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Lignin is the second most abundant renewable biopolymer on earth after cellulose. It is being used in many industrial applications due to its abundance. In the present study, lignin was isolated from the stems of Leucaena leucocep...
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Lignin is the second most abundant renewable biopolymer on earth after cellulose. It is being used in many industrial applications due to its abundance. In the present study, lignin was isolated from the stems of Leucaena leucocephala (Lam.) de Wit., a high biomass yielding plant using acidic dioxane under N-2 atmosphere. Structural characterization of isolated dioxane lignin (DL) was performed by analytical techniques: UV, FT-IR, H-1 NMR and C-13 NMR. Their monolignol content was determined by nitrobenzene oxidation followed by HPLC-MS/MS analysis. The data was compared with commercial alkali lignin (AL). The results showed that DL is of hardwood guaiacyl-syringyl (GS) type, whereas AL is softwood type with more guaiacyl units and trace amounts of p-hydroxyphenyl units (H). Thermogravimetric analysis (TGA) of DL showed two stage thermal degradation profile similar to AL. The DTG(max) for DL and AL were found in the second major loss event of second stage of TGA at 424 degrees C and 404 degrees C, respectively. Differential scanning calorimetry (DSC) study exhibited the glass transition temperatures (T-g) at 132 degrees C and 122 degrees C for DL and AL, respectively. The results from thermal stability studies suggest that dioxane lignin isolated from the "miracle tree" (subabul) can be exploited in various thermoplastic industrial applications.
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Sequential fractionation of extractive-free maize stems was carried out using two mild alkaline extractions (0.5 and 2. M NaOH, 20 °C, 24. h) before and after endoglucanase treatment. This procedure provided two lignin-carbohydra...
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Sequential fractionation of extractive-free maize stems was carried out using two mild alkaline extractions (0.5 and 2. M NaOH, 20 °C, 24. h) before and after endoglucanase treatment. This procedure provided two lignin-carbohydrate fractions (LC1 and LC2) recovered after each alkali treatment. LC1 and LC2 contained 39% and 8% of the total lignin amount, respectively. These two fractions contained structurally distinct lignin molecules. While the content of resistant interunit bonds in lignin was 77% in LC1, it was increased up to 98% in LC2. Not unexpectedly, both alkali-soluble fractions contained substantial amount of p-coumaric and ferulic acids ether-linked to lignins. These results outline heterogeneity of maize stem lignins related to fractionation of grass materials.
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Metabolic fluxes represent the functional phenotypes of biochemical pathways and are essential to reveal the distribution of precursors among metabolic networks. Although analysis of metabolic fluxes, facilitated by stable isotope...
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Metabolic fluxes represent the functional phenotypes of biochemical pathways and are essential to reveal the distribution of precursors among metabolic networks. Although analysis of metabolic fluxes, facilitated by stable isotope labeling and mass spectrometry detection, has been applied in the studies of plant metabolism, we lack experimental measurements for carbon flux towards lignin, one of the most abundant polymers in nature. We developed a feeding strategy of excised Arabidopsis stems with 13C labeled phenylalanine (Phe) for the analysis of lignin biosynthetic flux. We optimized the feeding methods and found the stems continued to grow and lignify. Consistent with lignification profiles along the stems, higher levels of phenylpropanoids and activities of lignin biosynthetic enzymes were detected in the base of the stem. In the feeding experiments, 13C labeled Phe was quickly accumulated and used for the synthesis of phenylpropanoid intermediates and lignin. The intermediates displayed two different patterns of labeling kinetics during the feeding period. Analysis of lignin showed rapid incorporation of label into all three subunits in the polymers. Our feeding results demonstrate the effectiveness of the stem feeding system and suggest a potential application for the investigations of other aspects in plant metabolism. The supply of exogenous Phe leading to a higher lignin deposition rate indicates the availability of Phe is a determining factor for lignification rates.
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Stems are important for plants to grow erectly. In stems, sclerenchyma cells must develop secondary cell walls to provide plants with physical support. The secondary cell walls are mainly composed of lignin, xylan and cellulose. D...
