A project at the U.S. Department of Energy’s BioEnergy Science Center is looking at tension wood, which forms naturally in hardwood trees in response to bending stress, and which is known to possess unique features that make it desirable as a bioenergy feedstock. Although individual elements of tension wood have been studied previously, the new project is the first to systematically characterize the wood and link its properties to sugar release. These plant sugars, known as cellulose, are fermented into alcohol for use as biofuel.
“There has been no integrated study of tension stress response that relates the molecular and biochemical properties of the wood to the amount of sugar that is released,” said Udaya Kalluri, a co-author on the study. “Tension wood in poplar trees has a special type of cell wall that is of interest because it is composed of more than 90 per cent cellulose, whereas wood is normally composed of 40 to 55 per cent cellulose. If you increase the cellulose in your feedstock material, then you can potentially extract more sugars as the quality of the wood has changed. Our study confirms this phenomenon.”
Although tension wood itself is not considered to be a viable feedstock, insight gleaned from studying it could be used to design and select more suitably tailored bioenergy crops, the researchers said.