To edit the duck genome by HDR-directed integration of the EGFP gene into the duck host genome in combination with SMGT using CRISPR/Cas9. Methods. HDR-mediated gene of green fluorescent protein (EGFP) was crried out by the combined action of four plasmids. The pX330 contained the Cas9 gene. Two plasmids contained sgRNA genes: pBR322-sgRNA1 and pBR322-sgRNA2. The pBR322-HDR-EGFP plasmid was constructed to contain the DNA vector with left homologous sequence part(LHP), the EGFP gene coding sequences and the right homologous sequence part(RHP). The DNA sequence data for designing the HDR-EGFPinsert and sgRNA 1 and sgRNA 2 were taken from the genome DNA sequence of Anas platyrhynchos Spindlin 1 (SPIN1) gene. Twenty four ducks (13 males and 11 females) of the Shaoxing breed were used for this experiment. The sperm transfection was performed using Lipofectamine 2000. Results. Thirty one ducks were obtained, 19 of which carried the EGFP gene. F2 analysis revealed that 16 ducks (F1) (14 females and 2 males) transmitted the transgene DNA to their offsprings. Thus 27.6 % (56/203) of F2 descendants were positive for the transgene DNA construct. Conclusions. Exogenous DNA was successfully inserted into the duck genome.

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The goose is an economically important poultry species and was one of the first to be domesticated. However, studies on population genetic structures and domestication in goose are very limited. Here, we performed whole genome resequencing of geese from two wild ancestral populations, five Chinese domestic breeds, and four European domestic breeds. We found that Chinese domestic geese except Yili geese originated from a common ancestor and exhibited strong geographical distribution patterns and trait differentiation patterns, while the origin of European domestic geese was more complex, with two modern breeds having Chinese admixture. In both Chinese and European domestic geese, the identified selection signatures during domestication primarily involved the nervous system, immunity, and metabolism. Interestingly, genes related to vision, skeleton, and blood-O2 transport were also found to be under selection, indicating genetic adaptation to the captive environment. A forehead knob characterized by thickened skin and protruding bone is a unique trait of Chinese domestic geese. Interestingly, our population differentiation analysis followed by an extended genotype analysis in an additional population suggested that two intronic SNPs in EXT1, an osteochondroma-related gene, may plausibly be sites responsible for knob. Moreover, CSMD1 and LHCGR genes were found to be significantly associated with broodiness in Chinese domestic geese and European domestic geese, respectively. Our results have important implications for understanding the population structure and domestication of geese, and the selection signatures and variants identified in this study might be useful in genetic breeding for forehead knob and reproduction traits.