This project focuses on the light signalling pathways regulating chloroplast development with an emphasis on the tetrapyrrole pathway leading to chlorophyll synthesis.
To optimise photosynthesis plants have to receive and process information about their surrounding light environment. They do this using a range of different photoreceptors including the blue light-absorbing cryptochromes and the phytochromes, which absorb red and far-red light. Both photoreceptor families are important in the regulation of a wide range of developmental responses in plants from germination to growth and flowering. They are also important in regulating chloroplast development (or biogenesis) and this is the focus of this research project. Successful chloroplast biogenesis during seedling de-etiolation is critical to plant survival and requires the careful co-ordination of gene expression from both the nuclear and chloroplast (plastid) genomes. Genes encoding chloroplast proteins are under the control of the phytochromes and the cryptochromes and we have investigated these signalling pathways focusing on the regulation of the chlorophyll (tetrapyrrole) synthesis pathway, a key pathway during chloroplast development. Recently we have shown that the phytochrome-interacting PIF proteins are important repressors of chloroplast development in the dark, where they interact with the gibberellin-responsive DELLA family of growth regulators to optimise this key process. Ongoing experiments on light signalling pathways use both Arabidopsis and, most recently, in wheat where we are testing the role of PIFs in light and gibberellin regulation of plant architecture.