LAUSR

Squid is an important seafood resource in Asian and European countries. Due to the different nutritional and market values of various squid species, substitutions between species often occur for higher profits. In this study, a species-specific PCR assay was developed for genetic discrimination of eight commercially important squid species from each other, based on the single nucleotide polymorphism (SNP) sites exploited from mitochondrial cytochrome oxidase subunit I (COI) sequences. The introduction of additional mismatches both in the forward and reverse primers ensured absolute allele specificity despite a moderate annealing temperature. The eight squid species can be clearly discriminated from each other by simplex PCR, and the developed multiplex species-specific PCR assay can detect 1% of intentional adulteration of non-target squid species into target species down to the 0.1 ng level of template DNA without PCR optimization. Therefore, the present study provides a simple and reliable genetic assay for identification of squid origin either in single or mixed species, and the developed assay will be useful in correct labeling and quality control of squid products.