Gene Editing: an Opportunity for Sustainable Aquaculture

Recent biotechnological technologies have allowed the development of new approaches to apply genetic engineering to non-model organisms. New sequencing technologies allow fast and cost effective analysis of whole genomes, transcriptomes or epigenomes. Functional studies became now feasible for many following the introduction of the CRISPR-Cas9 methodology, which can specifically target and mutate genes in virtually any organism, allowing studies on the genetics of key traits. The recent publication of the Atlantic salmon reference genome further allows to elucidate the genetic and molecular mechanisms behind these traits. 

In the recent years several GWAS have revealed that single SNPs in the genomes of wild an cultivated salmonids can explain important traits such as time of maturity and disease resistance. Further studies need to aim at elucidating how single nucleotide exchanges can alter key traits for aquaculture including growth, reproduction and disease resistance. There is therefore a need to develop technologies which can induce single nucleotide changes. This can be achieved by the combination of gene editing and homologous recombination as has been shown in zebrafish and mammals. So far knock out by gene editing has been established in both rainbow trout and Atlantic salmon. However, both species have a long generation time so new approaches are very much desired. Double allelic knock in by homologous recombination already in the F0 will allow to boost up functional studies in these species. However, due to the current low efficiencies of homologous recombination this can be challenging. We have successfully established a methodology using pigmentation as a tracer for double allelic mutations in Atlantic salmon, this methodology can be further explored for knocking in traits of interest.

Being able to substitute functional single bases in the genome of salmonids may thereby offer a non-transgenic alternative not only for salmon breeding enhancement, but to understand which are the functional mechanisms behind key sustainable traits such as disease resistance, welfare, food metabolism and reproduction.