Amy Newell

Conclusions

• Blue light is involved in cpRNP signalling
• cpRNPs are under both photoperiodic and circadian control
• Further insights will be gained from lab experiments with cpRNP mutants under blue light

 

Does the circadian clock control cpRNPs?

The proposed pathway of cpRNP expression and how the circadian clock might feed in 

The potential LHY binding site in the SEBF promoter identified on pattern locator

Chloroplast RNA binding proteins in the coordination of light inputs and photosynthetic responses

References: Cashmore, AR., Jarillo, JA., Wu, YJ., Liu, D.(1999) Cryptochromes: blue light receptors for plants and animals. Science, 284 (5415). [Online]. Available at: doi: 10.1126/science.284.5415.760. Griffin, J. H. C., Prado, K., Sutton, P. and Toledo-Ortiz, G. (2020). Coordinating light responses between the nucleus and the chloroplast, a role for plant cryptochromes and phytochromes. Physiologia Plantarum, 169 (4), pp.515–528. Michael, T. P., Breton, G., Hazen, S. P., Priest, H., Mockler, T. C., Kay, S. A. and Chory, J. (2008). A morning-specific phytohormone gene expression program underlying rhythmic plant growth. PLoS Biology, 6 (9). [Online]. Available at: doi:10.1371/journal.pbio.0060225. Mockler, T. C., Michael, T. P., Priest, H. D., Shen, R., Sullivan, C. M., Givan, S. A., Mcentee, C., Kay, S. A. and Chory, J. (2007). The diurnal project: Diurnal and circadian expression profiling, model-based pattern matching, and promoter analysis. In: Cold Spring Harbor Symposia on Quantitative Biology. 72. 2007. [Online]. Available at: doi:10.1101/sqb.2007.72.006. Nakai, M. (2018). New perspectives on chloroplast protein import. Plant and Cell Physiology, 59 (6). [Online]. Available at: doi:10.1093/pcp/pcy083. Raab, S., Toth, Z., De Groot, C., Stamminger, T. and Hoth, S. (2006). ABA-responsive RNA-binding proteins are involved in chloroplast and stromule function in Arabidopsis seedlings. Planta, 224 (4). [Online]. Available at: doi:10.1007/s00425-006-0282-4. Yanovsky, M. J. and Kay, S. A. (2002). Molecular basis of seasonal time measurement in Arabidopsis. Nature, 419 (6904). [Online]. Available at: doi:10.1038/nature00996. Acknowledgements: Thank you to my supervisor Gabriela Toledo-Ortiz and Jon Griffin for their help with this project.

cp29A was previously reported by Raab et al., (2006) to be under circadian clock control following a similar bioinformatics study using a different database.

-LHY is a component of the plant circadian clock. -In plants the circadian clock enables the plant to maintain a 24 hour cycle of expression regardless of the lighting conditions. -Photoreceptors provide lighting information to the clock to keep the 24 hour cycle going. -lhy mutations disrupts the clock and the expression of genes it controls.

-For functional chloroplasts to be built the nucleus and the chloroplast must coordinate their signalling -This is because the chloroplast was formed by the merging of a eukaryotic cell and a cyanobacterium -The nucleus now contains many genes that were once in the cyanobacterium

-One group of post transctiptional regulators are the Chloroplast RNA Binding Proteins (cpRNPs) - cpRNPs may be an important link between photoreceptors and chloroplast gene expression -cpRNPs are under Blue and Red photoreceptor control