We evaluated the frequency of targeted mutagenesis induced by the Cas9-gUMPS1 RNP complex in the absence of selection. To achieve that, P. tricornutum cells were bombarded with a dose response of 0, 2, 4 and 8 µg of Cas9-gUMPS1 complex. As positive controls, different amounts of a monoallelic mutant strain carrying a 1nt deletion at the gUMPS1 target site were mixed with WT cells to get cell-to-cell ratios of 100%, 10%, 1% and 0, 1% and 0%.