Diatom Molecular Research Comes of Age: Model Species for Studying Phytoplankton Biology and Diversity

Diatoms are the most diverse group of algae with at least 100,000 species. Contributing approximately 20% of annual global carbon fixation, they underpin major aquatic food webs and drive global biogeochemical cycles. Over the last two decades, Thalassiosira pseudonana and Phaeodactylum tricornutum have become the most important references for diatom molecular research, ranging from cell biology to ecophysiology, because of their rapid growth rates, small genomes and the cumulative wealth of associated genetic resources. To ascertain the significance of the evolutionary divergence of diatoms, additional references are emerging such as Fragilariopsis cylindrus and Pseudo-nitzschia multistriata. Here, we describe how functional genomics and reverse genetics have contributed to our understanding of this important class of microalgae in the context of evolution, cell biology and metabolic adaptations. Our review will also highlight promising areas of investigation into the diversity of these photosynthetic organisms, including the discovery of new molecular pathways governing the life of secondary plastid-bearing organisms in aquatic environments.