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Dive into the research topics where Bart Ivens is active.

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Featured researches published by Bart Ivens.


Proceedings of the National Academy of Sciences of the United States of America | 2014

Improved saccharification and ethanol yield from field-grown transgenic poplar deficient in cinnamoyl-CoA reductase.

Rebecca Van Acker; Jean-Charles Leplé; Dirk Aerts; Veronique Storme; Geert Goeminne; Bart Ivens; Frédéric Legée; Catherine Lapierre; Kathleen Piens; Marc Van Montagu; Nicholas Santoro; Clifton E. Foster; John Ralph; Wim Soetaert; Gilles Pilate; Wout Boerjan

Significance In the transition from a fossil-based to a bio-based economy, bioethanol will be generated from the lignocellulosic biomass of second-generation biofuel crops, such as poplar. The lignin polymers in the plant cell walls represent the main factor determining the recalcitrance of biomass to enzymatic processing. We have grown genetically modified poplars, down-regulated for cinnamoyl-CoA reductase (CCR), an enzyme in the lignin biosynthetic pathway, in field trials in Belgium and France. We show that wood samples derived from the transgenic trees are more easily processed into ethanol. However, strong down-regulation also affected biomass yield. In conclusion, CCR down-regulation may become a successful strategy to improve biomass processing if the yield penalty can be overcome. Lignin is one of the main factors determining recalcitrance to enzymatic processing of lignocellulosic biomass. Poplars (Populus tremula x Populus alba) down-regulated for cinnamoyl-CoA reductase (CCR), the enzyme catalyzing the first step in the monolignol-specific branch of the lignin biosynthetic pathway, were grown in field trials in Belgium and France under short-rotation coppice culture. Wood samples were classified according to the intensity of the red xylem coloration typically associated with CCR down-regulation. Saccharification assays under different pretreatment conditions (none, two alkaline, and one acid pretreatment) and simultaneous saccharification and fermentation assays showed that wood from the most affected transgenic trees had up to 161% increased ethanol yield. Fermentations of combined material from the complete set of 20-mo-old CCR–down-regulated trees, including bark and less efficiently down-regulated trees, still yielded ∼20% more ethanol on a weight basis. However, strong down-regulation of CCR also affected biomass yield. We conclude that CCR down-regulation may become a successful strategy to improve biomass processing if the variability in down-regulation and the yield penalty can be overcome.


Theoretical and Applied Genetics | 2005

Intraspecific and interspecific genetic and phylogenetic relationships in the genus Populus based on AFLP markers

María Teresa Cervera; V. Storme; A. Soto; Bart Ivens; M. Van Montagu; O. P. Rajora; Wout Boerjan

Although Populus has become the model genus for molecular genetics and genomics research on forest trees, genetic and phylogenetic relationships within this genus have not yet been comprehensively studied at the molecular level. By using 151 AFLP® (AFLP® is a registered trademark of Keygene) markers, 178 accessions belonging to 25 poplar species and three interspecific hybrids were analyzed, using three accessions belonging to two willow species as outgroups. The genetic and phylogenetic relationships were generally consistent with the known taxonomy, although notable exceptions were observed. A dendrogram as well as a single most parsimonious tree, ordered the Populus sections from the oldest Leuce to the latest Aigeiros, a pattern consistent with their known evolutionary relationships. A close relationship between Populus deltoides of the Aigeiros section and species of the Tacamahaca section was observed and, with the exception of Populus wilsonii, between the species of the Leucoides, Tacamahaca, and Aigeiros sections. Populus nigra was clearly separated from its consectional P. deltoides, and should be classified separately from P. deltoides. The AFLP profiles pointed out to the lack of divergence between some species and revealed that some accessions corresponded with interspecific hybrids. This molecular study provides useful information about genetic relationships among several Populus species and, together with morphological descriptions and crossability, it may help review and update systematic classification within the Populus genus.


