scholarly journals LACCASE14 is required for the deposition of guaiacyl lignin and affects cell wall digestibility in poplar

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Shifei Qin ◽  
Chunfen Fan ◽  
Xiaohong Li ◽  
Yi Li ◽  
Jian Hu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Genetic Manipulation ◽  
Lignin Content ◽  
Biomass Conversion ◽  
Enzymatic Saccharification ◽  
Lignin Biosynthesis ◽  
Populus Tomentosa ◽  
Wall Structure ◽  
Biomass Saccharification

Abstract Background The recalcitrance of lignocellulosic biomass provided technical and economic challenges in the current biomass conversion processes. Lignin is considered as a crucial recalcitrance component in biomass utilization. An in-depth understanding of lignin biosynthesis can provide clues to overcoming the recalcitrance. Laccases are believed to play a role in the oxidation of lignin monomers, leading to the formation of higher-order lignin. In plants, functions of only a few laccases have been evaluated, so little is known about the effect of laccases on cell wall structure and biomass saccharification. Results In this study, we screened a gain-of-function mutant with a significant increase in lignin content from Arabidopsis mutant lines overexpressing a full-length poplar cDNA library. Further analysis confirmed that a Chinese white poplar (Populus tomentosa) laccase gene PtoLAC14 was inserted into the mutant, and PtoLAC14 could functionally complement the Arabidopsis lac4 mutant. Overexpression of PtoLAC14 promoted the lignification of poplar and reduced the proportion of syringyl/guaiacyl. In contrast, the CRISPR/Cas9-generated mutation of PtLAC14 results in increased the syringyl/guaiacyl ratios, which led to integrated enhancement on biomass enzymatic saccharification. Notably, the recombinant PtoLAC14 protein showed higher oxidized efficiency to coniferyl alcohol (precursor of guaiacyl unit) in vitro. Conclusions This study shows that PtoLAC14 plays an important role in the oxidation of guaiacyl deposition on cell wall. The reduced recalcitrance of the PtoLAC14-KO lines suggests that PtoLAC14 is an elite target for cell wall engineering, and genetic manipulation of this gene will facilitate the utilization of lignocellulose.

scholarly journals Identifying transcription factors that reduce wood recalcitrance and improve enzymatic degradation of xylem cell wall in Populus

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chiaki Hori ◽  
Naoki Takata ◽  
Pui Ying Lam ◽  
Yuki Tobimatsu ◽  
Soichiro Nagano ◽  
...  
Keyword(s):  
Cell Wall ◽  
Populus Tremuloides ◽  
Cell Walls ◽  
Enzymatic Degradation ◽  
Plant Biomass ◽  
Lignin Content ◽  
Enzymatic Saccharification ◽  
Wall Structure ◽  
Xylem Cell

AbstractDeveloping an efficient deconstruction step of woody biomass for biorefinery has been drawing considerable attention since its xylem cell walls display highly recalcitrance nature. Here, we explored transcriptional factors (TFs) that reduce wood recalcitrance and improve saccharification efficiency in Populus species. First, 33 TF genes up-regulated during poplar wood formation were selected as potential regulators of xylem cell wall structure. The transgenic hybrid aspens (Populus tremula × Populus tremuloides) overexpressing each selected TF gene were screened for in vitro enzymatic saccharification. Of these, four transgenic seedlings overexpressing previously uncharacterized TF genes increased total glucan hydrolysis on average compared to control. The best performing lines overexpressing Pt × tERF123 and Pt × tZHD14 were further grown to form mature xylem in the greenhouse. Notably, the xylem cell walls exhibited significantly increased total xylan hydrolysis as well as initial hydrolysis rates of glucan. The increased saccharification of Pt × tERF123-overexpressing lines could reflect the improved balance of cell wall components, i.e., high cellulose and low xylan and lignin content, which could be caused by upregulation of cellulose synthase genes upon the expression of Pt × tERF123. Overall, we successfully identified Pt × tERF123 and Pt × tZHD14 as effective targets for reducing cell wall recalcitrance and improving the enzymatic degradation of woody plant biomass.

scholarly journals The in vivo impact of MsLAC1, a Miscanthus laccase isoform, on lignification and lignin composition contrasts with its in vitro substrate preference

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Feng He ◽  
Katja Machemer-Noonan ◽  
Philippe Golfier ◽  
Faride Unda ◽  
Johanna Dechert ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factors ◽  
Lignin Content ◽  
Lignin Biosynthesis ◽  
Lignin Composition ◽  
Xylem Fibers ◽  
Breeding Target

