CRISPR/Cas9 Gene Editing in the Marine Diatom Phaeodactylum tricornutum

Abstract

The establishment of the CRISPR/Cas9 technology in diatoms ( Hopes <i>et al.</i>, 2016 ; Nymark <i>et al.</i>, 2016 ) enables a simple, inexpensive and effective way of introducing targeted alterations in the genomic DNA of this highly important group of eukaryotic phytoplankton. Diatoms are of interest as model microorganisms in a variety of areas ranging from oceanography to materials science, in nano- and environmental biotechnology, and are presently being investigated as a source of renewable carbon-neutral fuel and chemicals. Here we present a detailed protocol of how to perform CRISPR/Cas9 gene editing of the marine diatom <i>Phaeodactylum tricornutum</i>, including: 1) insertion of guide RNA target site in the diatom optimized CRISPR/Cas9 vector (pKS diaCas9-sgRNA), 2) biolistic transformation for introduction of the pKS diaCas9-sgRNA plasmid to <i>P. tricornutum</i> cells and 3) a high resolution melting based PCR assay to screen for CRISPR/Cas9 induced mutations.