TY - JOUR T1 - Editing of the urease gene by CRISPR-Cas in the diatom <em>Thalassiosira pseudonana</em> JF - bioRxiv DO - 10.1101/062026 SP - 062026 AU - Amanda Hopes AU - Vladimir Nekrasov AU - Sophien Kamoun AU - Thomas Mock Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/07/18/062026.abstract N2 - Background: CRISPR-Cas is a recent and powerful edition to the molecular toolbox which allows programmable genome editing. It has been used to modify genes in a wide variety of organisms, but only two alga to date. Here we present a methodology to edit the genome of T. pseudonana, a model centric diatom with both ecological significance and high biotechnological potential, using CRISPR-Cas.Results: A single construct wa assembled using Golden Gate cloning. Two sgRNAs were used to introduce a precise 37nt deletion early in the coding region of the urease gene. A high percentage of bi-allelic mutations (≤ 61.5%) were observed in clones with the CRISPR-Cas construct. Growth of bi-allelic mutants in urea led to a significant reduction in growth rate and cell size compared to growth in nitrate.Conclusions: CRISPR-Cas can precisely and efficiently edit the genome of T. pseudonana. The use of Golden Gate cloning to assemble CRISPR-Cas constructs gives additional flexibility to the CRISPR-Cas method and facilitates modifications to target alternative genes or species. ER -