17th January
We often hear about the food-fuel conflict when discussing biofuels - but a breakthrough by British plant scientists has brought us one step closer to breeding multi-use crops, which produce both food and fuel.
The majority of the energy stored in plants is contained within the
woody parts, and billions of tons of this material are produced by
global agriculture each year in growing cereals and other grass crops,
but this energy is tightly locked away and hard to get at. This research
could offer the possibility of crops where the grain could be
used for food and feed and the straw, much of which is currently thrown away, used to produce energy
efficiently.
Professor Paul Dupree, of the University of Cambridge’s Department of Biochemistry, explains, “Unlike starchy grains, the energy stored in the woody parts of plants is locked away and difficult to get at. Just as cows have to chew the cud and need a stomach with four compartments to extract enough energy from grass, we need to use energy-intensive mechanical and chemical processing to produce biofuels from straw.
“What we hope to do with this research is to produce varieties of plants where the woody parts yield their energy much more readily – but without compromising the structure of the plant. We think that one way to do this might be to modify the genes that are involved in the formation of a molecule called xylan – a crucial structural component of plants.”
Xylan is an important, highly-abundant component of the plant cell wall, holding the other molecules in place to make a plant robust and rigid. This rigidity locks in the energy that we need to get at in order to produce bioenergy efficiently.
Grasses contain a substantially different form of xylan to other plants. The team wanted to find out what was responsible for this difference and so looked for genes that were turned on much more regularly in grasses than in the model plant Arabidopsis. Once they had identified the gene family in wheat and rice, called GT61, they were able transfer it into Arabidopsis, which in turn developed the grass form of xylan.
Dr Rowan Mitchell of Rothamsted Research continues, “As well as adding the GT61 genes to Arabidopsis, we also turned off the genes in wheat grain. Both the Arabidopsis plants and the wheat grain appeared normal, despite the changes to xylan. This suggests that we can make modifications to xylan without compromising its ability to hold cell walls together. This is important as it would mean that there is scope to produce plant varieties that strike the right balance of being sturdy enough to grow and thrive, whilst also having other useful properties such as for biofuel production.”
The tough, fibrous parts of plants are also an important component of our diet as fibre. Fibre has a well established role in a healthy diet, for example, by lowering blood cholesterol. The team have already demonstrated that changing GT61 genes in wheat grain affects the dietary fibre properties so this research also offers the possibility of breeding varieties of cereals for producing foods with enhanced health benefits.
Teachers who attended the Biology in the Real World lecture on the
future of biofuels at the ASE Annual Conference 2011 will remember Dr
Jen Bromley, one of the team that made this breakthrough, talking about
their research. Her presentation can be downloaded from the Society of
Biology website.
A group of teachers and scientists, including Jen Bromley, have produced a set of free practical protocols and teaching resources for looking at next-generation biofuels in the classroom.
Read more about the discovery on the University of Cambridge website.
Find out more about the teams of researchers working on next generation biofuels at the BBSRC Sustainable Bioenergy Centre.