Improving the digestibility of barley straw could increase its potential as a second generation biofuel, said Claire Halpin, professor of plant biology and biotechnology at the University of Dundee.
Using straw as a biofuel would avoid the food versus fuel debate made when using grain for bioethanol production, as well as increasing the competitiveness of the crop, she explained.
But the sugars within the stem that could be fermented into bioethanol are much more inaccessible than in grain. “It is because they are in the walls of plant cells, which are a bit like reinforced concrete. The long chain sugars are the steel rods, and embedded in lignin, which is the glue that sticks it together. But lignin is hard to digest, so it is not easy to get to the sugars.”
However, variation in the composition of lignin exists in nature, so as part of the BBSRC’s sustainable bionenergy centre (BSBEC), researchers at the university and SCRI are screening barley varieties for mutations that modify lignin without affecting standing power or disease resistance.
“We’ve identified one mutation in the gene that makes lignin in a variety called Bowman that produces 17% less lignin, and changes the colour of the lignin to orange, for example,” Prof Halpin explained. “It has a potentially useful benefit.”
Another part of the project was investigating which genes were important in controlling how much sugar you get from the straw, she said. “That knowledge is transferable to other crops, such as wheat and miscanthus.”
Significant headway in understanding the genetics involved in using straw as a biofuel had been made already in the five-year project, she added. “This is really do-able, but it will take five to 15 years before we see commercial processes.”