The Smart Carbohydrate Centre

The aim of our project is to produce new varieties of wheat and barley that contain starches with different properties from those found in current UK varieties. Starch is a very versatile carbohydrate, with many uses. It makes up 80-90% of wheat and barley grains, and is thus the main component of flour and of malts used in brewing and distilling. Pure starch, extracted from flour, is used to give thickness and texture to many processed food products, and is converted to glucose for use as a sweetener. It is also used in the manufacture of paper, textiles, pills, cosmetics, glues and packaging material. Each of these uses requires a different type of starch. For example, some food and industrial applications require a starch that forms a thick paste when cooked, others require a firm gel. The type of starch in flour can influence both the texture and the shelf life of bread, pasta and other baked goods. The type of starch in malts influences the cost of fermentation during beer and whisky production (some types of starch are much more easily converted to alcohol than others), and the quality of beer. The properties of a particular type of starch / whether it forms a gel or a paste and how quickly it is converted to alcohol, for example - depend on the structure of the chains of glucose molecules (polymers) of which it is composed. The structures of the polymers in starch from wheat and barley grown in the UK at present are all very similar. This means that bakers, brewers and distillers have no choice about the type of starch in their flour or malt. It also means that users of pure starch have to modify the structure of the polymers using chemicals or heat and pressure to make it suitable for their purposes. It is clear that the development of new varieties of wheat and barley, containing different types of starch, would be advantageous to many users of flour, malt and pure starch. It would provide new flours for bakers, and would potentially reduce the cost of fermentation to produce alcohol. This would be useful in beer and whisky production, and could also be critical in the cost-effectiveness of producing ethanol from wheat and barley as a 'green' fuel for cars. Wheat and barley varieties producing different types of starch would also reduce the need for modification of pure starch prior to its industrial use, and might open up new uses for starch / for example in the manufacture of low-cost, high-quality biodegradable 'plastics' to replace plastics made from oil and coal. We propose to develop new varieties of wheat and barley, bred for particular starch properties. We have already identified non-commercial varieties of barley that have very different types of starch. We will discover which genes in barley are responsible for this variation in starch properties, then use fast, conventional plant breeding methods to introduce these genes into varieties suitable for production in the UK. We will also introduce the same variation for starch properties into wheat varieties. We will monitor the properties of starch in our varieties as the breeding programme proceeds, and provide information and starch samples to a panel of UK users of flour, malt and starch (including representatives of commercial plant breeders, bakers, millers, brewers, distillers, producers of biofuels, researchers on healthy foods and manufacturers of biodegradable packaging). The panel will provide feedback on which types of starch are most valuable, and we will use this information to prioritise our work. The outcome, in three years time, will be near-commercial varieties of barley and wheat containing starches radically different from those presently available, each of which has commercial potential. These will be made available to the plant breeding industry for development into finished varieties for the UK market.

The nature of the starch in barley and wheat seeds is likely to influence profoundly the quality of flour and malt, the health-promoting properties of foods and the industrial value of extracted starch. However, little is known about the impact of genetic variation for starch properties on these uses of cereal grains, and this potential source of useful variation for breeding improved varieties of wheat and barley is not being exploited. To address this problem, we propose a systematic approach to the generation, characterisation and exploitation of variation in starch properties in barley and wheat. For barley we have a large collection of starch mutants, some of which have clear commercial potential. We will characterise the starches of these lines, and provide the information to an advisory Consortium of umbrella organisations of breeders and end-users of cereals. Advice from the Consortium will be used to prioritise which mutations to take forward. For the selected mutations we will use gene-based mapping and transcript-based cloning to discover the mutant genes, then introduce them into elite lines of barley using haplotype tags and mapped SSRs. The elite lines will be further analysed in collaboration with the Consortium at the BC2F4 stage. Major outputs will be pre-breeding material with starch characteristics of specific value to end-users, likely to include brewers, distillers, and manufacturers of food and biodegradable packaging and plastics. For wheat we will use TILLING to select knockout mutations in the three genes encoding isoamylase1, then combine the mutations in a single line. This mutant is expected to make starch/glucan of particular value in applications in which starch is converted to glucose, including bioethanol production. We will initiate further TILLING for mutations in other genes likely to affect starch properties, and characterise starches in mutant diploid wheats to provide more information on sources of variation.