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Session 2 – Cell Wall, Biomass and Biofuels S2.2- Disrupting the cinnamyl alcohol dehydrogenase 1 (BdCAD1) gene leads to altered lignification and improved saccharification in Brachypodium distachyon Madeleine Bouvier d'Yvoire 1, Richard Sibout 1, Oumaya Bouchabke 1, Olivier Darracq 1, Sebastien Antelme 1, Leonardo Gomez 2, Laurent Cezard 1, Catherine Lapierre 1, Lise Jouanin 1. 1Institut Jean-Pierre Bourgin (IJPB), UMR1318 INRA-AgroParisTech, 78026 Versailles, FR 2Centre for Novel Agricultural Products, University of York, York Y010 5 YW, UK Madeleine.Bouvier-Dyvoire@versailles.inra.fr Abstract Second generation biofuels using fermentable sugars from plant cell walls could provide an answer to the augmentation of global energy needs with a limited impact on food resources. As grasses show attractive features for this purpose, Brachypodium distachyon was recently pointed as a valuable model plant for temperate grass species. Lignins are major secondary cell wall polymers that derive from the polymerization of monolignols. They confer rigidity and hydrophobicity to plant cell walls. However, they also constitute an obstacle to most industrial processes targeting cellulose or hemicellulose, and they need to be removed by costly, polluting and energy demanding processes. Plants with altered lignification often display enhanced saccharification yields (enzymatic conversion of cellulose into fermentable sugars). In order to identify cell wall compositions more susceptible to saccharification, the Sodium Azide and EMS mutageneized lines from the Versailles Brachypodium collection were screened based on the colour of their stems. Indeed, orange, red or brown vascular elements are often associated with altered lignification. The mutants so identified, hereafter named « brown stem » (bs), were analyzed and several showed improved saccharification. Among them, mutants in a CAD candidate gene (cinnamyl alcohol dehydrogenase, involved in the last step of the monolignol biosynthesis pathway) were found, that have the highest saccharification yields. These lines possess a significative decrease in CAD activity and in their lignin contents. Their lignins are also enriched in free phenolic groups, sinapaldehyde units and resistant bounds. Functional complementation of Arabidopsis thaliana and Brachypodium cad mutants confirmed the function of BdCAD1, and RNAi CAD lines are being selected in order to analyse the effects of the silencing of several CAD genes. References Vanholme R, Moreel K, Ralph J, Boerjan W (2008) Lignin engineering. Current Opinion in Plant Biology 11 :278-285 Marita JM, Vermerris W, Ralph J, Hatfield RD (2003) Variations in the cell wall composition of Maize brown midrib mutants. Journal of Agricultural and Food Chemistry 51 : 1313-1321 Sibout R, Eudes A, Mouille G, et al. (2005) CINNAMYL ALCOHOL DEHYDROGENASE-C and -D Are the Primary Genes Involved in Lignin Biosynthesis in the Floral Stem of Arabidopsis. The Plant Cell 17 : 2059-2076 Youn B, Camacho R, Moinuddin SGA, et al. (2006) Crystal structures and catalytic mechanism of the Arabidopsis cinnamyl alcohol dehydrogenases AtCAD5 and AtCAD4. Organic & Biomolecular Chemistry 4 : 1687-1697 Keywords Brachypodium, lignin, cinnamyl alcohol dehydrogenase, saccharification 17
Session 2 – Cell Wall, Biomass and Biofuels S2.3- Identification of Brachypodium mutants defective in silicon uptake Emiko Murozuka, Pia Haugaard Nord-Larsen, Inge Skrumsager Møller, Thomas Paul Jahn and Jan Kofod Schjoerring Plant and Soil Science Laboratory, Department of Agriculture and Ecology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C emikomu@life.ku.dk Abstract Silicon (Si) is a beneficial element for higher plants. The positive effect of Si is related to the fact that Si increases the mechanical strength and rigidity of the cell walls, thereby stimulating growth and contributing to the alleviation of biotic and abiotic stresses. On the other hand, Si accumulation decreases the degradability of plant residues, which may cause resistance to treatments for saccharification in cellulosic ethanol production (Van Soest 2006). In addition, high content of Si in plant residues increases the amount of ash during the combustion of biomass. There is accordingly a strong interest in reducing Si accumulation in plant materials used for bioenergy purposes (Gressel 2008). Si transport mechanisms have so far been studied in rice. Three Si transporters, Lsi1, Lsi2 and Lsi6 have been identified and characterized. Lsi1 and Lsi6 belong to aquaporins while Lsi2 is a secondary active anion transporter (Ma and Yamaji 2008, Yamaji et al., 2008). Lsi1 and Lsi2 are involved in uptake of Si, while Lsi6 functions in the distribution of Si in the shoots. In our study, Brachypodium distachyon has been used to investigate the mechanisms of uptake and distribution of Si in grasses. Phenotypic screening using germanium (Ge) was carried out in a Brachypodium mutant population of about 1200 lines in order to identify mutants which were defective in Si uptake. After the screening, about 30 lines were selected as candidates. So far one of the lines was found to be defective in Lsi1. Characterization of the protein revealed that Brachypodium Lsi1 transports Si as well as other substances such as arsenite and boric acid, which corresponds with the function of rice Lsi1. The mutant plant will be characterized after backcrossing with the wild type focusing on degree of Si accumulation and the incorporation of Si in the cell wall. Further screening and identification will be continued in order to find more mutants in Si transporters. References Gressel J (2008) Transgenics are imperative for biofuel crops. Plant Sci 174: 246–263 Ma J.F, Yamaji N (2008) Functions and transport of silicon in plants. Cell Mol Life Sci 65: 3049-3057 Van Soest P.J (2006) Rice straw, the role of silica and treatments to improve quality. Anim. Feed Sci. Tech. 130: 137–171 Yamaji N, Mitatni N, Ma J.F (2008) A transporter regulating silicon distribution in rice shoots. Plant Cell 20:1381-1389 Keywords silicon transporter, aquaporin, cell wall 18
Page 2 and 3: Acknowledgements: Institut National
Page 4 and 5: Contents Programme 4 Oral presentat
Page 6 and 7: Wednesday 19 th October, 2011 11:00
Page 8 and 9: Friday 21 st October, 2011 Biotic a
Page 10 and 11: ORAL COMMUNICATIONS 9
Page 12 and 13: Session 1 - Evolution and Natural V
Page 20 and 21: Session 2 - Cell Wall, Biomass and
Page 26 and 27: Session 3 - Tools and Bioengineerin
Page 32 and 33: Session 4 - Biotic and Abiotic Stre
Page 42 and 43: Session 5 - Plant Development, Meta
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Session 4 - Biotic and Abiotic Stre
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Session 5 - Plant Development, Meta
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Session 5 - Plant Development, Meta
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S: Speakers’ abstracts P: Posters
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LIST OF PARTICIPANTS 75
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BOUCHABKE-COUSSA Oumaya INRA IJPB I
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GIRALDO Patricia E.T.S.I. Agronomos
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MARION-POLL Annie INRA IJPB Institu
Page 84 and 85:
RENAULT Hugues CNRS - IBMP Institut
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WARD Eric Two Blades Foundation, P.
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