Variabilité biologique des lignines

This review is strictly focussed on macromolecular chemistry views concerning the relations between the molecular structure of lignins, the possible self-organisation of lignin networks during plant cell walls lignification and the mechanical properties of woody plants and of their related products (pulp and papers, wood as composite material). Recent advances in genetic manipulations and biotechnological improvement of lignification cell walls and related products is emphasized as introduction. Then, the molecular organisation of lignins, the supramolecular aspects of lignification and, finally, some mechanisms of chemical morphogenesis and biomimetic synthesis are reviewed. A spatial-temporal model, combining activation and inhibition effects, is proposed to account the formation of lignin clusters observed during in situ lignification and in vitro synthesis of lignin polymers (DHP). This model and the corresponding molecular organisation hypothesis are discussed in relation to the so called 'self-organisation' effects, as depending on the cooperative interactions between cell wall components, including water, on autocatalytic initiation of lignin polymerisation by peroxidases, and on some physical and chemical intermolecular chain arrangement and rearrangement observed or suggested to occur during chemical pulping and mechanical deformation of wood. An English translation of this paper, more exactly expressed here in French, is in preparation for 'Internet open access', as the last of three reviews concerning the 'biological variability the states and processes of lignification' and the corresponding 'mechanical behaviour of woody plants and products'.