Chemical interrogation: a new, systems approach to starch metabolism in germinating barley seeds

Lead Research Organisation: John Innes Centre
Department Name: Contracts Office


The aim of this project is to provide information that will help in the breeding of new, improved types of wheat and barley for food and for brewing. Wheat and barley seeds contain up to 80 percent of their dry weight as starch. This starch is normally broken down to sugars when the seeds germinate, and the sugars are used by the embryo of the seed for growth to produce the new seedling. The timing and extent of starch breakdown in the seed has very important implications for the production of both wheat flour and barley malt. The quality of wheat seeds for the production of flour depends on a high starch content. In a wet summer, the process of starch breakdown can start while the seed is still on the plant, resulting in a very poor quality of flour. The process of barley malting depends on precise control of starch breakdown, so that when yeast is added the correct amount of sugar is available for alcohol production. In spite of years of breeding for the 'ideal' barley for making malt, brewers still see room for improvement. Efforts to improve the quality of wheat and barley seeds are held up by a lack of knowledge about how starch is broken down in these seeds. Although a great deal is known about some of the individual enzymes involved in starch breakdown, we do not know how they operate together during germination. We want to discover which enzymes are necessary for starch breakdown in the seed, and exactly what they contribute to this process. We will do this investigating how starch breakdown is altered in seeds that are supplied with specific inhibitors of enzymes thought to be involved in starch breakdown, and seeds of mutant barley plants in which some of the enzymes are missing from the seeds. This will give us new information about the process of starch breakdown, and will enable us to advise wheat and barley breeders on producing improved wheat and barley varieties in the future.


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