About 3to4

Fundamental differences in photosynthetic metabolism have been surprisingly unexploited as a means to increase plant productivity and thus provide more food and fuel, and this applies particularly to C₄ photosynthesis, despite the fact that it is the photosynthetic pathway found in maize, one of the world’s major, and most productive, crops. Overall, if the characteristics of C₄ photosynthesis were introduced into C₃ crops, this would increase yield, reduce land area needed for cultivation, and limit both irrigation and fertiliser applications because of their improved productivity and efficiency in use of water and nitrogen. The occurrence of C₄ photosynthesis in multiple lineages also provides us with a deep biological resource to increase our understanding of the process.

The specific aims of the 3 to 4 project are to:

• Identify genes that control elaboration of the bundle sheath in C₃ species. Currently, although C₄ photosynthesis requires enhanced development of bundle sheath cells, no genes associated with bundle sheath development have been identified. This means we do not know how bundle sheath development is altered in C₄ leaves, and so we cannot manipulate it.
• Define the differences in gene expression between mesophyll and bundle sheath cells of closely related C₃ and C₄ plants.  Until we know the extent to which gene expression is altered in mesophyll and bundle sheath cells of C₄ plants compared with C₃ plants, it is not possible to assess the extent to which we have engineered characteristics of C₄ photosynthesis into C₄ leaves.
• Identify the important post-translational modifications that are associated with efficient functioning of the C₄ cycle. Currently we have an incomplete knowledge of these modifications to enzymes that are important for the C₄ cycle.
• Increase photosynthesis by placing elements of C₄ photosynthesis into C₃ crops. Study the natural photorespiratory by-pass in plants such as Moricandia with the longer term endeavour of integrating C₄ photosynthesis into C₃ crops.
• Strengthen the European expertise in 3to4 conversion in order that European scientists retain their pre-eminent position in this field. 3to4 will provide international leadership in this area, both in terms of cutting edge science, and also in training the next generation of researchers and will utilise appropriate training opportunities (e.g. summer schools) aimed at early-career stage researchers and to build European research capacity in this area.
• A further priority of this group is to build a vibrant interface between photosynthesis researchers and the broader community of stakeholders including Industry.
• Harness the new fundamental knowledge generated in the programme to inform support tools on decisions of how to engineer 3to4.
• Enable the better design of experiments across globe on ways to engineer 3to4.