Better Grasses

Grasses are usually herbaceous plants with narrow leaves growing from the base. They include the true grasses, as well as the sedges (Cyperaceae) and the rushes. The true grasses include cereals, bamboo and the grasses of lawns (turf) and grassland. Researchers from the Biotechnology and Biological Sciences Research Council (BBSRC) Sustainable Bioenergy Center (BSBEC) have discovered a family of genes that could help breed grasses with improved properties for dietary use and bioenergy uses. The genes are important in the development of the fibrous, woody parts of grasses, like rice and wheat. The team hopes that by understanding how these genes work, they might for example be able to breed varieties of cereals where the fibrous parts of the plants confer additional dietary benefits or crops whose straw requires less energy-intensive processing in order to produce biofuels. Uses for grasses include as food (grain, sprouted grain, shoots or rhizomes), drink (beer, whiskey), pasture for livestock, thatch, paper, fuel, clothing, insulation, construction, sports turf, basket weaving and many others.  Grass is literally the breadbasket of the world. The new research was carried out by a team from the University of Cambridge and Rothamsted Research, which receives strategic funding from BBSRC. Their findings are published January 17 in the journal Proceedings of the National Academy of Sciences (PNAS). 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 multi-use crops where the grain could be used for food and feed and the straw used to produce energy efficiently. This is crucial if we are to ensure that energy can be generated sustainably from plants, without competing with food production. Biofuels can be in competition with food stuffs since both are derived from the same or similar vegetative source.  Fermentation of sugars derived from wheat, corn, sugar beets, sugar cane, molasses and any sugar or starch is used to produce ethanol, a common base biofuel.   Professor Paul Dupree, of the University of Cambridge, 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... 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 tough walls that surround plant cells. It holds the other molecules in place and so helps to make a plant robust and rigid. This rigidity is important for the plant, but locks in the energy that we need to get at in order to produce bioenergy efficiently. Grasses contain a substantially different form of xylan as compared 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. 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.