tree Pruning with Three Different Solvents

Research studies for cellulose recovery from lignocellulosic materials are essential in order to propose sustainable alternatives to harness residual biomasses, solving problems caused by their abundance and inadequate use. In this study, olive-tree pruning biomass has been subjected to different pretreatments with different organosolvents (acetone, ethanol, and γ-valerolactone) with microwave radiation assistance. The effect of operating parameters has been studied, considering specific ranges of variables values according to each experimental design but, in any case, located in the ranges of 33–67% (chemical compound concentration), 130–170 °C (temperature), 5–30 min (reaction time), and 1/20–1/5 (solid/liquid ratio, s/L). Based on the R2 and R2adj values (mostly above 0.97), the experimental data were adequately adjusted to four selected response variables: post-solids cellulose and lignin content apart from removal percentages of both structural components. The optimization process resulted in post-treatment solids with meaningful cellulose yields (higher than 84.7%) and reduced lignin content (lower than 4.2%). The best results were obtained using 66.5% acetone (155 °C, 8.4 min and s/L = 1/19), involving greater material deconstruction, a high percentage of delignification (96.7%), not very significant cellulose loss (29.4%), and a post-treatment solid consisting almost exclusively of cellulose (≈99%).

Integrating QTL mapping and transcriptome analysis to provide molecular insights into gynophore-pod strength in cultivated peanut (Arachis hypogaea L.).

Gynophore-pod strength is one of important mechanical properties that affect mechanized harvesting quality in peanut. Yet its molecular regulation remains elusive. We measured gynophore-pod strength across three environments using a recombinant inbred line (RIL) population derived from a cross between Yuanza9102 and Xuzhou68-4, followed by QTL mapping. Lines with extreme gynophore-pod strength from the RILs were selected to perform anatomical analysis and transcriptome analysis to elucidate the underlying molecular mechanisms governing gynophore-pod strength. Both genotypic factor and environments affected gynophore-pod strength significantly, and its broad sense heritability (h2 ) was estimated as 0.77. Two QTLs that were stable in at least two environments were detected. qGPS.A05-1 was mapped 4cM (about 1.09Mb) on chromosome A05, and qGPS.B02-1 was mapped 3cM (about 1.71Mb) on chromosome B02. Anatomical analysis showed higher lignin content in lines with extreme high gynophore-pod strength compared to those with extreme low gynophore-pod strength. Additionally, comparative transcriptome analysis unveiled that phenylpropanoid biosynthesis was the main pathway associated with high gynophore-pod strength. Further, we predicted VJ8B3Q and H82QG0 as the candidate genes for qGPS.A05-1 and qGPS.B02-1, respectively. The two stable QTLs and their associated markers could help modify gynophore-pod strength. Our findings may offer genetic resources for the molecular-assisted breeding of new peanut varieties with improved mechanized harvesting quality.

Pengaruh Konsentrasi Natrium Hidroksida dan Waktu Pemasakan Terhadap Penurunan Kadar Lignin Menggunakan Kulit Edamame (Glycin Max (L) Merill) dengan Proses Soda

The increase in demand for pulp and kertas raises awareness of the problem of kayu hutan as the primary raw material for pulp and kertas production. As a result, an alternative to kayu is required. One non-kayu tanaman that has the potential to be used as an alternative raw material in pulp production is edamame kulit (Glycin max (L) merrill), which is slowly brewed or baked such that it can cause environmental problems. Kulit edamame has a relatively high selulosa content of 2.3% to 13.1%. This study aims to understand the effects of pemasakan and the concentration of natrium hydroxide on the lignin pulp from kulit edamame using the soda process. The best method for this study is to use NaOH concentrations of 0.7%, 0.9%, and 1.78%, 1.82, and 1.86 percent at pemasakan times (100, 115, 125, 135, 145 menit) has lignin tertinggi kadar of 2,0376% and lignin terendah kadar of 0,9000%. The purpose of this study is to determine the pulp quality that is obtained from the soda process using NaOH concentration and the best combination of NaOH concentration and pemasakan time in the production of pulp from Kulit Edamame. The results of the study show that as the concentration of NaOH increases, the amount of lignin will decrease. This is because increasing the concentration of pemasakan's lignin can increase the amount of delignification and the amount of lignin that degrades will result in better pulp. And the longer the pemasakan time, the longer the lignin kadar will flow, resulting in a pulp that is more putih and has better quality.

Hydrogen sulfide enhances the disease resistance of ginger to rhizome rot during postharvest storage through modulation of antioxidant response and nitric oxide-mediated S-nitrosylaion

Postharvest pathogenic infestation leads to the quality deterioration in ginger industry. Hydrogen sulfide (H2S), as an emerging potential postharvest protectant, could enhance disease resistance. This study investigated the antifungal role of H2S against Fusarium solani during ginger postharvest storage. The results showed that H2S restricted widespread infection by F. solani in gingers and have direct antimicrobial activity against F. solani in vitro, inhibiting mycelial growth and spore germination. H2S improved endogenous H2S accumulation, increased the activities of POD, CAT and SOD, and facilitated the removal of excess ROS. It also promoted the lignin, total phenolic and flavonoid contents, while boosting the activities of PAL, C4H and 4CL, and up-regulating the expression of ZoPAL, ZoC4H and Zo4CL. Moreover, H2S increased endogenous NO levels through the NR and NOS pathways. Notably, the endogenous SNO content was increased, the GSNOR activity as well as expression of GSNOR were down-regulated by H2S treatment. These effects were reversed by hypotaurine (HT), a scavenger of H2S. Together, these results indicated that H2S induces the disease resistance in postharvest ginger storage via enhancing antioxidant and defense capacity, regulating phenylpropane metabolism, inducing NO production and mediating NO-dependent S-nitrosylation modification. These results provide guidance for the application of H2S during the storage of ginger.

