From field to snack: development of a molecular marker-based method for the identification of the hazelnut (Corylus avellana L.) cultivar along the production chain

Commercial frauds concerning food ingredients are rather common because there are few checks and the identification of single constituents in a processed product is not easy due to the complexity of the matrix. This is particularly true when the quality of a food is due to the presence of a plant ingredient from a specific cultivar, selected for its superior quality and sometimes associated with a territory and a production chain. In this paper we present the development of an identification system, from field to snack, for the hazelnut cultivar ‘Tonda Gentile’ (syn. ‘Tonda Gentile delle Langhe’, ‘Tonda Gentile Trilobata’) sold 100% to industry for processing. ‘Tonda Gentile’ is the best payed hazelnut cultivar in the world, due to its recognized superior quality and low availability on the market (3-4% world production); it can be commercialized under the PGI ‘Nocciola Piemonte’ and is mostly sold to the kernel market, or as semi-finished product (chopped or ground into paste after roasting). In these cases, the identification of the cultivar is almost impossible. An additional difficulty for the identification of seeds is the due to the mandatory cross-pollination of the species. The work carried out has considered different types of molecular marker and strategies for the different steps of the production chain: nuclear SSR markers for the identification of the plant material in nursery and orchard, SNP/indel markers for clonal identification and valorization of selected clones, nSSR and chloroplast markers for the recognition of the cultivar in seed, chopped kernel, paste and processed products. NGS techniques were used for the re-sequencing of ‘Tonda Gentile’ clones and for isolating chloroplast markers through the genome skimming strategy.