Designing Lignin Structure for Modifying Pulping Performances, Application to Poplar Tree, 2000 Pulping / Process & Product Quality Conference Proceedings

M. Petit-Conil, C. Chirat, E. Guiney, W. Schuch, C. Lapierre, B. Pollet, I. Mila, W. Boerjan, L. Jouanin, J. C. Pilate--A poplar clone (Populus tremula x P. alba) was genetically engineered to down-regulate the activity of two genes encoding enzymes involved in the biosynthesis of lignin: caffeic acid O-methyltransferase (COMT) and cinnamyl alcohol dehydrogenase (CAD). Reference and transgenic lines were grown in the greenhouse and transferred to the field for studying their growth and producing sufficient wood for Kraft and mechanical pulping behaviour analysis. The results obtained with these four-year old trees confirmed the laboratory results. CAD down-regulation in poplar wood was an interesting alternative for chemical pulping (chemical savings, higher yield and better properties) but modified the bleachability of mechanical pulps, generating chromophores more resistant to alkaline peroxide oxidation. COMT down-regulation drastically and negatively affected the delignification but had no significant effect on mechanical pulp quality. Lignin structure analysis brought additional information that allowed explaining these pulping behaviors. Two field tests, implemented in France and in Great Britain, were compared.