Reduction of Lignin Content by Suppression of Expression of the LIM Domain Transcription Factor in Eucalyptus camaldulensis

Abstract We report a reduction of lignin content in the woody plant Eucalyptus camaldulensis by the suppression of gene expression of the LIM domain transcription factor. Previously, we identified a cDNA encoding the tobacco (Nicotiana tabacum) LIM domain transcription factor, Nt1iml, involved in lignin biosynthesis and that specifically binds to an important cis-acting element, the PALbox sequence. The orthologous Eucalyptus gene of Ntliml, namely Ecliml, was isolated from the E. camaldulensis cDNA library (84% amino acid identity). The antisense Ntliml construct with a kanamycin-resistant gene was introduced into E. camaldulensis. The transgenic Eucalyptus plants grown in the greenhouse showed decreased expression levels of severallignin biosynthesis genes, phenylalanine ammonialyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-hydroxycinnamate CoA ligase (4CL). The abnormal phenotypic changes and a 29% reduction of lignin content were observed in the line LG12, in which the transcript level of Ecliml was most1y suppressed. Ec1iml is one of the key transcription factors involved in lignin biosynthesis.

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The BpMYB4 Transcription Factor From Betula platyphylla Contributes Toward Abiotic Stress Resistance and Secondary Cell Wall Biosynthesis

Frontiers in Plant Science ◽

10.3389/fpls.2020.606062 ◽

2021 ◽

Vol 11 ◽

Author(s):

Ying Yu ◽

Huizi Liu ◽

Nan Zhang ◽

Caiqiu Gao ◽

Liwang Qi ◽

...

Keyword(s):

Cell Wall ◽

Transcription Factor ◽

Abiotic Stress ◽

Transgenic Plants ◽

Stress Resistance ◽

Secondary Cell Wall ◽

Lignin Content ◽

Lignin Biosynthesis ◽

Betula Platyphylla ◽

Wild Type

The MYB (v-myb avian myeloblastosis viral oncogene homolog) family is one of the largest transcription factor families in plants, and is widely involved in the regulation of plant metabolism. In this study, we show that a MYB4 transcription factor, BpMYB4, identified from birch (Betula platyphylla Suk.) and homologous to EgMYB1 from Eucalyptus robusta Smith and ZmMYB31 from Zea mays L. is involved in secondary cell wall synthesis. The expression level of BpMYB4 was higher in flowers relative to other tissues, and was induced by artificial bending and gravitational stimuli in developing xylem tissues. The expression of this gene was not enriched in the developing xylem during the active season, and showed higher transcript levels in xylem tissues around sprouting and near the dormant period. BpMYB4 also was induced express by abiotic stress. Functional analysis indicated that expression of BpMYB4 in transgenic Arabidopsis (Arabidopsis thaliana) plants could promote the growth of stems, and result in increased number of inflorescence stems and shoots. Anatomical observation of stem sections showed lower lignin deposition, and a chemical contents test also demonstrated increased cellulose and decreased lignin content in the transgenic plants. In addition, treatment with 100 mM NaCl and 200 mM mannitol resulted in the germination rate of the over-expressed lines being higher than that of the wild-type seeds. The proline content in transgenic plants was higher than that in WT, but MDA content was lower than that in WT. Further investigation in birch using transient transformation techniques indicated that overexpression of BpMYB4 could scavenge hydrogen peroxide and O2.– and reduce cell damage, compared with the wild-type plants. Therefore, we believe that BpMYB4 promotes stem development and cellulose biosynthesis as an inhibitor of lignin biosynthesis, and has a function in abiotic stress resistance.

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Transcript abundances of LIM transcription factor, 4CL, CAld5H and CesAs affect wood properties in Eucalyptus globulus

Silvae Genetica ◽

10.1515/sg-2011-0038 ◽

2011 ◽

Vol 60 (1-6) ◽

pp. 288-296 ◽

Cited By ~ 5

Author(s):

N. Negishi ◽

K. Nanto ◽

K. Hayashi ◽

S. Onogi ◽

A. Kawaoka

Keyword(s):

Transcription Factor ◽

Eucalyptus Globulus ◽

Woody Plant ◽

Wood Quality ◽

Wood Properties ◽

Gene Transcript ◽

Lim Domain ◽

Positive Correlation ◽

Hardwood Species ◽

Coa Ligase

AbstractEucalyptus globulusis the main hardwood species grown in pulpwood plantations in temperate regions of the world. We have cloned six genes influencing wood quality including the LIM domain transcription factor (LIM), 4-coumarate-CoA ligase (4CL), coniferaldehyde 5-hydroxylase (CAld5H) and the three catalytic units of cellulose synthase (CesA), fromE. globulus. The transcript abundances of LIM in basal stems of ten independentE. globuluslines showed similar patterns to those of 4CL. We investigated the correlation between gene transcript abundances and wood qualities such as Klason lignin (KL) content, syringaldehyde/vanillin (S/V) ratio and holocellulose (HC) content. Expression of the LIM and 4CL were positively correlated with KL content. A highly significant positive correlation was observed between CAld5H expression and S/V ratio. Furthermore, a ratio of the sum of the transcript abundances of three CesA1, CesA2 and CesA3 to 4CL showed a positive correlation with a ratio of HC/KL content that positively correlated with the chemically extracted fiber content in this woody plant.

