The alga Dunaliella revisited: Looking back and moving forward with model and production organisms

The green alga Dunaliella has long been a model organism for studying abiotic stress responses, and its commercial use for β-carotene production is still being expanded. In the context of the special issue on “The Alga Dunaliella”, we present an overview of the research status of Dunaliella. We highlight some of the existing challenges and provide an outlook for future research. Importantly, the issue of Dunaliella taxonomy has not yet been resolved. As confirmation of the species delineation still awaits a concerted community effort, we propose that reference strains should be designated for some species. Due to the existing resources, we suggest this designation for D. salina be the strain CCAP19/18. In addition, we suggest as references for the halophilic D. viridis the type strain SAG 44.89 and for the marine D. tertiolecta the type strain CCAP19/6B. Such reference strains will be required to consolidate already-reported results and to enable novel, fundamental, and applied research questions to be addressed as well as to open the door to informed strain engineering. We highlight some novel developments that are still not widely known, such as the recent publication of the genome of D. salina. In spite of these challenges, many “omics” studies are increasing knowledge at the molecular level, and the concomitant refinement of the molecular toolbox for Dunaliella species is expected to provide an understanding of the metabolic networks, which will make metabolic engineering and biorefinery approaches commercially viable.