Use of microsatellite markers for genetic traceability of Girgentana dairy products

Abstract

Genetic traceability is based on the identification of both animals and their products through the study of DNA. With the goal of developing a genetic traceability system for dairy products, the aim of this study was to identify specific microsatellite markers able to discriminate among the most important Sicilian dairy goat breeds, in order to detect possible adulteration in Girgentana dairy products. A total of 20 microsatellite markers were analyzed on a total of 338 individual samples from Girgentana (GIR), Maltese (MAL) and Derivate di Siria (DdS) goat breeds. The first step was to identify breed specific microsatellite markers that can be used for the traceability of dairy products. Analysis of genetic diversity indexes showed that microsatellites panel was highly informative. Presence of private alleles was evidenced in each breed. We focused our attention mainly on alleles present at the same time in MAL and DdS and absent in GIR. Only eight microsatellite markers showed these alleles. To test these eight microsatellites, we first analyzed each of them on pools of DNA of single breed constituted by mixing an increasing number of individuals with known genotypes. From the visual analysis of electropherograms of DNA pools, it was possible to detect that only three of these eight markers (FCB20, SRCRSP5, and TGLA122) showed alleles useful for traceability purpose. In fact, these three microsatellites presented the smaller or the greater allele in MAL and DdS breeds and, therefore, it was not possible to confuse them with “stutter” (fragments smaller/greater than the real allele) when unknown alleles are present within the samples. We analyzed FCB20, SRCRSP5, and TGLA122 markers in DNA samples extracted from cheeses of GIR breed and we obtained very good amplifications. We compared electropherograms with those obtained from DNA pools prepared mixing DNA from GIR, MAL, and DdS in which private alleles of MAL and DdS were visible. From the analysis of electropherograms of DNA extracted from cheeses we did not detect specific alleles of these two breeds. To the best of our knowledge, this work was the first to extend the use of microsatellites for traceability purpose on dairy products. Considering our results, these microsatellite markers could be applied as potential tool in a genetic traceability system of GIR dairy products in order to detect adulteration due to MAL and DdS goat breeds.