Efficient genome editing in the olive fruit fly, Bactrocera oleae

The olive fruit fly, Bactrocera oleae, causes great damage to the quality and quantity of olive production worldwide. Pest management approaches have proved difficult for a variety of reasons, a fact that has brought about a need for alternative tools and approaches. Here we report for the first time in B. oleae the development of the clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9) gene editing tool, using the well-known eye colour marker gene scarlet. Two synthetic guide RNAs targeting the coding region of the scarlet gene were synthesized and shown to work efficiently in vitro. These reagents were then microinjected along with purified Cas9 protein into early-stage embryos. Successful CRISPR-induced mutations of both copies of the scarlet gene showed a striking yellow eye phenotype, indicative of gene disruption. Multiple successful CRISPR events were confirmed by PCR and sequencing. The establishment of an efficient CRISPR-based gene editing tool in B. oleae will enable the study of critical molecular mechanisms in olive fruit fly biology and physiology, including the analysis of insecticide resistance mechanisms and the discovery of novel insecticide targets, as well as facilitate the development of novel biotechnology-based pest control strategies.