Wout Boerjan - Academia.edu (original) (raw)

Papers by Wout Boerjan

Research paper thumbnail of Reassessing the claimed cytokinin-substituting activity of dehydrodiconiferyl alcohol glucoside

Proceedings of the National Academy of Sciences

Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with rep... more Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with reported cytokinin-substituting and cell-division-promoting activity. Despite its claimed activity, DCG did not trigger morphological changes in Arabidopsis seedlings nor did it alter transcriptional shifts in cell division and cytokinin-responsive genes. In reinvestigating the bioactivity of DCG in its original setting, the previously described stimulation of tobacco callus formation could not be confirmed. No evidence was found that DCG is actually taken up by plant cells, which could explain the absence of any observable activity in the performed experiments. The DCG content in plant tissue increased when feeding explants with the DCG aglycone dehydrodiconiferyl alcohol, which is readily taken up and converted to DCG by plant cells. Despite the increased DCG content, no activity for this metabolite could be demonstrated. Our results therefore demand a reevaluation of the often-quoted cyt...

Research paper thumbnail of Downregulation of barley ferulate 5-hydroxylase dramatically alters straw lignin structure without impact on mechanical properties

Frontiers in Plant Science

Barley is a major cereal crop for temperate climates, and a diploid genetic model for polyploid w... more Barley is a major cereal crop for temperate climates, and a diploid genetic model for polyploid wheat. Cereal straw biomass is an attractive source of feedstock for green technologies but lignin, a key determinant of feedstock recalcitrance, complicates bio-conversion processes. However, manipulating lignin content to improve the conversion process could negatively affect agronomic traits. An alternative approach is to manipulate lignin composition which influences the physical and chemical properties of straw. This study validates the function of a barley ferulate 5-hydroxylase gene and demonstrates that its downregulation using the RNA-interference approach substantially impacts lignin composition. We identified five barley genes having putative ferulate 5-hydroxylase activity. Downregulation of HvF5H1 substantially reduced the lignin syringyl/guaiacyl (S/G) ratio in straw while the lignin content, straw mechanical properties, plant growth habit, and grain characteristics all rema...

Research paper thumbnail of Incorporation of catechyl monomers into lignins: lignification from the non-phenolic end via Diels–Alder cycloaddition?

Green Chemistry, 2021

Catechyl monomers 1-electron-oxidize and undergo radical coupling to produce benzodioxane units i... more Catechyl monomers 1-electron-oxidize and undergo radical coupling to produce benzodioxane units in lignin. Derived o-quinones undergo Diels–Alder reactions giving oxatricyclo and new benzodioxane products, but does this occur in lignification?.

Research paper thumbnail of Field and saccharification performances of poplars severely downregulated in <i>CAD1</i>

New Phytologist, Aug 9, 2022

 Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hy... more  Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hydrolysis. Greenhouse-grown poplars severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE 1 (CAD1), the enzyme catalyzing the last step in the monolignol-specific branch of lignin biosynthesis, have increased saccharification yields and normal growth.  Here, we assess the performance of these hpCAD poplars in the field under short rotation coppice culture for two consecutive rotations of one and three years.  While one-year-old hpCAD wood had 10% less lignin, three-year-old hpCAD wood had wild-type lignin levels. Because of their altered cell wall composition, including elevated levels of cinnamaldehydes, both one-and three-year-old hpCAD wood showed enhanced saccharification yields upon harsh alkaline pretreatments (up to +85% and +77%, respectively). In contrast to previous field trials with poplars less severely downregulated for CAD, the hpCAD poplars displayed leaning phenotypes, early bud set, early flowering and yield penalties. Moreover, hpCAD wood had enlarged vessels, decreased wood density, and reduced relative and free water contents.  Our data show that the phenotypes of CAD-deficient poplars are strongly dependent on the environment and underpin the importance of field trials in translating basic research towards applications.

