Engineering structure and properties of poplar hemicelluloses (HemiPop)

Funding: Academy of Finland, WoodWisdom-Net programme
Collaboration: Prof. Ewa Mellerowicz, SLU, Sweden; Dr. Luc Saulnier, INRA Nantes, France
Project description:
Xylans are major wood component and thus expected to influence fiber properties. They are also potential renewable resource for bioenergy, biopolymers and other chemicals. Xylans are heteropolysaccharides whose properties vary according to the chemical structure. However, possibilities of modifying xylans in trees have until now not been explored. The project uses poplar as a model to produce analytical and biotechnological tools for analysis of xylans and for breeding of high value trees with modified xylan content, composition, and improved characteristics.Poplar is established model dicotyledon species whose whole genome is solved and it contains 23% xylan. Recent progress in elucidation of xylan biosynthesis in dicotyledon species, and in characterization of microbial xylan degrading enzymes enable us to use genetic engineering to affect xylan content and structure in poplar. Xylans are crucial for many desired pulp and paper properties but there are no detailed data on how chemical structure of xylans affects wood and fiber properties. It is suggested that substitution of xylan will affect its interaction with cellulose microfibrils, metal ions and lignin, and change its water adsorption and solubility. Thus changes in these parameters must affect secondary cell wall formation and further on fiber quality.Therefore we here propose to 1) generate transgenic poplars with modified xylan content and structure, 2) determine the impact of xylan modification on wood and fiber properties, and 3) develop chemical, enzymatic and immunological tools for elucidating xylan structure using native and transgenic wood.