CRISPR/Cas9-Mediated Mutagenesis of Abdominal-A and Ultrabithorax in the Asian Corn Borer, Ostrinia furnacalis.

(1)

Background

Abdominal-A (Abd-A) and Ultrabithorax (Ubx) are homeotic genes that determine the identity and morphology of the thorax and abdomen in insects. The Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Pyralidae), is a devastating maize pest throughout Asia, the Western Pacific, and Australia. Building on previous knowledge, we hypothesized that the knockout of Abd-A and Ubx would disrupt the abdominal body planning in O. furnacalis. (2)

Methods

CRISPR/Cas9-targeted mutagenesis was employed to decipher the functions of these homeotic genes. (3)

Results

Knockout insects demonstrated classical homeotic transformations. Specifically, the mutagenesis of OfAbd-A resulted in: (1) Fused segments and segmental twist during the larval stage; (2) Embryonic lethality; and (3) The pleiotropic upregulation of other homeotic genes, including Lab, Pd, Dfd, Antp, and Abd-B. The mutagenesis of OfUbx led to: (1) Severe defects in the wing pads, which limited the ability of the adults to fly and mate; (2) Female sterility; and (3) The pleiotropic upregulation of other homeotic genes, including Dfd, Abd-B, and Wnt1. (4)

Conclusions

These combined results not only support our hypothesis, but they also strengthen the potential of using homeotic genes as molecular targets for the genetic control of this global insect pest.