Research paper thumbnail of A poplar gene for caffeoyl-coenzyme A 3-O-methyltransferase (accession no. AJ223620)

Research paper thumbnail of Compensatory Guaiacyl Lignin Biosynthesis at the Expense of Syringyl Lignin in <i>4CL1</i>-Knockout Poplar

Plant Physiology, Mar 5, 2020

Research paper thumbnail of The effect of altered lignin composition on mechanical properties of CINNAMYL ALCOHOL DEHYDROGENASE (CAD) deficient poplars

Planta, Dec 21, 2017

Main conclusion CAD-deficient poplars enabled studying the influence of altered lignin compositio... more Main conclusion CAD-deficient poplars enabled studying the influence of altered lignin composition on mechanical properties. Severe alterations in lignin composition did not influence the mechanical properties. Wood represents a hierarchical fiber-composite material with excellent mechanical properties. Despite its wide use and versatility, its mechanical behavior has not been entirely understood. It has especially been challenging to unravel the mechanical function of the cell wall matrix. Lignin engineering has been a useful tool to increase the knowledge on the mechanical function of lignin as it allows for modifications of lignin content and composition and the subsequent studying of the mechanical properties of these transgenics. Hereby, in most cases, both lignin composition and content are altered and the specific influence of lignin composition has hardly been revealed. Here, we have performed a comprehensive micromechanical, structural, and spectroscopic analysis on xylem strips of transgenic poplar plants, which are downregulated for cinnamyl alcohol dehydrogenase (CAD) by a hairpin-RNA-mediated silencing approach. All parameters were evaluated on the same samples. Raman microscopy revealed that the lignin of the hpCAD poplars was significantly enriched in aldehydes and reduced in the (relative) amount of G-units. FTIR spectra indicated pronounced changes in lignin composition, whereas lignin content was not significantly changed between WT and the hpCAD poplars. Microfibril angles were in the range of 18°-24° and were not significantly different between WT and transgenics. No significant changes were observed in mechanical properties, such as tensile stiffness, ultimate stress, and yield stress. The specific findings on hpCAD poplar allowed studying the specific influence of lignin composition on mechanics. It can be concluded that the changes in lignin composition in hpCAD poplars did not affect the micromechanical tensile properties.

Research paper thumbnail of Behind the Scenes: The Impact of Bioactive Phenylpropanoids on the Growth Phenotypes of Arabidopsis Lignin Mutants

Frontiers in Plant Science, Sep 9, 2021

Research paper thumbnail of Two chemically distinct root lignin barriers control solute and water balance

Nature Communications, Apr 19, 2021

Research paper thumbnail of Next-generation sequencing as source of SNP and structural variants information to improve breeding programs in Populus nigra

HAL (Le Centre pour la Communication Scientifique Directe), Sep 20, 2010

Research paper thumbnail of Discovery of the biological role of PHENYLCOUMARAN BENZYLIC ETHER REDUCTASE (PCBER), one of the most abundant proteins in poplar xylem

Research paper thumbnail of Field trials with genetically engineered forest trees: past experiences and future prospects

HAL (Le Centre pour la Communication Scientifique Directe), Jun 8, 2015

Millions of markers but what is the message? Understanding and managing local adaptation in a cha... more Millions of markers but what is the message? Understanding and managing local adaptation in a changing climate

Research paper thumbnail of Field and saccharification performances of poplars severely downregulated in CAD1

New Phytologist

Summary Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzyma... more Summary Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hydrolysis. Glasshouse‐grown poplars severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE 1 (CAD1), the enzyme catalysing the last step in the monolignol‐specific branch of lignin biosynthesis, have increased saccharification yields and normal growth. Here, we assess the performance of these hpCAD poplars in the field under short rotation coppice culture for two consecutive rotations of 1 yr and 3 yr. While 1‐yr‐old hpCAD wood had 10% less lignin, 3‐yr‐old hpCAD wood had wild‐type lignin levels. Because of their altered cell wall composition, including elevated levels of cinnamaldehydes, both 1‐yr‐old and 3‐yr‐old hpCAD wood showed enhanced saccharification yields upon harsh alkaline pretreatments (up to +85% and +77%, respectively). In contrast with previous field trials with poplars less severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE (CAD), the hpCAD poplars display...

Research paper thumbnail of Forest Genomics and Biotechnology

Frontiers Research Topics, 2019

Research paper thumbnail of Incorporation of catechyl monomers into lignins: lignification from the non-phenolic end <i>via</i> Diels–Alder cycloaddition?

