Recent advances in adult injection-based insect genome editing have enabled genetic manipulation of a wide range of insect species, including those previously considered difficult or even impervious to genetic modification. However, achieving efficient knock-in remains a significant challenge with this approach. Here, we demonstrate that fusing a HUH endonuclease tag to Cas9 significantly enhances both non-homologous end joining (NHEJ)-mediated knockout and homology-directed repair (HDR)-mediated knock-in via adult injection. This fusion increased knockout efficiency by up to fivefold in the beetle Tribolium castaneum through adult injection, likely due to its previously unrecognized nuclear localization activity. It also improved single-stranded oligodeoxynucleotide (ssODN)-mediated knock-in efficiency, which we attribute to its characteristic ssDNA-tethering activity. To evaluate its versatility, we tested the HUH-tagged Cas9 in conventional embryo injection, which significantly enhanced HDR-mediated knock-in of an epitope tag in cricket and milkweed bug embryos. Our findings establish the HUH-tag as a versatile platform for improving both NHEJ- and HDR-based genome editing, providing a robust framework to advance genetic engineering across a broad spectrum of arthropods.
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Generating and testing the efficacy of reagents for CRISPR/Cas9 homology directed repair-based manipulations in Tribolium
Abstract CRISPR/Cas9 manipulations are possible in many insects and ever expanding. Nonetheless, success in one species and techniques developed for it are not necessarily applicable to other species. As such, the development and expansion of CRISPR-based (clustered regularly interspaced short palindromic repeats) genome-editing tools and methodologies are dependent upon direct experimentation. One useful technique is Cas9-dependent homologous recombination, which is a critical tool for studying gene function but also for developing pest related applications like gene drive. Here, we report our attempts to induce Cas9 homology directed repair (HDR) and subsequent gene drive in Tribolium castaneum (Herbst; Insecta: Coleoptera: Tenebrionidae). Utilizing constructs containing 1 or 2 target gRNAs in combination with Cas9 under 2 different promoters and corresponding homology arms, we found a high incidence of CRISPR/Cas9 induced mutations but no evidence of homologous recombination. Even though the generated constructs provide new resources for CRISPR/Cas9 modification of the Tribolium genome, our results suggest that additional modifications and increased sample sizes will be necessary to increase the potential and detection for HDR of the Tribolium genome.
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- Award ID(s):
- 1928781
- PAR ID:
- 10546029
- Editor(s):
- Park, Yoonseong
- Publisher / Repository:
- Oxford Academic
- Date Published:
- Journal Name:
- Journal of Insect Science
- Volume:
- 24
- Issue:
- 4
- ISSN:
- 1536-2442
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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