Diatoms are the world's most diverse group of algae, comprising at least 100,000 species. Contributing 20% of annual global carbon fixation, they underpin major aquatic food webs and drive global biogeochemical cycles. Over the past two decades, breakthroughs in genomics and ecosystem biology, as well as the development of genetic resources in diatom model species, have contributed to our understanding of this important class of microalgae in the context of evolution, cell biology, and metabolic adaptations.

Major objective of our research is to identify the mechanisms controlling diatom growth and distribution within the ecological niches and oceanic provinces they inhabit. As diatoms rely on light, both as their main source of energy and for information about their environment, we are performing a comprehensive characterization of light-regulated processes in these microalgae. By integrating physiological, biophysical, biochemical and genome-wide molecular approaches in the model species Phaeodactylum tricornutum and Cyclotella cryptica, we are contributing to characterize some of the diatom specific photoacclimation features. We uncovered the key function played by members of the light-harvesting complex stress-related family, LHCXs, in the regulation of photoprotective mechanisms. We also showed that these proteins influences natural variability in photoresponse, as evidenced in ecotypes isolated from different latitudes that display different LHCX protein levels. By characterizing diverse photoreceptor genes and by assessing their distribution and possible activity in the environment, we are also revieling peculiar light sensing abilities in diatoms. Altogether, these findings indicate that light-driven processes are key players of diatom functional biodiversity. They also emphasize that integration of laboratory and environmental studies are both timely and essential to understand the life of phototrophs in complex ecosystems and to properly assess the consequences of environmental changes on aquatic environments globally.

Falciatore A, Jaubert M, Bouly JP, Bailleul B, Mock T. Diatom Molecular Research Comes of Age: Model Species for Studying Phytoplankton Biology and Diversity. Plant Cell. 2022, 32:547-572.

Falciatore A and Mock T Eds. “The Molecular Life of Diatoms” Book. Springer, 2022.