Abstract Background Understanding lignin biosynthesis and composition is of central importance for sustainable bioenergy and biomaterials production. Species of the genus Miscanthus have emerged as promising bioenergy crop due to their rapid growth and modest nutrient requirements. However, lignin polymerization in Miscanthus is poorly understood. It was previously shown that plant laccases are phenol oxidases that have multiple functions in plant, one of which is the polymerization of monolignols. Herein, we link a newly discovered Miscanthus laccase, MsLAC1, to cell wall lignification. Characterization of recombinant MsLAC1 and Arabidopsis transgenic plants expressing MsLAC1 were carried out to understand the function of MsLAC1 both in vitro and in vivo. Results Using a comprehensive suite of molecular, biochemical and histochemical analyses, we show that MsLAC1 localizes to cell walls and identify Miscanthus transcription factors capable of regulating MsLAC1 expression. In addition, MsLAC1 complements the Arabidopsis lac4–2 lac17 mutant and recombinant MsLAC1 is able to oxidize monolignol in vitro. Transgenic Arabidopsis plants over-expressing MsLAC1 show higher G-lignin content, although recombinant MsLAC1 seemed to prefer sinapyl alcohol as substrate. Conclusions In summary, our results suggest that MsLAC1 is regulated by secondary cell wall MYB transcription factors and is involved in lignification of xylem fibers. This report identifies MsLAC1 as a promising breeding target in Miscanthus for biofuel and biomaterial applications.

scholarly journals Effect of Exogenously Applied 24-Epibrassinolide and Brassinazole on Xylogenesis and Microdistribution of Cell Wall Polymers in Leucaena leucocephala (Lam) De Wit

2021 ◽  
Author(s):  
S. Pramod ◽  
M. Anju ◽  
H. Rajesh ◽  
A. Thulaseedharan ◽  
Karumanchi S. Rao
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Leucaena Leucocephala ◽  
Higher Plants ◽  
Lignin Content ◽  
Wood Quality ◽  
Wall Structure ◽  
Vessel Element ◽  
Xylem Differentiation ◽  
Cell Wall Polymers

AbstractPlant growth regulators play a key role in cell wall structure and chemistry of woody plants. Understanding of these regulatory signals is important in advanced research on wood quality improvement in trees. The present study is aimed to investigate the influence of exogenous application of 24-epibrassinolide (EBR) and brassinosteroid inhibitor, brassinazole (BRZ) on wood formation and spatial distribution of cell wall polymers in the xylem tissue of Leucaena leucocephala using light and immuno electron microscopy methods. Brassinazole caused a decrease in cambial activity, xylem differentiation, length and width of fibres, vessel element width and radial extent of xylem suggesting brassinosteroid inhibition has a concomitant impact on cell elongation, expansion and secondary wall deposition. Histochemical studies of 24-epibrassinolide treated plants showed an increase in syringyl lignin content in the xylem cell walls. Fluorescence microscopy and transmission electron microscopy studies revealed the inhomogenous pattern of lignin distribution in the cell corners and middle lamellae region of BRZ treated plants. Immunolocalization studies using LM10 and LM 11 antibodies have shown a drastic change in the micro-distribution pattern of less substituted and highly substituted xylans in the xylem fibres of plants treated with EBR and BRZ. In conclusion, present study demonstrates an important role of brassinosteroid in plant development through regulating xylogenesis and cell wall chemistry in higher plants.

scholarly journals Targeting hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase for lignin modification in Brachypodium distachyon

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Juan Carlos Serrani-Yarce ◽  
Luis Escamilla-Trevino ◽  
Jaime Barros ◽  
Lina Gallego-Giraldo ◽  
Yunqiao Pu ◽  
...  
Keyword(s):  
Negative Impact ◽  
Lignin Content ◽  
Brachypodium Distachyon ◽  
Lignin Biosynthesis ◽  
Reverse Direction ◽  
Wall Structure ◽  
Kinetic Properties ◽  
Loss Of Function ◽  
Down Regulation ◽  
Lignin Modification

