PRIMARY CARBON METABOLISM

Project Leaders: Kay Denyer, Cliff Hedley, Matthew Hills, Steve Rawsthorne and Trevor Wang.

This theme focuses on the metabolism of starch and sucrose in higher plants.

The biogenesis of starch granules. Our work concerns the generation of the precursor ADPglucose, the organisation of the semi-crystalline granule matrix, and the role of starch synthases, starch-branching enzymes and debranching enzymes. It utilises mutant plants and natural genetic variation (particularly in cereals, in collaboration with the Department of Crop Genetics) to explore the evolution and functional significance of differences between plant species in the ways in which starch granules are synthesised. This work underpins attempts to develop new types of starch that can replace petrochemicals as raw materials for industry. (Kay Denyer, Alison Smith).

The relationship between starch granule structure and the functional properties of starch. This work exploits genetic variation in peas selected in earlier studies at JIC and held in our germplasm collections. It has many practical applications - for example in production of specialised, biodegradable starch films. The research is in collaboration with the Institute of Food Research in Norwich. (Cliff Hedley).

The pathway of starch degradation in leaves at night. In collaboration with other research groups, we are using forward and reverse genetic approaches in Arabidopsis to elucidate this pathway. Our work has overturned the established picture, and led to the discovery of new proteins involved in the process. We are exploring whether the picture emerging for Arabidopsis is also true for crop plants - for example the leaves of forage maize. (Alison Smith).

Primary carbon metabolism in relation to development in seeds and legume root nodules. We are using an extensive collection of Arabidopsis mutants lacking enzymes of sucrose metabolism to explore systematically the role of sucrose in seed development - for example in relation to seed expansion, embryo nutrition, and the developmental change from cell division to storage oil accumulation in the embryo. The work involves advanced imaging and tissue sampling techniques and isotope feeding experiments. It produces data of relevance to the breeding of improved varieties of oilseed rape. The metabolism of these plants is being explored with state-of-the art equipment for analysing the molecular composition of plant material. (Steve Rawsthorne, Matthew Hills, Trevor Wang).

Research on the nitrogen-fixing root nodules of legumes aims to discover the interplay between the provision of carbon from the plant to the nitrogen-fixing bacteria within the nodule, and the provision of nitrogen from the bacteria to the plant. It uses our collections of legume mutants lacking components of the nitrogen fixation process, and of starch and sucrose metabolism and involves a wider European dimension (INTEGRAL). (Trevor Wang)