Development of microsatellite multiplex PCRs for gilthead seabream ( Sparus aurata L.)

Gilthead seabream (Sparus aurata L.) is one of the most important species in the Mediterranean aquaculture. The industry has optimized their productions through mainly management factors such as nutrition, reproduction or prevention of disease, but not by genetic improvement. This is due in part to that the reconstruct the genealogy of fish represents a high cost for companies. This is because culture of this species is generally performed through mass spawning where parent–offspring relationships are unknown, so the introduction of breeding programmes in this kind of industrial production system requires physical tagging to identify all individuals in conjunction with DNA analysis to parental assignments. In the present study, two new microsatellites multiplex PCRs for gilthead seabream were developed from redesigned primers in order to maximize the number of markers per reaction. The evaluation and validation of these multiplexes (Multiplex A and Multiplex B) were carried out upon 78 individuals from four different populations of gilthead seabream, one of them was a family in order to confirm the correct inheritance and allelic segregation of each locusFrom 24 redesigned specific markers described in the genetic map of this species (Franch, et al., 2006; Senger, et al., 2006), the number of markers included in the final multiplex PCRs were ten in each reaction. All markers showed high levels of polymorphism and heterozygosity, indicating the existence of genetic variability. The probabilities of exclusion (PE) for each marker were also high. The a priori combined parental exclusion probability for both multiplex was maximum (0.999). Polymorphic Information Content (PIC) values for the markers included in both multiplex have been estimated for the first time. Most of markers were moderately informative and the mean values were high, 0.6034 (multiplex A) and 0.6491 (multiplex B). These robust multiplex PCRs will be a fundamental genotyping tool for parental assignments without interfering with the production system and with a low cost. At the same time, they could also be used in search and identification of QTL