Research paper thumbnail of Mutation of the Inducible <i>ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE2</i> Alters Lignin Composition and Improves Saccharification

Plant Physiology, Oct 14, 2014

ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a... more ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a large number of CYTOCHROME P450 (CYP450) enzymes in Arabidopsis (Arabidopsis thaliana). Whereas ATR1 is constitutively expressed, the expression of ATR2 appears to be induced during lignin biosynthesis and upon stresses. Therefore, ATR2 was hypothesized to be preferentially involved in providing electrons to the three CYP450s involved in lignin biosynthesis: CINNAMATE 4-HYDROXYLASE (C4H), p-COUMARATE 3-HYDROXYLASE1 (C3H1), and FERULATE 5-HYDROXYLASE1 (F5H1). Here, we show that the atr2 mutation resulted in a 6% reduction in total lignin amount in the main inflorescence stem and a compositional shift of the remaining lignin to a 10-fold higher fraction of p-hydroxyphenyl units at the expense of syringyl units. Phenolic profiling revealed shifts in lignin-related phenolic metabolites, in particular with the substrates of C4H, C3H1 and F5H1 accumulating in atr2 mutants. Glucosinolate and flavonol glycoside biosynthesis, both of which also rely on CYP450 activities, appeared less affected. The cellulose in the atr2 inflorescence stems was more susceptible to enzymatic hydrolysis after alkaline pretreatment, making ATR2 a potential target for engineering plant cell walls for biofuel production.

Research paper thumbnail of Lignins with altered composition in the cell wall of transgenic plants

HAL (Le Centre pour la Communication Scientifique Directe), 1995

International audienc

Research paper thumbnail of Manipulation of lignin in trees

info:eu-repo/semantics/nonPublishe

Research paper thumbnail of Molecular marker and genetic engineering strategies to improve wood quality in poplar

Springer eBooks, 1999

The genetic improvement of trees is a slow process in comparison to that of annual crops. Tree br... more The genetic improvement of trees is a slow process in comparison to that of annual crops. Tree breeding though is important, given the ever increasing demand for wood and wood products. It is the aim of this paper to show that the classical genetic improvement of trees by breeding and selection can be assisted and accelerated by the application of molecular biology tools that have been developed over the last decade. First, it is now possible to develop a set of diagnostic markers that predict the characteristics of new hybrids soon after they have germinated, thus long before the traits are displayed. Second, genetic engineering allows the modification or addition of a given trait that would be difficult or impossible to obtain by conventional breeding. Case studies in both fields, with respect to disease resistance and wood quality, are presented.

Research paper thumbnail of Genetic modification of lignin biosynthesis in poplar to improve wood quality for the pulp and paper industry

info:eu-repo/semantics/nonPublishe

Research paper thumbnail of Reassessing the claimed cytokinin-substituting activity of dehydrodiconiferyl alcohol glucoside

Proceedings of the National Academy of Sciences

Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with rep... more Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with reported cytokinin-substituting and cell-division-promoting activity. Despite its claimed activity, DCG did not trigger morphological changes in Arabidopsis seedlings nor did it alter transcriptional shifts in cell division and cytokinin-responsive genes. In reinvestigating the bioactivity of DCG in its original setting, the previously described stimulation of tobacco callus formation could not be confirmed. No evidence was found that DCG is actually taken up by plant cells, which could explain the absence of any observable activity in the performed experiments. The DCG content in plant tissue increased when feeding explants with the DCG aglycone dehydrodiconiferyl alcohol, which is readily taken up and converted to DCG by plant cells. Despite the increased DCG content, no activity for this metabolite could be demonstrated. Our results therefore demand a reevaluation of the often-quoted cyt...

Research paper thumbnail of Downregulation of barley ferulate 5-hydroxylase dramatically alters straw lignin structure without impact on mechanical properties

Frontiers in Plant Science

Barley is a major cereal crop for temperate climates, and a diploid genetic model for polyploid w... more Barley is a major cereal crop for temperate climates, and a diploid genetic model for polyploid wheat. Cereal straw biomass is an attractive source of feedstock for green technologies but lignin, a key determinant of feedstock recalcitrance, complicates bio-conversion processes. However, manipulating lignin content to improve the conversion process could negatively affect agronomic traits. An alternative approach is to manipulate lignin composition which influences the physical and chemical properties of straw. This study validates the function of a barley ferulate 5-hydroxylase gene and demonstrates that its downregulation using the RNA-interference approach substantially impacts lignin composition. We identified five barley genes having putative ferulate 5-hydroxylase activity. Downregulation of HvF5H1 substantially reduced the lignin syringyl/guaiacyl (S/G) ratio in straw while the lignin content, straw mechanical properties, plant growth habit, and grain characteristics all rema...

Research paper thumbnail of Incorporation of catechyl monomers into lignins: lignification from the non-phenolic end via Diels–Alder cycloaddition?

