Direct allele introgression into pure chicken breeds using Sire Dam Surrogate (SDS) mating

Abstract

Poultry is the most abundant livestock species with over 60 billion chickens raised globally per year. The majority of chicken are produced from commercial flocks, however many indigenous chicken breeds play an important role in rural economies as they are well adapted to local environmental and scavenging conditions. The ability to make precise genetic changes in chicken will permit the validation of genetic variants responsible for climate adaptation and disease resilience, and the transfer of beneficial alleles between breeds. Here, we generate a novel inducibly sterile surrogate host chicken. Introducing donor genome edited primordial germ cells into the sterile male and female host embryos produces adult chicken carrying only exogenous germ cells. Subsequent direct mating of the surrogate hosts, Sire Dam Surrogate (SDS) mating, recreates the donor chicken breed carrying the edited allele in a single generation. We demonstrate the introgression and validation of two feather trait alleles, Dominant white and Frizzle into two pure chicken breeds using the SDS surrogate hosts.

Cultivation and characterization of primordial germ cells from blue layer hybrids (Araucana crossbreeds) and generation of germline chimeric chickens

“…Until now, there is no way to predict the efficiency of germline transmission of one PGC lineage. The most promising approach to improve the transmission efficiency of donor PGCs are genetically engineered, sterile recipients 13 , 19 . Further investigations concerning the transcriptomic differences between male and female or gonadal and blood-derived PGCs should be done, for example by RNA-sequencing.…”

“…The diploid PGCs are replication competent and allow for extensive cell expansion, thus potentially allowing the preservation of the whole genome from minute quantities of starting material. The reconstitution of a rare breed or rare alleles with the help of PGCs becomes attractive particularly now, when genetically sterile chicken can act as surrogate hosts for PGC transplantation 13 , 19 . Through transmitting the genetic information, the potential of PGCs for avian gene preservation is tremendous.…”

Direct cryopreservation of poultry/avian embryonic reproductive cells: A low-tech, cost-effective and efficient method for safeguarding genetic diversity

“…Male dissociated gonadal cells were mixed with B/B compound and injected directly into ED 2.5 iCaspase9 embryos. B/B compound activates the iCaspase9 transgene leading to the selective ablation of the endogenous germ cells (Ballantyne, Woodcock et al 2021). Female embryonic gonads were thawed, dissociated and MACS-purified using an anti SSEA-1 antibody before injection.…”

“…iCaspase9 surrogate hosts of both sexes produced gametes and offspring only deriving from donor PGCs. Direct mating of the surrogate hosts (Sire Dam Surrogate (SDS) mating) produced genetically pure breed offspring entirely derived from the exogenous PGCs ((Ballantyne, Woodcock et al 2021), Ballantyne, in press).…”

Evidence for and localization of proposed causative variants in cattle and pig genomes

“…The generation of gene-edited calves that carry the polled allele (using the TALEN technology) has confirmed that it causes hornlessness [ 149 ]. The generation of gene-edited chickens with the CRISPR-Cas9 system has demonstrated that the PMEL17 dominant white allele causes white pigmentation of the feathers and the KRT75 frizzled allele causes brittle frizzled feathers [ 150 ]. Niu et al [ 151 ] used CRISPR-genome editing to inactivate all of the porcine endogenous retroviruses (PERV) in a porcine primary cell line and generated PERV-inactivated pigs via somatic cell nuclear transfer.…”