The successful application of primordial germ cells (PGCs) is an ideal method for generating gene-edited birds. However, barriers to efficient DNA transfection in PGCs lead to low transfection efficiency, limiting the generation of genetically modified chickens. The current study utilized chemical transfection and electroporation methods to determine the optimal transfection conditions for the PGC line under feeder- and serum-free medium. Among the tested methods, the Lonza electroporation system exhibited the highest transduction efficiency, with a previously unreported rate of 71.13 ± 1.26%. Optimal transfection conditions were achieved using 4 µg of DNA and 100 µL of Entranster^TM-E in 1 × 10⁶ PGCs. Furthermore, the optimal electroporation conditions resulted in low cell death and normal expression of pluripotency-related genes, highlighting the low cytotoxicity. The resulting electroporation models were then used to deliver the enhanced green fluorescent protein (EGFP) gene to the Z chromosome with a Cas9-gRNA plasmid, achieving a 7-day insertion efficiency of 14.63 ± 1.07%. Our study highlights the vast potential of electroporation technology for the transfection of PGCs.

This study aimed to establish an efficient and precise cytosine base editor (CBE)-mediated knockout system in chicken somatic cells and primordial germ cells (PGCs). PGCs are pivotal for generating genome-edited chickens, but low transfection efficiency limit their application. Unlike CRISPR/Cas9, CBEs achieve precise C-to-T conversion without DNA double-strand breaks or donor templates, making them safer for avian genome engineering. We used CBEs to introduce premature stop codons in exon 1 of the sex-determining AR and DMRT1 genes for targeted knockout. Among 12 screened sgRNAs, sgRNA6 (AR, 94.67 ± 6.66%) and sgRNA9 (DMRT1, 6.67 ± 6.51%) performed best in DF-1 cells; in PGCs, their editing efficiencies reached 51.0% and 91.0%, respectively. No off-target mutations were detected in edited DF-1 cells. These findings confirm that CBE-mediated knockout is highly efficient and safe in chicken somatic and germ cells, providing a robust tool for avian genome editing.