Abstract Background Hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) is a central enzyme of the so-called “esters” pathway to monolignols. As originally envisioned, HCT functions twice in this pathway, to form coumaroyl shikimate and then, in the “reverse” direction, to convert caffeoyl shikimate to caffeoyl CoA. The discovery of a caffeoyl shikimate esterase (CSE) that forms caffeic acid directly from caffeoyl shikimate calls into question the need for the reverse HCT reaction in lignin biosynthesis. Loss of function of HCT gives severe growth phenotypes in several dicot plants, but less so in some monocots, questioning whether this enzyme, and therefore the shikimate shunt, plays the same role in both monocots and dicots. The model grass Brachypodium distachyon has two HCT genes, but lacks a classical CSE gene. This study was therefore conducted to evaluate the utility of HCT as a target for lignin modification in a species with an “incomplete” shikimate shunt. Results The kinetic properties of recombinant B. distachyon HCTs were compared with those from Arabidopsis thaliana, Medicago truncatula, and Panicum virgatum (switchgrass) for both the forward and reverse reactions. Along with two M. truncatula HCTs, B. distachyon HCT2 had the least kinetically unfavorable reverse HCT reaction, and this enzyme is induced when HCT1 is down-regulated. Down regulation of B. distachyon HCT1, or co-down-regulation of HCT1 and HCT2, by RNA interference led to reduced lignin levels, with only modest changes in lignin composition and molecular weight. Conclusions Down-regulation of HCT1, or co-down-regulation of both HCT genes, in B. distachyon results in less extensive changes in lignin content/composition and cell wall structure than observed following HCT down-regulation in dicots, with little negative impact on biomass yield. Nevertheless, HCT down-regulation leads to significant improvements in biomass saccharification efficiency, making this gene a preferred target for biotechnological improvement of grasses for bioprocessing.

scholarly journals Distinct and overlapping functions of Miscanthus sinensis MYB transcription factors SCM1 and MYB103 in lignin biosynthesis

2019 ◽  
Author(s):  
Philippe Golfier ◽  
Faride Unda ◽  
Emily K. Murphy ◽  
Jianbo Xie ◽  
Feng He ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcriptional Regulation ◽  
Secondary Cell Wall ◽  
Lignin Content ◽  
Lignin Biosynthesis ◽  
Miscanthus Sinensis ◽  
Cell Wall Formation ◽  
Transcriptional Responses ◽  
Secondary Cell Wall Formation ◽  
Wall Formation

AbstractCell wall recalcitrance is a major constraint for the exploitation of lignocellulosic biomass as renewable resource for energy and bio-based products. Transcriptional regulators of the lignin biosynthetic pathway represent promising targets for tailoring lignin content and composition in plant secondary cell walls. A wealth of research in model organisms has revealed that transcriptional regulation of secondary cell wall formation is orchestrated by a hierarchical transcription factor (TF) network with NAC TFs as master regulators and MYB factors in the lower tier regulators. However, knowledge about the transcriptional regulation of lignin biosynthesis in lignocellulosic feedstocks, such as Miscanthus, is limited. Here, we characterized two Miscanthus MYB TFs, MsSCM1 and MsMYB103, and compared their transcriptional impact with that of the master regulator MsSND1. In Miscanthus leaves MsSCM1 and MsMYB103 are expressed at growth stages associated with lignification. Ectopic expression of MsSCM1 and MsMYB103 in tobacco leaves was sufficient to trigger secondary cell wall deposition with distinct sugar and lignin composition. Moreover, RNA-seq analysis revealed that the transcriptional responses to MsSCM1 and MsMYB103 overexpression showed extensive overlap with the response to MsSND1, but were distinct from each other, underscoring the inherent complexity of secondary cell wall formation. Together, MsSCM1 and MsMYB103 represent interesting targets for manipulations of lignin content and composition in Miscanthus towards tailored biomass.

Prediction of forage digestibility from some laboratory procedures. 2. Comparison of in vivo digestibility at two institutes.

1971 ◽  
Vol 19 (2) ◽  
pp. 106-113
Author(s):  
B. Deinum
Keyword(s):  
Cell Wall ◽  
Organic Matter ◽  
Sulfuric Acid ◽  
Lignin Content ◽  
Forage Digestibility ◽  
Significant Difference ◽  
Laboratory Procedures ◽  
Sulfuric Acid Lignin

For part 1 see Abst. 1564, Vol. 40. 2. The relation between digestibilities of organic matter in vivo and in vitro did not differ significantly between the institutes at Hoorn and Wageningen. No difference was found in digestibility of the cell wall constituents in relation to the lignin content, nor was there a significant difference in the relation between the percentage of digestible cell contents and the percentage of cell contents in forage from well managed pastures. Twelve forages of highly digestible perennial ryegrass deviated from these farm forages at Wageningen, showing smaller excretion of bacterial and endogenous residue. Comparison of the 2 lignin procedures showed that 72% sulfuric acid lignin gave consistent residual standard deviations of digestibility of cell wall constituents; permanganate lignin gave smaller errors in forages at Wageningen but greater errors in forages at Hoorn. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Cell wall alterations in staphylococci growing in situ in experimental osteomyelitis