Theoretical and Applied Genetics | 2004

Ex-situ conservation of Black poplar in Europe: genetic diversity in nine gene bank collections and their value for nature development

Veronique Storme; A. Vanden Broeck; Bart Ivens; D. Halfmaerten; J Van Slycken; Stefano Castiglione; F. Grassi; Tiziana Fossati; Joan Cottrell; H.E. Tabbener; François Lefèvre; C. Saintagne; Silvia Fluch; V. Krystufek; K. Burg; S. Bordács; A. Borovics; K. Gebhardt; Barbara Vornam; A. Pohl; N. Alba; D. Agúndez; C. Maestro; E. Notivol; J. Bovenschen; B.C. van Dam; J.R. van der Schoot; Ben Vosman; Wout Boerjan; M.J.M. Smulders

Populus nigra L. is a pioneer tree species of riparian ecosystems that is threatened with extinction because of the loss of its natural habitat. To evaluate the existing genetic diversity of P. nigra within ex-situ collections, we analyzed 675 P. nigra L. accessions from nine European gene banks with three amplified fragment length polymorphism (AFLP) and five microsatellite [or simple sequence repeat (SSR)] primer combinations, and 11 isozyme systems. With isozyme analysis, hybrids could be detected, and only 3% were found in the gene bank collection. AFLP and SSR analyses revealed effectively that 26% of the accessions were duplicated and that the level of clonal duplication varied from 0% in the French gene bank collection up to 78% in the Belgian gene bank collection. SSR analysis was preferred because AFLP was technically more demanding and more prone to scoring errors. To assess the genetic diversity, we grouped material from the gene banks according to topography of the location from which the accessions were originally collected (river system or regions separated by mountains). Genetic diversity was expressed in terms of the following parameters: percentage of polymorphic loci, observed and effective number of alleles, and Nei’s expected heterozygosity or gene diversity (for AFLP). Genetic diversity varied from region to region and depended, to some extent, on the marker system used. The most unique alleles were identified in the Danube region (Austria), the Rhône region (France), Italy, the Rijn region (The Netherlands), and the Ebro region (Spain). In general, the diversity was largest in the material collected from the regions in Southern Europe. Dendrograms and principal component analysis resulted in a clustering according to topography. Material from the same river systems, but from different countries, clustered together. The genetic differentiation among the regions (Fst/Gst) was moderate.


The Plant Cell | 2014

Phenylcoumaran Benzylic Ether Reductase Prevents Accumulation of Compounds Formed under Oxidative Conditions in Poplar Xylem

Claudiu Niculaes; Kris Morreel; Hoon Kim; Fachuang Lu; Lauren S. McKee; Bart Ivens; Jurgen Haustraete; Bartel Vanholme; Riet De Rycke; Magnus Hertzberg; Jörg Fromm; Vincent Bulone; Andrea Polle; John Ralph; Wout Boerjan

This work reveals the biological function of phenylcoumaran benzylic ether reductase, one of the most abundant proteins in poplar wood. Its role is to reduce monolignol coupling products and to prevent accumulation of compounds formed under oxidative conditions. Phenylcoumaran benzylic ether reductase (PCBER) is one of the most abundant proteins in poplar (Populus spp) xylem, but its biological role has remained obscure. In this work, metabolite profiling of transgenic poplar trees downregulated in PCBER revealed both the in vivo substrate and product of PCBER. Based on mass spectrometry and NMR data, the substrate was identified as a hexosylated 8–5-coupling product between sinapyl alcohol and guaiacylglycerol, and the product was identified as its benzyl-reduced form. This activity was confirmed in vitro using a purified recombinant PCBER expressed in Escherichia coli. Assays performed on 20 synthetic substrate analogs revealed the enzyme specificity. In addition, the xylem of PCBER-downregulated trees accumulated over 2000-fold higher levels of cysteine adducts of monolignol dimers. These compounds could be generated in vitro by simple oxidative coupling assays involving monolignols and cysteine. Altogether, our data suggest that the function of PCBER is to reduce phenylpropanoid dimers in planta to form antioxidants that protect the plant against oxidative damage. In addition to describing the catalytic activity of one of the most abundant enzymes in wood, we provide experimental evidence for the antioxidant role of a phenylpropanoid coupling product in planta.


IUFRO Tree Biotechnology Conference 2011 : From genomes to integration and delivery | 2011

Science, society and biosafety of a field trial with transgenic biofuel poplars.