Green Chemistry, 2021

Catechyl monomers 1-electron-oxidize and undergo radical coupling to produce benzodioxane units i... more Catechyl monomers 1-electron-oxidize and undergo radical coupling to produce benzodioxane units in lignin. Derived o-quinones undergo Diels–Alder reactions giving oxatricyclo and new benzodioxane products, but does this occur in lignification?.

Research paper thumbnail of Field and saccharification performances of poplars severely downregulated in <i>CAD1</i>

New Phytologist, Aug 9, 2022

 Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hy... more  Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hydrolysis. Greenhouse-grown poplars severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE 1 (CAD1), the enzyme catalyzing the last step in the monolignol-specific branch of lignin biosynthesis, have increased saccharification yields and normal growth.  Here, we assess the performance of these hpCAD poplars in the field under short rotation coppice culture for two consecutive rotations of one and three years.  While one-year-old hpCAD wood had 10% less lignin, three-year-old hpCAD wood had wild-type lignin levels. Because of their altered cell wall composition, including elevated levels of cinnamaldehydes, both one-and three-year-old hpCAD wood showed enhanced saccharification yields upon harsh alkaline pretreatments (up to +85% and +77%, respectively). In contrast to previous field trials with poplars less severely downregulated for CAD, the hpCAD poplars displayed leaning phenotypes, early bud set, early flowering and yield penalties. Moreover, hpCAD wood had enlarged vessels, decreased wood density, and reduced relative and free water contents.  Our data show that the phenotypes of CAD-deficient poplars are strongly dependent on the environment and underpin the importance of field trials in translating basic research towards applications.

Research paper thumbnail of A poplar gene for caffeoyl-coenzyme A 3-O-methyltransferase (accession no. AJ223620)

Research paper thumbnail of Compensatory Guaiacyl Lignin Biosynthesis at the Expense of Syringyl Lignin in <i>4CL1</i>-Knockout Poplar

Plant Physiology, Mar 5, 2020

Research paper thumbnail of The effect of altered lignin composition on mechanical properties of CINNAMYL ALCOHOL DEHYDROGENASE (CAD) deficient poplars

Planta, Dec 21, 2017

Main conclusion CAD-deficient poplars enabled studying the influence of altered lignin compositio... more Main conclusion CAD-deficient poplars enabled studying the influence of altered lignin composition on mechanical properties. Severe alterations in lignin composition did not influence the mechanical properties. Wood represents a hierarchical fiber-composite material with excellent mechanical properties. Despite its wide use and versatility, its mechanical behavior has not been entirely understood. It has especially been challenging to unravel the mechanical function of the cell wall matrix. Lignin engineering has been a useful tool to increase the knowledge on the mechanical function of lignin as it allows for modifications of lignin content and composition and the subsequent studying of the mechanical properties of these transgenics. Hereby, in most cases, both lignin composition and content are altered and the specific influence of lignin composition has hardly been revealed. Here, we have performed a comprehensive micromechanical, structural, and spectroscopic analysis on xylem strips of transgenic poplar plants, which are downregulated for cinnamyl alcohol dehydrogenase (CAD) by a hairpin-RNA-mediated silencing approach. All parameters were evaluated on the same samples. Raman microscopy revealed that the lignin of the hpCAD poplars was significantly enriched in aldehydes and reduced in the (relative) amount of G-units. FTIR spectra indicated pronounced changes in lignin composition, whereas lignin content was not significantly changed between WT and the hpCAD poplars. Microfibril angles were in the range of 18°-24° and were not significantly different between WT and transgenics. No significant changes were observed in mechanical properties, such as tensile stiffness, ultimate stress, and yield stress. The specific findings on hpCAD poplar allowed studying the specific influence of lignin composition on mechanics. It can be concluded that the changes in lignin composition in hpCAD poplars did not affect the micromechanical tensile properties.

Research paper thumbnail of Behind the Scenes: The Impact of Bioactive Phenylpropanoids on the Growth Phenotypes of Arabidopsis Lignin Mutants

Frontiers in Plant Science, Sep 9, 2021

Research paper thumbnail of Two chemically distinct root lignin barriers control solute and water balance

Nature Communications, Apr 19, 2021

Research paper thumbnail of Next-generation sequencing as source of SNP and structural variants information to improve breeding programs in Populus nigra

HAL (Le Centre pour la Communication Scientifique Directe), Sep 20, 2010

Research paper thumbnail of Discovery of the biological role of PHENYLCOUMARAN BENZYLIC ETHER REDUCTASE (PCBER), one of the most abundant proteins in poplar xylem