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A Novel NAC Transcription Factor From Eucalyptus, EgNAC141, Positively Regulates Lignin Biosynthesis and Increases Lignin Deposition

Frontiers in Plant Science ◽

10.3389/fpls.2021.642090 ◽

2021 ◽

Vol 12 ◽

Author(s):

YiMing Sun ◽

Chunxue Jiang ◽

Ruiqi Jiang ◽

Fengying Wang ◽

Zhenguo Zhang ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Lignin Content ◽

Eucalyptus Grandis ◽

Lignin Biosynthesis ◽

Wood Formation ◽

Nac Transcription Factor ◽

Luciferase Assay ◽

Large Set ◽

Biosynthetic Genes

Wood formation is a complicated process under the control of a large set of transcription factors. NAC transcription factors are considered “master switches” in this process. However, few NAC members have been cloned and characterized in Eucalyptus, which is one of the most economically important woody plants. Here, we reported an NAC transcription factor from Eucalyptus grandis, EgNAC141, which has no Arabidopsis orthologs associated with xylogenesis-related processes. EgNAC141 was predominantly expressed in lignin-rich tissues, such as the stem and xylem. Overexpression of EgNAC141 in Arabidopsis resulted in stronger lignification, larger xylem, and higher lignin content. The expression of lignin biosynthetic genes in transgenic plants was significantly higher compared with wild-type plants. The transient expression of EgNAC141 activated the expression of Arabidopsis lignin biosynthetic genes in a dual-luciferase assay. Overall, these results showed that EgNAC141 is a positive regulator of lignin biosynthesis and may help us understand the regulatory mechanism of wood formation.

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

Biotechnology for Biofuels ◽

10.1186/s13068-021-01905-1 ◽

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.

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Overexpressing the HD-Zip class II transcription factor EcHB1 from Eucalyptus camaldulensis increased the leaf photosynthesis and drought tolerance of Eucalyptus

Scientific Reports ◽

10.1038/s41598-019-50610-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Keisuke Sasaki ◽

Yuuki Ida ◽

Sakihito Kitajima ◽

Tetsu Kawazu ◽

Takashi Hibino ◽

...

Keyword(s):

Transcription Factor ◽

Leaf Area ◽

Leucine Zipper ◽

Eucalyptus Grandis ◽

Eucalyptus Camaldulensis ◽

Class Ii ◽

Cell Multiplication ◽

Leaf Photosynthesis ◽

Unit Leaf

Abstract Alteration in the leaf mesophyll anatomy by genetic modification is potentially a promising tool for improving the physiological functions of trees by improving leaf photosynthesis. Homeodomain leucine zipper (HD-Zip) transcription factors are candidates for anatomical alterations of leaves through modification of cell multiplication, differentiation, and expansion. Full-length cDNA encoding a Eucalyptus camaldulensis HD-Zip class II transcription factor (EcHB1) was over-expressed in vivo in the hybrid Eucalyptus GUT5 generated from Eucalyptus grandis and Eucalyptus urophylla. Overexpression of EcHB1 induced significant modification in the mesophyll anatomy of Eucalyptus with enhancements in the number of cells and chloroplasts on a leaf-area basis. The leaf-area-based photosynthesis of Eucalyptus was improved in the EcHB1-overexpression lines, which was due to both enhanced CO2 diffusion into chloroplasts and increased photosynthetic biochemical functions through increased number of chloroplasts per unit leaf area. Additionally, overexpression of EcHB1 suppressed defoliation and thus improved the growth of Eucalyptus trees under drought stress, which was a result of reduced water loss from trees due to the reduction in leaf area with no changes in stomatal morphology. These results gave us new insights into the role of the HD-Zip II gene.

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TheEucalyptuslinker histone variant EgH1.3 cooperates with the transcription factor EgMYB1 to control lignin biosynthesis during wood formation

New Phytologist ◽

10.1111/nph.14129 ◽

2016 ◽

Vol 213 (1) ◽

pp. 287-299 ◽

Cited By ~ 24

Author(s):

Marçal Soler ◽

Anna Plasencia ◽

Romain Larbat ◽

Cécile Pouzet ◽

Alain Jauneau ◽

...

