University of Cambridge > Talks.cam > Plant Sciences Departmental Seminars > Light sensing in the Ocean: new perspectives from the study of the diatom photoreceptors

Light sensing in the Ocean: new perspectives from the study of the diatom photoreceptors

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The oceans cover 70% of the Earth’s surface, and the photosynthetic organisms living within the photic zone are responsible for around one half of global primary productivity. In the contemporary ocean, diatoms constitute a major component of the eukaryotic phytoplankton. Responsible for approximately 20% of global photosynthesis, diatoms are found in waters worldwide, wherever there is sufficient light and nutrients. The recent availability of whole genome sequences from representative species revealed that diatom genomes are made up of a unique cocktail of genes acquired during a complex evolutionary history, being diatoms derived from a secondary endosymbiosis between phototrophic and heterotrophic eukaryotes. These peculiar genomic features and metabolic pathways might help explaining diatom extraordinary adaptation capacities to a wide range of habitats.

The major object of our research is to characterize the mechanisms controlling diatom responses to light, one of the most important environmental signals for life on Earth. As on land, both irradiance and light quality change drastically in the different marine habitats, with blue light prevailing at increasing depths, this providing peculiar environmental condition for marine organisms. Diatoms display a suite of sophisticated responses (physiological, biochemical, and behavioural) to optimize their photosynthesis and growth under changing light conditions. However, the molecular mechanisms controlling diatom responses to light are still largely unknown. By using novel genomic information and by establishing fundamental genetic resources in the model species Phaeodactylum tricornutum, we are performing an extensive characterization of the light sensing mechanisms in diatoms. We found a plethora of blue light photoreceptors of the Cryptochrome and Aureochrome families and, surprisingly, also photoreceptors responding in red and far-red regions of the spectrum, e.g., Phytochrome (DPH). The biochemical and functional characterization of these photoreceptors is unveiling a diversification of light sensing and acclimation strategies in diatoms, raising novel hypotheses on the role of these proteins in controlling growth and adaptive responses in the marine context. A summary of our latest results will be presented.

This talk is part of the Plant Sciences Departmental Seminars series.

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