Synthesis of lignin-based elastomers via ARGET ATRP: Exceptional mechanical strength, adhesion, and self-repair properties

In this study, ARGET ATRP method was employed to graft two functional monomers from lignin, resulting in the synthesis of a series of Lignin-graft-poly(lauryl methacrylate-co-cyclohexyl methacrylate) (Lignin-g-P(LMA-co-CMA)) copolymers with varying feed ratios and lignin content. The results demonstrate that by varying the feed ratios of the two monomers, the glass transition temperature of lignin-based elastomers can be finely tuned. Importantly, the introduction of lignin and CMA imparts outstanding mechanical properties to the lignin-based elastomers, with a maximum tensile strength reaching 20.13 MPa. The elastic recovery rate of the lignin-based elastomers was exceptional, with the elastic recovery coefficient (ER) of Lignin0.52-PLMA500 exceeding 90 %. Adhesion tests on various substrates revealed the remarkable adhesion properties of these copolymers. In particular, Lignin0.52-PLMA500 exhibited strong adhesion on both iron plate and glass substrate, with adhesion strengths of 2.23 MPa and 2.33 MPa, respectively. Notably, Lignin0.52-PLMA500 demonstrated significant self-healing ability after damage. Furthermore, the lignin-based elastomer exhibited exceptional ultraviolet absorption performance. In conclusion, the incorporation of lignin opens up a novel pathway for the development of high-strength and tough lignin-based elastomers. However，more effort still needs to be paid for increasing the adhesive properties aiming to explore more potential application field.

Microbial communities during the composting process of Agaricus subrufescens and their effects on mushroom agronomic and nutritional qualities.

Tunnel composting technology for preparing Agaricus subrufescens cultivation media can achieve a higher biological efficiency (BE) and a lower contamination rate (CR). However, this technology lacks in-depth and systematic study. In the present study, the changes in the microbiome and microbial metabolic functions were surveyed using metagenomic analysis. The physicochemical parameters, agronomic properties and nutritional qualities were also evaluated. Results showed that the contents of cellulose, hemicellulose and lignin dropped to 10.18, 11.58, 27.53%, respectively at the end of composting. The tunnel composting technology led to significant increases in crude protein content (32.56%) and crude fiber content (13.68%). Variations of physicochemical characteristics led to different successions of microbial communities. Bacteria manifested significantly higher abundance than fungi. Firmicutes, Actinobacteriota, Chloroffexi and Deinococcota were the predominant bacterial phyla. Ascomycota and Basidiomycota were the dominant fungal phyla in the thermophilic phase. Pseudonocardia, Truepera, and Thermopolyspora were positively correlated with the yield of A. subrufescens. In addition to TN, most of the physicochemical properties were significantly correlated with fungal communities in the thermophilic phase. The metabolisms of carbohydrate, amino acid and energy were the primary enrichment pathways. These findings deepen the understanding of microbial communities composition during the composting of A. subrufescens substrates. Moreover, this study provides a basis for improving tunnel composting technology.

Synergistic and Antagonistic Effects of Mixed-Leaf Litter Decomposition on Nutrient Cycling.

Understanding decomposition patterns of mixed-leaf litter from agroforestry species is crucial, as leaf litter in ecosystems naturally occurs as mixtures rather than as separate individual species. We hypothesized that litter mixtures with larger trait divergence would lead to faster mass loss and more balanced nutrient release compared to single-species litter. Specifically, we expected mixtures containing nutrient-rich species to exhibit synergistic effects, resulting in faster decay rates and sustained nutrient release, while mixtures with nutrient-poor species would demonstrate antagonistic effects, slowing decomposition. We conducted a mesocosm experiment using a custom wooden setup filled with soil, and the litterbag method was used to test various leaf litter mixtures. The study involved leaf litter from six agroforestry tree species: three species from humid highland regions and three from semi-arid regions. Treatments included three single-species leaf litter mixtures, three two-species mixtures, and one three-species mixture, based on the sampling region. Species included Calliandra calothyrsus (Ca), Croton megalocarpus (Cr), Grevillea robusta (G), Alnus acuminata (A), Markhamia lutea (M), and Eucalyptus globulus (E). Decay rate constants (k) were estimated using non-linear least-squares regression and observed mass loss was compared to predicted values for mixed-species litter treatments to assess synergistic and antagonistic effects. A two-way linear mixed-effects model was employed to explain variation in mass loss. Results indicate positive non-additive effects for leaf litter mixtures including nutrient-rich species and negative non-additive effects for mixtures including nutrient-poor species. The mixture of Ca + Cr + G had positive non-additive or synergistic effects as it decomposed faster than its corresponding single-species litter. Leaf litters with higher lignin content, such as A + M + E and Ca + Cr + G, exhibited less lignin release compared to what would be expected based on individual litter types, demonstrating antagonistic effects. These findings highlight that both litter nutrient constituents and litter diversity play an important role in decomposition processes and therefore in the restoration of the degraded and nutrient-depleted soils of Rwanda.