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Stems are important for plants to grow erectly. In stems, sclerenchyma cells must develop secondary cell walls to provide plants with physical support. The secondary cell walls are mainly composed of lignin, xylan and cellulose. Deficiency of overall stem development could cause weakened stems. Here we prove that WRKY13 acts in stem development. The wrky13 mutants take on a weaker stem phenotype. The number of sclerenchyma cells, stem diameter and the number of vascular bundles were reduced in wrky13 mutants. Lignin-synthesis-related genes were repressed in wrky13 mutants. Chromatin immunoprecipitation assays proved that WRKY13 could directly bind to the promoter of NST2. Taken together, we proposed that WRKY13 affected the overall development of stem. Identification of the role of WRKY13 may help to resolve agricultural problems caused by weaker stems. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
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Lodging (stem bending) is a serious problem causing severe yield reduction, poor grain filling, lower harvest index and deterioration in grain quality of chickpea in environments characterized by favorable temperatures and soil mo...
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Lodging (stem bending) is a serious problem causing severe yield reduction, poor grain filling, lower harvest index and deterioration in grain quality of chickpea in environments characterized by favorable temperatures and soil moisture conditions. Breeding for lodging resistance is also required to improving adaptation to better agronomy for achieving a breakthrough in its productivity and stability of production. However, no information is available on genetics of lodging resistance in chickpea. The objectives were to (i) characterize the newly identified lodging resistant germplasm FLIP07-183C for important plant characteristics and (ii) study the inheritance of lodging resistance in an inter-varietal cross between lodging susceptible high yielding desi cultivar Pusa 362 and the newly identified lodging resistant kabuli germplasm FLIP07-183C. FLIP07-183C was a tall, erect, late flowering genotype with semi-determinate stem growth habit and large seeds. It contained higher lignin content than the lodging susceptible cultivar, Pusa 362. Lodging resistance was found to be dominant over susceptibility. The segregation patterns in F-2 and F-3 of the cross Pusa 362 x FLIP07-183C showed that two dominant non-allelic genes with duplicate gene action controlled lodging resistance in FLIP07-183C. The two non-allelic duplicate dominant genes for lodging resistance in FLIP07-183C are designated as Sb1/sb1 and Sb2/sb2. The homozygous recessive for both alleles (sb1sb1sb2sb2) produced a lodging susceptible phenotype. The utilization of genes identified for lodging resistance has the major impact on chickpea breeding for better adaptation to cool climate, high fertility and irrigated environments.
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Lignin removal from lignocellulosic materials plays a great role in the utilization cellulose with high efficiency. In order to improve the quality of reconstituted tobacco sheet, lignin existed in tobacco stem was removed by enzy...
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Lignin removal from lignocellulosic materials plays a great role in the utilization cellulose with high efficiency. In order to improve the quality of reconstituted tobacco sheet, lignin existed in tobacco stem was removed by enzymatic hydrolysis with laccase enhanced by weak alkali treatment together with the addition of Tween 80 into laccase treatment system. It is found that lignin was partially removed by laccase. The treatment of tobacco stem with NaHCO3 resulted in the dissolution of lignin, and hence increased the porosity and specific surface area of the pretreated tobacco stem. Consequently, laccase could access to the tobacco stem more completely. The surface activity and dispersion of Tween 80 improved laccase activity, solubilization of degraded products of lignin, and contact interface between laccase and tobacco stem. The synergistic action of laccase, weak alkali and Tween 80 improved the ratio of lignin removal significantly, reaching as high as 40.3%.[GRAPHICS].
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The cinnamyl alcohol dehydrogenase (AtCAD) multigene family in Arabidopsis is composed of nine genes. Our previous studies focused on the two isoforms AtCAD C and AtCAD D which show a high homology to those related to lignificatio...
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The cinnamyl alcohol dehydrogenase (AtCAD) multigene family in Arabidopsis is composed of nine genes. Our previous studies focused on the two isoforms AtCAD C and AtCAD D which show a high homology to those related to lignification in other plants. This study focuses on the seven other Arabidopsis CAD for which functions are not yet elucidated. Their expression patterns were determined in different parts of Arabidopsis. Only CAD 1 protein can be detected in elongating stems, flowers, and siliques using Western-blot analysis. Tissue specific expression of CAD 1, B1, and G genes was determined using their promoters fused to the GUS reporter gene. CAD 1 expression was observed in primary xylem in accordance with a potential role in lignification. Arabidopsis T-DNA mutants knockout for the different genes CAD genes were characterized. Their stems displayed no substantial reduction of CAD activities for coniferyl and sinapyl alcohols as well as no modifications of lignin quantity and structure in mature inflorescence stems. Only a small reduction of lignin content could be observed in elongating stems of Atcad 1 mutant. These CAD genes in combination with the CAD D promoter were used to complement a CAD double mutant severely altered in lignification (cad c cad d). The expression of AtCAD A, B1, B2, F, and G had no effect on restoring a normal lignin profile of this mutant. In contrast, CAD 1 complemented partly this mutant as revealed by the partial restoration of conventional lignin units and by the decrease in the frequency of β-O-4 linked p-OH cinnamaldehydes.
