Mytilus galloprovincialis is highly recognized as an important aquaculture species, and Spain, with a production close to 200,000 tonnes per year, is the main M. galloprovincialis producer in the EU. This valuable seafood product is particularly susceptible to fraudulent practices due to several factors including the high number of species involved and the complexity and globalization of the food chain. Seafood authentication includes species and geographical origin identification, and it is a major concern for consumers and seafood producers. In this sense, European Union regulation (EU) No 1169/2011 requires that consumers are appropriately informed about the food they consume.
Different analytical procedures can be used f or sea food authentication and DNA-based methodologies have been revealed as the ideal approach to address the identification of species and have also proven to be useful for geographical origin verification , mainly due to the sensitivity, accuracy and DNA stability. The use of the P olymerase C hain Reaction (PCR) technique as a routine method has also enhanced the expansion of DNA-based tools in control laboratories for seafood authenticity. DNA barcoding b ased on Sanger sequencing has demonstrated to be a very useful authentication tool for species identification, but it results inconvenient to identify multiple Single Nucleotide Polymorphism (SNP) required for the identification of geographical origin. Instead, N ext G eneration S equencing (NGS), or second-generation sequencing, may solve this issue . Unfortunately, NGS applications are slow, expensive, and need well-equipped laboratories and bioinformatic skills to analyse the large amounts of sequence data and therefore is not portable nor user-friendly at all for rapid testing . In this regard, Third-generation sequencing (also known as long-read sequencing), such as Oxford Nanopore, can be applied to solve this constraint since one of its key advantages includes portability and sequencing speed.
In a previous work , we used thousands of genome SNPs, obtained by Restriction site-Associated DNA sequencing (RAD-seq), to provide a detailed genetic structure of the M. galloprovincialis
. This genetic information was eventually refined and reduced to a panel of ten SNPs which allowed the correct origin assignment of mussels to the Atlantic or Mediterranean area s. This final panel has been successfully implemented in the MinIONTM , a small and portable third-generation sequencer (Oxford Nanopore Technologies), encouraging more frequent testing with a quicker turnaround time and at a lower price.