An Efficient Method for the Plating of Haploid and Diploid Emiliania huxleyi on Solid Medium¹

Emiliania huxleyi is a globally important coccolithophore and one of the most successful eukaryotic organisms in the modern oceans. Despite a large body of work on this organism, including the sequencing of its genome, the tools required for forward and reverse functional genetic studies are still undeveloped. Here we present an optimized method for the clonal isolation of E. huxleyi by plating on solid medium. We demonstrate the utility of this method for a variety of strains including haploid, calcifying-diploid, and noncalcifying diploid strains. We show that, in contrast to previous studies, no changes in cell ploidy status occur when the cells are plated. Our method will greatly aid attempts to elucidate the genetic basis of the remarkable physiology of E. huxleyi by forward and reverse genetic approaches.