2022, Jaubert, Marianne, Duchêne, Carole, Kroth, Peter G., Rogato, Alessandra, Bouly, Jean-Pierre, Falciatore, Angela

Diatoms are prominent microalgae that proliferate in a wide range of aquatic environments. Still, fundamental questions regarding their biology, such as how diatoms sense and respond to environmental variations, remain largely unanswered. In recent years, advances in the molecular and cell biology of diatoms and the increasing availability of genomic data have made it possible to explore sensing and signalling pathways in these algae. Pivotal studies of photosensory perception have highlighted the great capacity of diatoms to accurately detect environmental variations by sensing differential light signals and adjust their physiology accordingly. The characterization of photoreceptors and light-dependent processes described in this review, such as plastid signalling and diel regulation, is unveiling sensing systems which are unique to these algae, reflecting their complex evolutionary history and adaptation to aquatic life. Here, we also describe putative sensing components involved in the responses to nutrient, osmotic changes, and fluid motions. Continued elucidation of the molecular systems processing endogenous and environmental cues and their interactions with other biotic and abiotic stress signalling pathways is expected to greatly increase our understanding of the mechanisms controlling the abundance and distribution of the highly diverse diatom communities in marine ecosystems.

2008, Bowler, Chris, Allen, Andrew E., Badger, Jonathan H., Grimwood, Jane, Jabbari, Kamel, Kuo, Alan, Maheswari, Uma, Martens, Cindy, Maumus, Florian, Otillar, Robert P., Rayko, Edda, Salamov, Asaf, Vandepoele, Klaas, Beszteri, Bank, Gruber, Ansgar, Heijde, Marc, Katinka, Michael, Mock, Thomas, Valentin, Klaus, Verret, Fréderic, Berges, John A., Brownlee, Colin, Cadoret, Jean-Paul, Chiovitti, Anthony, Choi, Chang Jae, Coesel, Sacha, De Martino, Alessandra, Detter, John Chris, Durkin, Colleen, Falciatore, Angela, Fournet, Jérome, Haruta, Miyoshi, Huysman, Marie J. J., Jenkins, Bethany D., Jiroutova, Katerina, Jorgensen, Richard E., Joubert, Yolaine, Kaplan, Aaron, Kröger, Nils, Kroth, Peter G., La Roche, Julie, Lindquist, Erica, Lommer, Markus, Martin Jézéquel, Véronique, Lopez, Pascal J., Lucas, Susan, Mangogna, Manuela, McGinnis, Karen, Medlin, Linda K., Montsant, Anton, Oudot Le Secq, Marie-Pierre, Napoli, Carolyn, Obornik, Miroslav, Schnitzler Parker, Micaela, Petit, Jean-Louis, Porcel, Betina M., Poulsen, Nicole, Robison, Matthew, Rychlewski, Leszek, Rynearson, Tatiana A., Schmutz, Jeremy, Shapiro, Harris, Siaut, Magali, Stanley, Michele S., Sussman, Michael R., Taylor, Alison R., Vardi, Assaf, Dassow, Peter von, Vyverman, Wim, Willis, Anusuya, Wyrwicz, Lucjan S., Rokhsar, Daniel S., Weissenbach, Jean, Armbrust, E. Virginia, Green, Beverley R., Van de Peer, Yves, Grigoriev, Igor V.

Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one-fifth of the primary productivity on Earth. The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology. Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.