Keyword(s):

Transcription Factor ◽

Lignin Biosynthesis ◽

Wood Formation ◽

Histone Variant

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Autoregulated Expression of Schizosaccharomyces pombe Meiosis-Specific Transcription Factor Mei4 and a Genome-Wide Search for Its Target Genes

Genetics ◽

10.1093/genetics/154.4.1497 ◽

2000 ◽

Vol 154 (4) ◽

pp. 1497-1508 ◽

Cited By ~ 4

Author(s):

Hiroko Abe ◽

Chikashi Shimoda

Keyword(s):

Transcription Factor ◽

Schizosaccharomyces Pombe ◽

Target Genes ◽

Northern Blotting ◽

Forkhead Transcription Factor ◽

Gene Encoding ◽

Putative Promoter Region ◽

Cis Acting ◽

A Genome ◽

Genome Wide Search

Abstract The Schizosaccharomyces pombe mei4+ gene encoding a forkhead transcription factor is necessary for the progression of meiosis and sporulation. We searched for novel meiotic genes, the expression of which is dependent on Mei4p, since only the spo6+ gene has been assigned to its targets. Six known genes responsible for meiotic recombination were examined by Northern blotting, but none were Mei4 dependent for transcription. We determined the important cis-acting element, designated FLEX, to which Mei4p can bind. The S. pombe genome sequence database (The Sanger Centre, UK) was scanned for the central core heptamer and its flanking 3′ sequence of FLEX composed of 17 nucleotides, and 10 candidate targets of Mei4 were selected. These contained a FLEX-like sequence in the 5′ upstream nontranslatable region within 1 kb of the initiation codon. Northern blotting confirmed that 9 of them, named mde1+ to mde9+, were transcriptionally induced during meiosis and were dependent on mei4+. Most mde genes have not been genetically defined yet, except for mde9+, which is identical to spn5+, which encodes one of the septin family of proteins. mde3+ and a related gene pit1+ encode proteins related to Saccharomyces cerevisiae Ime2. The double disruptant frequently produced asci having an abnormal number and size of spores, although it completed meiosis. We also found that the forkhead DNA-binding domain of Mei4p binds to the FLEX-like element in the putative promoter region of mei4 and that the maximum induction level of mei4 mRNA required functional mei4 activity. Furthermore, expression of a reporter gene driven by the authentic mei4 promoter was induced in vegetative cells by ectopic overproduction of Mei4p. These results suggest that mei4 transcription is positively autoregulated.

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How affinity of the ELT-2 GATA factor binding to cis-acting regulatory sites controls Caenorhabditis elegans intestinal gene transcription

Development ◽

10.1242/dev.190330 ◽

2020 ◽

Vol 147 (14) ◽

pp. dev190330

Author(s):

Brett R. Lancaster ◽

James D. McGhee

Keyword(s):

Transcription Factor ◽

Caenorhabditis Elegans ◽

Binding Affinity ◽

Experimental System ◽

Quantitative Relationship ◽

Gata Factor ◽

Unknown Parameters ◽

Cis Acting ◽

Complicated Model

ABSTRACTWe define a quantitative relationship between the affinity with which the intestine-specific GATA factor ELT-2 binds to cis-acting regulatory motifs and the resulting transcription of asp-1, a target gene representative of genes involved in Caenorhabditis elegans intestine differentiation. By establishing an experimental system that allows unknown parameters (e.g. the influence of chromatin) to effectively cancel out, we show that levels of asp-1 transcripts increase monotonically with increasing binding affinity of ELT-2 to variant promoter TGATAA sites. The shape of the response curve reveals that the product of the unbound ELT-2 concentration in vivo [i.e. (ELT-2free) or ELT-2 ‘activity’] and the largest ELT-XXTGATAAXX association constant (Kmax) lies between five and ten. We suggest that this (unitless) product [Kmax×(ELT-2free) or the equivalent product for any other transcription factor] provides an important quantitative descriptor of transcription-factor/regulatory-motif interaction in development, evolution and genetic disease. A more complicated model than simple binding affinity is necessary to explain the fact that ELT-2 appears to discriminate in vivo against equal-affinity binding sites that contain AGATAA instead of TGATAA.

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

10.1101/629709 ◽

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.

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Gains achieved by molecular approaches in the area of lignification

Pure and Applied Chemistry ◽

10.1351/pac200173030561 ◽

2001 ◽

Vol 73 (3) ◽

pp. 561-566 ◽

Cited By ~ 5

Author(s):

Alain-M. Boudet ◽

Matthieu Chabannes

Keyword(s):

Molecular Biology ◽

Lignin Content ◽

Ectopic Expression ◽

Lignin Biosynthesis ◽

Cell Types ◽

Molecular Approaches ◽

Regulatory Circuits ◽

Recent Developments ◽

Spatio Temporal ◽

Different Cell Types

In this article we highlight the contribution of molecular biology and lignin genetic engineering toward a better understanding of lignin biosynthesis and spatio-temporal deposition of lignin. Specific examples from the literature and from our laboratory will serve to underline the chemical flexibility of lignins, the complexity of the regulatory circuits involved in their synthesis, and the specific behavior of different cell types within the xylem. We will also focus on strategies aiming to reduce the lignin content or to modify the lignin composition of plants and present their impact on plant development. We will show that the ectopic expression of a specific transgene may have a different impact, depending on the genetic background, and that plants with a severe reduction in lignin content may undergo normal development. Lignification is currently benefiting enormously from recent developments in molecular biology and transgenesis, and the progress made opens the way for future developments to study how the walls of lignified plant cells are built and organized.

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