An Efficient In Vitro Regeneration Protocol and the Feature of Root Induction with Phloroglucinol in Paeonia ostii.

Paeonia ostii, a plant of substantial economic significance, continues to face constraints in achieving large-scale propagation. In vitro propagation offers a promising avenue for the production of disease-free plants and the genetic transformation of peonies to instill novel traits. However, significant challenges persist in tissue culture, particularly with regards to the reproduction coefficient of shoots and the rooting process. This study reports an efficacious protocol for P. ostii micropropagation, focusing on in vitro root development facilitated through the application of phloroglucinol (PG). Furthermore, the study unveils the molecular signature of P. ostii during in vitro root development. The results indicate that the modified Y3 medium (Y3M), supplemented with 1 mg/L 6-benzyladenine (BA) and 0.1 mg/L α-naphthaleneacetic acid (NAA), is optimal for adventitious bud induction, achieving a 96.67% induction rate and an average of 16.03 adventitious shoots per sample. The highest elongation percentage (92.15%) and the longest average shoot length (3.87 cm) were obtained with Y3M containing 0.3 mg/L BA and 0.03 mg/L NAA. Additionally, the optimal medium for inducing root formation in P. ostii was identified as WPM supplemented with 3 mg/L indole-3-butyric acid (IBA) and 100 mg/L phloroglucinol (PG). Lignin content detection, microscope inspection, and molecular signature results demonstrated that PG enhanced lignin biosynthesis, thereby promoting in vitro rooting of P. ostii.

The PtobZIP55-PtoMYB170 module regulates the wood anatomical and chemical properties of Populus tomentosa in acclimation to low nitrogen availability.

Poplar plantations are often established on nitrogen-poor land, and poplar growth and wood formation are constrained by low nitrogen (LN) availability. However, the molecular mechanisms by which specific genes regulate wood formation in acclimation to LN availability remain unclear. Here, we report a previously unrecognized module, basic region/leucine zipper 55 (PtobZIP55)-PtoMYB170, which regulates the wood formation of Populus tomentosa in acclimation to LN availability. PtobZIP55 was highly expressed in poplar wood and induced by LN. Altered wood anatomical properties and increased lignification were detected in PtobZIP55-overexpressing poplars, whereas the opposite results were detected in PtobZIP55-knockout poplars. Molecular and transgenic analyses revealed that PtobZIP55 directly binds to the promoter sequence of PtoMYB170 to activate its transcription. The phenotypes of PtoMYB170 transgenic poplars were similar to those of PtobZIP55 transgenic poplars under LN conditions. Further molecular analyses revealed that PtoMYB170 directly bound the promoter sequences of lignin biosynthetic genes to activate their transcription to increase lignin concentrations in LN-treated poplar wood. These results suggest that PtobZIP55 activates PtoMYB170 transcription, which in turn positively regulates lignin biosynthetic genes, increasing lignin deposition in the wood of P. tomentosa in the context of acclimation to LN availability.

Characterizing the chemistry of artificially degraded Scots pine wood serving as a model of naturally degraded waterlogged wood using1H–13C HSQC NMR

Chemically and biologically degraded Scots pine wood was prepared as a model material for the research on new conservation agents for waterlogged archeological wood. In this study, the model wood was characterized using a 2D1H–13C solution-state NMR technique without derivatization, isolation, or extraction to assess the effect of applied degradation processes on its chemical composition and structure. The results clearly show how the two artificially degraded model wood types are chemically different. Biological decay by the brown-rot fungus Coniophora puteana caused degradation of wood polysaccharides, with heavy depletion in arabinan, mannan, and galactan, along with an increase in the cellulose's reducing ends (i.e., lowering the degree of polymerization) and partial deacetylation of mannan. The fungus cleaved roughly one-fifth of the β-aryl ethers in lignin, leading to a broadening effect on the lignin aromatic unit contours; other lignin sidechains were left untouched. Chemical degradation by NaOH hydrolysis resulted in a depletion in mannan, galactan, and glucan, as well as efficient deacetylation of mannan. It also decreased lignin content, causing changes in its structure; minor β-aryl ether cleavage along with substantial phenylcoumaran cleavage were evident. Detailed knowledge about the chemical composition and structure of artificially degraded model pine wood obtained in this research is necessary to understand the reactivity of these wood types with chemicals used for their conservation. This research will help explain the differences in the stabilization effectiveness observed between these wood types treated during conservation and understand the stabilization mechanisms, thus contributing to developing new, more effective conservation agents for wooden artifacts of Cultural Heritage.