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A factorial experiment, in the form of completely randomized design with two factors, was conducted in four replicates to investigate the effects of silica nanoparticles (nanoparticle-SiO2) and calcium chelate (Ca-chelate) on gerb...
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A factorial experiment, in the form of completely randomized design with two factors, was conducted in four replicates to investigate the effects of silica nanoparticles (nanoparticle-SiO2) and calcium chelate (Ca-chelate) on gerbera (Gerbera jamesonii L.). The first factor was nanoparticle-SiO2 concentration in nutrient solution (at four levels of 0, 20, 40 and 80 mg L-1) and the second factor was Ca-chelate concentration in nutrient solution (at four levels of 0, 60, 120 and 240 mg L-1). Number of leaves, number of flowers, number of flower buds and aborted flower buds, time of flowering, flower vase life, flower color, percentages of ash and lignin in stem, petal protein, as well as the amounts of silica and calcium in stem, leaf and root were measured. Compared to control, the treatment of 80 mg L-1 of nanoparticle-SiO2 with 60 mg L-1 of Ca-chelate increased the number of flowers by 182%. Moreover, applying 60 mg L-1 of Ca-chelate and 20 mg L-1 of nanoparticle-SiO2 led to flowers with 1.5 times higher longevity and 27% increase in flowering rate. The highest flower bud numbers and the lowest bud abortion were obtained in the treatment with 80 mg L-1 of nanoparticle-SiO2 and 60 mg L-1 of Ca-chelate. The highest concentration of calcium in stem, leaf and root as well as the highest amount of protein, pigment intensity and degree of transparency were observed in the treatment with 240 mg L-1 of Ca-chelate and 80 mg L-1 of nanoparticle-SiO2.
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Lignin is a complex aromatic heteropolymer that plays essential roles in mechanical support, water transport, and response to biotic and abiotic stresses. The tea plant is a leaf-type beverage crop, which serves as a resource for ...
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Lignin is a complex aromatic heteropolymer that plays essential roles in mechanical support, water transport, and response to biotic and abiotic stresses. The tea plant is a leaf-type beverage crop, which serves as a resource for non-alcoholic beverage tea. The content and distribution of lignin in tea plant leaves seriously affect the quality of tea. However, the biosynthetic pathways of lignin remain to be characterized in the tea plant. In the present study, lignin accumulation was investigated in tea plant leaves and stems at three developmental stages. The lignin content continuously increased during leaf and stem development in both tea plant cultivars Fudingdabai' and Suchazao.' The lignin distribution and anatomical characteristics of the tea plant leaves coincided with lignin accumulation and showed that lignin is mainly distributed in the epidermis, xylem, and vascular bundle sheath. Suchazao' exhibits a low lignin content and lacks a vascular bundle sheath. Twelve genes encoding the enzymes involved in the lignin biosynthesis of tea plant were identified and included CsPAL, CsC4H, Cs4CL, CsHCT, CsC3H, CsCCoAOMT, CsCCR, CsCAD, CsF5H, CsCOMT, CsPER, and CsLAC. The expression profiling of lignin biosynthesis-related genes and analysis of lignin accumulation may help elaborate the regulatory mechanisms of lignin biosynthesis in tea plant.
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The aim of this paper is to elucidate relationship between anatomical changes and lignin deposition dynamics in the cell wall of barley (Hordeum vulgare L.) internodes during four growth stages: heading, flowering, grain filling a...
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The aim of this paper is to elucidate relationship between anatomical changes and lignin deposition dynamics in the cell wall of barley (Hordeum vulgare L.) internodes during four growth stages: heading, flowering, grain filling and ripening. Microscopy was used to analyze anatomical changes related to lignin deposition whereas peroxidase activity was spectrophotometrically determined. In transversal sections lignin was found to be predominant in the sclerenchyma ring in cortex, where particularly lignified cell walls were found. Peroxidase activity was increased in older internodes and their localization in situ was in positive correlation with tissue lignification. Our results showed that, depending on the cultivar, at the flowering and grain filling stages intensive lignin synthesis and deposition occurred. This showed that deposition of lignin in the cell wall at a particular growth stage is in correlation with the lodging resistant phenotype of the investigated cultivars. The results contribute to the understanding of the lignin deposition process during barley development and consequential cell wall thickness.
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