Closing the gaps in the C4 cycle

C4 photosynthesis is a variant of normal photosynthesis that confers improved light, nitrogen, and water use efficiency. These enhancements are achieved by physically separating the reactions of photosynthesis between two cells to concentrate CO2 so that it can be more efficiently converted into sugar. The fact that C4 photosynthesis is split between two cells means that multiple transmembrane transport steps are required for it to operate. Although we know the enzymes that catalyse the biochemical reactions of the C4 pathway, some of the transporters that carry out the transmembrane transport steps have evaded discovery, and thus we cannot engineer C4 photosynthesis into non-C4 plants to capitalise on the enhanced light, nitrogen, and water use efficiency of the pathway. In this talk I will discuss how we discovered a key transporter of the C4 cycle and how this finally provides a biochemical blueprint for engineering C4 photosynthesis into non-C4 plants.