Branding and tracing seaweed: Development of a high-resolution genetic kit to identify the geographic provenance of Alaria esculenta

Abstract

Global seaweed production increased rapidly in the past 50 years, mostly in Asia. Recently seaweed aquaculture has been attracting more attention worldwide because of its potential as a form of sustainable agriculture that provides food, feed, fertiliser, bio-stimulants and other valuable products. Quality characteristics of seaweeds are species-dependent, influenced by the genetic makeup of the individual, and by the environmental conditions where the seaweeds are grown. Those two factors largely depend on their place of origin. Traceability in terms of geographic provenance would therefore add commercial value to seaweed products . Here we describe the development of a method to identify/certify the place of origin of the blown alga Alaria esculenta . We identified Single Nucleotide Polymorphisms (SNPs) on the nuclear, plastid and mitochondrial genomes by analysing whole-genome sequences of individuals originated from Ireland, Northern Ireland, Faroe Islands, Greenland, Norway and Atlantic Canada. Multi-dimensional scaling (MDS) plots of the nuclear SNPs, but not of the organellar SNPs, showed a clear separation of individual samples by the country of origin. We then identified country-specific nuclear SNPs and designed a set of cleaved amplified polymorphic sequence (CAPS) assays to detect two or three of specific SNPs per country. The SNPs were tested on individuals, including those whose genome sequence had not been determined, and were shown to successfully identify individual's country of origin. This method allows accurate determination of the geographic provenance of Alaria esculenta . This tool could form the base for branding seaweed products with certified origin, and for the development of mass identification kits using metabarcoding . It also has the potential to be used to monitor seaweed farms for invasion of non-native varieties of a seaweed species, and, more broadly, to monitor effects of climate change on the diversity of seaweed populations. • Nuclear SNPs distinguish the geographical location of Alaria esculenta strains. • Organellar SNPs failed to distinguish geographical location of the strains. • Country-specific nuclear SNPs allowed developing CAPS assays. • The method can be deployed for both ecological and industrial applications.