1987 ◽  
Vol 33 (2) ◽  
pp. 142-150 ◽  
Author(s):  
J. W. Costerton ◽  
D. W. Lambe Jr. ◽  
K.-J. Mayberry-Carson ◽  
B. Tober-Meyer
Keyword(s):  
Cell Wall ◽  
Cell Size ◽  
Wall Structure ◽  
Specific Cell ◽  
Experimental Osteomyelitis ◽  
Rich Media ◽  
Rabbit Tibia ◽  
Rabbit Bone

When cells of both Staphylococcus aureus and Staphylococcus epidermidis are grown in batch culture in nutrient-rich media, their cell walls are regular in thickness, their cell size is within the normal range for each species, and their septation patterns are orderly. When cells of each of these species are examined directly in infected tissue in the rabbit tibia model infection, their cell wall thickness is often much increased and very irregular around the circumference of the cell, their cell size is often increased, and their septation patterns are often severely deranged. All of these alterations in cell wall structure occur in the absence of antibiotics, and we suggest that they may be an expression of phenotypic plasticity in response to altered environmental conditions such as specific nutrient limitations, the presence of antibacterial factors, and growth of the cells on hard surfaces such as rabbit bone or plastic catheters. Some of these specific cell wall alterations are also seen when staphylococcal cells are exposed, in vitro or in vivo, to antibiotics such as clindamycin, but we emphasize that growth in tissue alone is sufficient for their induction.

Molecular xylem cell wall structure of an inclined Cycas micronesica stem, a tropical gymnosperm

IAWA Journal ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Clemens M. Altaner ◽  
Michael C. Jarvis ◽  
Jack B. Fisher ◽  
Thomas E. Marler
Keyword(s):  
Cell Wall ◽  
Compression Wood ◽  
Lignin Content ◽  
Microfibril Angle ◽  
Picea Sitchensis ◽  
Wall Structure ◽  
Crystalline Cellulose ◽  
Cellulose Structure ◽  
Molecular Features ◽  
Cellulose Fibrils

The molecular structure of tracheid walls of an inclined eccentrically grown stem of Cycas micronesica K.D. Hill did not differ between the upper and lower side. The absence the typical molecular features of compression wood tracheids, i.e. an increased galactose and lignin content as well as an increased microfibril angle, indicated that cycads do not have the ability to form even very mild forms of compression wood, which lacks anatomical features commonly observed in compression wood. Analysis of the sugar monomers in Cycas micronesica tracheids did reveal a rather unique composition of the non-cellulosic polysaccharides for a gymnosperm. The low mannose and high xylose content resembled a cell wall matrix common in angiosperms. The crystalline cellulose structure in Cycas micronesica tracheids closely resembled those of secondary cell walls in Picea sitchensis (Bong.) Carr. tracheids. However, the spacing between the sheets of cellulose chains was wider and the cellulose fibrils appeared to form larger aggregates than in Sitka spruce tracheids.

scholarly journals Characterization and functional analysis of the Hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase (HCT) gene family in poplar

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10741
Author(s):  
Nan Chao ◽  
Qi Qi ◽  
Shuang Li ◽  
Brent Ruan ◽  
Xiangning Jiang ◽  
...  
Keyword(s):  
Shikimic Acid ◽  
Lignin Content ◽  
Expression Profiles ◽  
Populus Trichocarpa ◽  
Functional Divergence ◽  
Lignin Biosynthesis ◽  
Populus Tomentosa ◽  
Motif Analysis ◽  
Monolignol Biosynthesis ◽  
Populus Tomentosa Carr

Hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase (HCT) divides the mass flux to H, G and S units in monolignol biosynthesis and affects lignin content. Ten HCT homologs were identified in the Populus trichocarpa (Torr. & Gray) genome. Both genome duplication and tandem duplication resulted in the expansion of HCT orthologs in Populus. Comprehensive analysis including motif analysis, phylogenetic analysis, expression profiles and co-expression analysis revealed the divergence and putative function of these candidate PoptrHCTs. PoptrHCT1 and 2 were identified as likely involved in lignin biosynthesis. PoptrHCT9 and 10- are likely to be involved in plant development and the response to cold stress. Similar functional divergence was also identified in Populus tomentosa Carr. Enzymatic assay of PtoHCT1 showed that PtoHCT1 was able to synthesize caffeoyl shikimate using caffeoyl-CoA and shikimic acid as substrates.

scholarly journals Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction

2021 ◽  
Vol 17 (3) ◽  
pp. e1009468
Author(s):  
Joshua A. F. Sutton ◽  
Oliver T. Carnell ◽  
Lucia Lafage ◽  
Joe Gray ◽  
Jacob Biboy ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cell Walls ◽  
Ex Vivo ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Bacterial Cells ◽  
Human Macrophages ◽  
Structure And Dynamics

Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which correlated with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease.

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