Rebecca Van Acker; Veronique Storme; Geert Goeminne; Bart Ivens; René Custers; Dirk Aerts; Wim Soetaert; John Ralph; Nicholas Santoro; Jean-Charles Leplé; Gilles Pilate; Wout Boerjan

Background Global warming, environmental disasters, and increasing oil prices have catalyzed a worldwide trend to use plant biomass as a renewable source for liquid biofuels and bio-based materials. Plant biomass can be processed into fermentable sugars by enzymatic depolymerization of the cell wall polysaccharides, followed by fermentation. However, the presence of lignin in the cell wall constitutes a major recalcitrance factor because it limits the accessibility of polysaccharidases to the cellulose microfibrils. To overcome this hurdle, plant biomass is pretreated in a costly and energyrequiring process. One approach to overcome the recalcitrance problem is to engineer lignin amount or alter its composition to make lignin more susceptible to chemical degradation [1]. Cinnamoyl-CoA reductase (CCR), the enzyme that converts feruloyl-CoA into coniferaldehyde, is considered the first enzyme in the monolignol-specific branch of the phenylpropanoid pathway. Poplar trees down-regulated in CCR have been produced in the early nineties and planted in a field trial in France to produce sufficient wood for small scale chemical pulping tests [2]. These trees had 20% lower lignin levels and relatively more cellulose per gram of wood [2]. Given that lignin is one of the main limiting factors limiting the conversion of plant biomass into fermentable sugars, and that poplar is considered as a promising second generation biofuel crop, we have re-grown these trees in the greenhouse and in the field, and evaluated wood produced from these trees by saccharification experiments. Methods Cinnamoyl-CoA reductase (CCR) expression was downregulated in poplar by sense and antisense strategies [2]. Transgenic trees were evaluated for lignin amount and composition [2] and for sugar release by saccharification assays [3]. After obtaining permission from the regulatory authorities, two transgenic lines were planted in a field trial in Belgium and two in a field trial in France, both under short rotation coppice culture to maximize biomass production. Wood was saccharified with and without acid pretreatment.


Genetics | 2001

Dense Genetic Linkage Maps of Three Populus Species (Populus deltoides, P. nigra and P. trichocarpa) Based on AFLP and Microsatellite Markers

María Teresa Cervera; Veronique Storme; Bart Ivens; Jaqueline Gusmão; Ben H Liu; Vanessa Hostyn; Jos Van Slycken; Marc Van Montagu; Wout Boerjan


Forest Ecology and Management | 2008

Structure of the genetic diversity in Black poplar (Populus nigra L.) populations across European river systems: consequences for conservation and restoration

M.J.M. Smulders; Joan Cottrell; François Lefèvre; J.R. van der Schoot; Paul Arens; Ben Vosman; Helen Tabbener; F. Grassi; Tiziana Fossati; Stefano Castiglione; V. Krystufek; Silvia Fluch; Kornel Burg; Barbara Vornam; A. Pohl; K. Gebhardt; N. Alba; D. Agúndez; C. Maestro; E. Notivol; R. Volosyanchuk; M. Pospíšková; S. Bordács; J. Bovenschen; B.C. van Dam; H.P. Koelewijn; D. Halfmaerten; Bart Ivens; J Van Slycken; A. Vanden Broeck


New Phytologist | 2013

Breeding with rare defective alleles (BRDA): a natural Populus nigra HCT mutant with modified lignin as a case study

Bartel Vanholme; Igor Cesarino; Geert Goeminne; Hoon Kim; Fabio Marroni; Rebecca Van Acker; Ruben Vanholme; Kris Morreel; Bart Ivens; Sara Pinosio; Michele Morgante; John Ralph; Catherine Bastien; Wout Boerjan


Canadian Journal of Forest Research | 2000

Improved AFLP analysis of tree species.

María Teresa Cervera; David L. Remington; J-M Frigerio; Veronique Storme; Bart Ivens; Wout Boerjan; Christophe Plomion


Genetic diversity in river populations of European Black poplar- implications for riparian ecosystem management; proceedings of an international symposium held in Szekszárd, Hungary, from 16-20 May, 2001 | 2002

Clonal propagation in Black Poplar (Populus nigra L.)

M.J.M. Smulders; J.R. van der Schoot; Bart Ivens; Veronique Storme; Stefano Castiglione; F. Grassi; Tiziana Fossati; J. Bovenschen; B.C. van Dam; Ben Vosman

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M.J.M. Smulders

Wageningen University and Research Centre

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D. Halfmaerten

Research Institute for Nature and Forest

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John Ralph

Great Lakes Bioenergy Research Center

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