Sexing by gene editing in pigs is an alluring alternative to the surgical castration of piglets as the male-specific boar taint remains a major obstacle in pork production. In mice, the SRY-gene was first described as a genetic developmental switch for the male phenotype. The knockout of the murine SRY-gene by TALEN suppressed testis development in the fetal gonadal ridges and generated a female phenotype. In addition, the knockout of the 5’ flanking region of the rabbit SRY gene results in a similar phenotype as in mice. In our study, we aimed to generate a knockout of the porcine SRY gene to investigate its role in sex determination in pigs. For the first time, we successfully generated a knockout of the SRY gene in pigs by microinjection of two CRISPR/Cas9 complexes targeting the centrally located “high mobility group” domain (HMG) of the SRY gene. Frameshift mutations within the porcine HMG domain resulted in the development of complete female external and internal genitalia in genetically male piglets. Moreover, we further confirmed the function of the HMG box as the main functional domain for male sex development, as the introduction of a deletion within the 5’ flanking region of the HMG domain was not associated with sex reversal in the resulting offspring. These results pave the way to generate boars that produce female offspring only and provide a potential solution to avoid surgical castration.
Audience Take Away Notes:
- The role of the porcine SRY gene in sex determination
- Use of intracytoplasmic microinjection of CRISPR/Cas system and/or cloning to induce sex reversal in pigs
- Concept to generate female-producing boars