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Published: 12 March 2015

CT scanning reveals why tilting trees produce better biofuel

Surrey researchers have used medical imaging techniques to explore why making willow trees grow at an angle can vastly improve their biofuel yields.

Using micro-CT scans, the team showed that the trees respond to being tilted by producing a sugar-rich gelatinous fibre, which helps them stay upright.

Willows are suitable for widespread cultivation as biofuels because they produce large quantities of accessible sugar, are fast-growing and can tolerate harsh environmental conditions, such as windy slopes and poor soil. In fact, trees grown in harsher conditions or polluted soil can even produce better biofuel because the sugar they produce is more accessible, requiring less energy to harvest it.

Growing the willow trees at a 45-degree angle simulates this natural stress, encouraging  the trees to produce up to five times more sugar than plants grown normally. But exactly why and how this happens has not been clear until now.

The project was led by researchers at Imperial College London, who worked with experts at the Natural History Museum, the University of Surrey and Rothamsted Research Centre to use X-ray micro-computed tomography (CT scanning) to examine the willow's growth through high resolution 3D images.

This enabled them to see the changes in the willow at a cellular level and how they affected the plant's growth. They found that tilted willows prolonged the life of certain cells in order to produce a sugar-rich, or gelatinous, fibre, to help them stay upright. The team was able to measure how much longer the cells needed to stay alive to produce the special fibre.

Professor Richard Murphy, Director of the Centre for Environmental Strategy and Chair of Life Cycle Assessment at the University of Surrey said: “We are delighted to publish our novel findings on the 3D tissue patterning in willows in BMC Plant Biology. This knowledge is vital for our understanding of how basic plant biomass structure and composition influences the biorefining of woody plants into valuable and sustainable second generation bio-based products, including biofuels.”

The research was funded by the Biotechnology and Biological Sciences Research Council. The next step for the team will be to use even higher resolution CT scanning to investigate the gelatinous fibres in more detail. The aim will be to measure how much of the fibre is produced by different plants, which will help identify which species of willow are likely to be the world's best 2nd generation biofuel producers.

Read the full paper in BMC Plant Biology.

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