Dr. Matthieu Bourdon –former researcher at Sainsbury Laboratory Cambridge University (SLCU) who is now at the Friedrich Miescher Institute for Biomedical Research– and colleagues have taken a different approach to understanding woody biomass.
They took callose, a polymer that is naturally occurring in some cell walls of plants, and successfully engineered it into the specialised secondary cell walls of plants — the wood. Published in Nature Plants, 2023, the research involving international collaborations across multiple institutes shows callose-enriched wood is much more easily converted into simple sugars and bioethanol than non-engineered wood.
Dr Bourdon first transformed the diminutive model plant, thale cress (Arabidopsis thaliana) to biosynthesise callose in its secondary walls. “We showed that the plants could accommodate a new polymer in their secondary cell walls without any negative impact on growth.” he said.
Switching to a fast-growing tree, the deciduous Hybrid Aspen Poplar (Populus tremula x tremuloides), the team found callose-enriched wood showed interesting new properties, like an increased hygroscopicity and porosity, which makes the polymers more accessible for extracting and converting into simpler building blocks like sugars or bioethanol.
“Understanding the ultrastructural effects of callose addition on the engineered wood was very challenging. The cutting-edge experiments performed by Paul and Ray Dupree’s teams in Cambridge and Warwick University are a cornerstone of this story. In fact, they surprisingly revealed that callose did not interact with other polymers but suggested that callose could act as a cell wall spacer attracting water. This approach inspired us to search for answers beyond our own expertise and establish further collaborations to produce this multi-disciplinary piece of research, ranging from genetic engineering, biochemistry and structural biology to material science.” Dr Bourdon said.
“We foresee that our engineered wood will benefit biomaterials and biofuels production relying on biomass deconstruction and polymer accessibility, such as packaging materials or even advanced biomaterials like cellulose nanofibrils and delignified wood. The next step is to carry out field trials to confirm our findings and to assess the performance of the callose-enriched trees under real forestry conditions. We also hope that our finding introducing a new polymer into wood will inspire other researchers to introduce other types of polymers for tailored applications.”