Towards a multiplex cereal traceability tool using padlock probe ligation on genomic DNA

Current EU regulations on the protection of products with certain characteristics (geographical indications and designations of origin) aim to ensure fair competition for producers and increased consumers’ trust. Within the European integrated research project TRACE analytical methods are being developed to allow the maintenance of specific regulations for PGIs (products of protected geographical indication) and PDOs (products of designated origin). An example within the project is the PGI wheat variety Farro della Garfagnana. The aim of the research was to develop a method to establish the purity of Farro della Garfagnana DNA in complex cereal mixtures. The combined approach of padlock probe ligation and multiplex microarray detection can identify possible admixtures. One undesired ‘contaminant’ for Farro della Garfagnana is common bread wheat (Triticum aestivum), containing the BBAuAuDD genome. Since Farro harbours the BBAuAu genome, absence of the D-genome rules out the presence of bread wheat. The current detection limit of this multimethod is at least 2.5% bread wheat in Farro.