Pathways to neo-functionalization: the past and future of strigolactone signalling

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Hormonal signalling pathways are vitally important in the regulation of plant growth and development. Strigolactones (SLs) and 'KAI2-Ligand' (KL) are closely related hormonal signals that regulate specific aspects of development, including shoot branching and seed germination. In flowering plants, including most crop plants, SL and KL act through very closely related signalling pathways to regulate development. In evolutionary terms, SL signalling appears to have arisen by duplication of the KL signalling pathway. Indeed, in non-flowering plants, there is evidence that the SL and KL signalling pathways overlap at least partially. This raises very intriguing questions as to whether the signalling pathways in flowering plants are truly separate, or whether they partially or even fully overlap.This project aims to assess to what extent the SL and KL signalling pathways in flowering plants are separated from each other, and to understand at a molecular level how this 'specificity' arises. The main hypothesis we will test is that the perception of SL and KL by receptor proteins is highly specific, but that the mechanisms by which these pathways regulate development are very similar and at least partially overlapping. To address this question, the project will bring together a wealth newly available genomic data, with a powerful experimental system in the model plant Arabidopsis thaliana. By assessing how SL and KL signalling have evolved throughout the 500 million year history of land plants, we can formulate hypotheses regarding the specificity of these pathways, which we can then test in the context of Arabidopsis lateral root development. This project will allow us to understand how plants could be bred to enhance or diminish certain effects of SL or KL in order to improve yields. In summary, by analysing the past and present of SL and KL signalling, we can define possibilities for future crop improvement.