Research paper thumbnail of Field trials with genetically engineered forest trees: past experiences and future prospects

HAL (Le Centre pour la Communication Scientifique Directe), Jun 8, 2015

Millions of markers but what is the message? Understanding and managing local adaptation in a cha... more Millions of markers but what is the message? Understanding and managing local adaptation in a changing climate

Research paper thumbnail of Field and saccharification performances of poplars severely downregulated in CAD1

New Phytologist

Summary Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzyma... more Summary Lignin is one of the main factors causing lignocellulosic biomass recalcitrance to enzymatic hydrolysis. Glasshouse‐grown poplars severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE 1 (CAD1), the enzyme catalysing the last step in the monolignol‐specific branch of lignin biosynthesis, have increased saccharification yields and normal growth. Here, we assess the performance of these hpCAD poplars in the field under short rotation coppice culture for two consecutive rotations of 1 yr and 3 yr. While 1‐yr‐old hpCAD wood had 10% less lignin, 3‐yr‐old hpCAD wood had wild‐type lignin levels. Because of their altered cell wall composition, including elevated levels of cinnamaldehydes, both 1‐yr‐old and 3‐yr‐old hpCAD wood showed enhanced saccharification yields upon harsh alkaline pretreatments (up to +85% and +77%, respectively). In contrast with previous field trials with poplars less severely downregulated for CINNAMYL ALCOHOL DEHYDROGENASE (CAD), the hpCAD poplars display...

Research paper thumbnail of Forest Genomics and Biotechnology

Frontiers Research Topics, 2019

Research paper thumbnail of Incorporation of catechyl monomers into lignins: lignification from the non-phenolic end <i>via</i> Diels–Alder cycloaddition?

Research paper thumbnail of Mutation of the Inducible <i>ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE2</i> Alters Lignin Composition and Improves Saccharification

Plant Physiology, Oct 14, 2014

ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a... more ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a large number of CYTOCHROME P450 (CYP450) enzymes in Arabidopsis (Arabidopsis thaliana). Whereas ATR1 is constitutively expressed, the expression of ATR2 appears to be induced during lignin biosynthesis and upon stresses. Therefore, ATR2 was hypothesized to be preferentially involved in providing electrons to the three CYP450s involved in lignin biosynthesis: CINNAMATE 4-HYDROXYLASE (C4H), p-COUMARATE 3-HYDROXYLASE1 (C3H1), and FERULATE 5-HYDROXYLASE1 (F5H1). Here, we show that the atr2 mutation resulted in a 6% reduction in total lignin amount in the main inflorescence stem and a compositional shift of the remaining lignin to a 10-fold higher fraction of p-hydroxyphenyl units at the expense of syringyl units. Phenolic profiling revealed shifts in lignin-related phenolic metabolites, in particular with the substrates of C4H, C3H1 and F5H1 accumulating in atr2 mutants. Glucosinolate and flavonol glycoside biosynthesis, both of which also rely on CYP450 activities, appeared less affected. The cellulose in the atr2 inflorescence stems was more susceptible to enzymatic hydrolysis after alkaline pretreatment, making ATR2 a potential target for engineering plant cell walls for biofuel production.

Research paper thumbnail of Lignins with altered composition in the cell wall of transgenic plants

HAL (Le Centre pour la Communication Scientifique Directe), 1995

International audienc

Research paper thumbnail of Manipulation of lignin in trees

info:eu-repo/semantics/nonPublishe

Research paper thumbnail of Molecular marker and genetic engineering strategies to improve wood quality in poplar

Springer eBooks, 1999

The genetic improvement of trees is a slow process in comparison to that of annual crops. Tree br... more The genetic improvement of trees is a slow process in comparison to that of annual crops. Tree breeding though is important, given the ever increasing demand for wood and wood products. It is the aim of this paper to show that the classical genetic improvement of trees by breeding and selection can be assisted and accelerated by the application of molecular biology tools that have been developed over the last decade. First, it is now possible to develop a set of diagnostic markers that predict the characteristics of new hybrids soon after they have germinated, thus long before the traits are displayed. Second, genetic engineering allows the modification or addition of a given trait that would be difficult or impossible to obtain by conventional breeding. Case studies in both fields, with respect to disease resistance and wood quality, are presented.

Research paper thumbnail of Genetic modification of lignin biosynthesis in poplar to improve wood quality for the pulp and paper industry

info:eu-repo/semantics/nonPublishe