Willow is a fast-growing species that is already used to produce wood chips and pellets for the renewable heating and power market but in future it could also help to produce biofuel through the extraction of fermentable sugars which are used to produce ethanol. It has been known for a while that when willows growing in the wild are blown sideways they tend to produce more sugars, but until now it has not been known why this happens.
Researchers at Imperial College, led by Dr Nicholas Brereton and Dr Michael Ray of the Department of Life Sciences, have now discovered that a particular genetic trait is responsible. When the tree is blown sideways its genes produce significant numbers of strengthening molecules as part of an attempt to redirect growth upwards.
“We've known for some time that environmental stresses can cause trees to naturally develop a slightly modified 'reaction wood’ and that it can be easier to release sugars from this wood” said Dr Brereton. “This is an important breakthrough, our study now shows that natural genetic variations are responsible for these differences and this could well be the key to unlocking the future for sustainable bioenergy from willow.”
The research was carried out under laboratory conditions at Imperial College’s Gro-dome facility in London city centre. The willows were grown at an angle of 45 degrees and then compared to willows which grow naturally straight upwards. The team then looked for the same effect among willows growing on the Isle of Orkney where strong winds cause the trees to lean at extreme angles. They discovered that the Orkney trees produce five times the amount of sugars found in willows grown in sheltered conditions at Rothamsted Research in Harpenden.
The study was conducted as part of the BioMASS project at BBSRC Sustainable Bioenergy Centre (BSBEC) in Swindon and has been published in the journal Biotechnology for Biofuels. The results indicate that biofuel crops such as willows could be grown in climatically challenging conditions where opportunities for growing food crops are limited, thereby helping to reduce food versus fuel conflicts.
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