Preliminary evidence of two potentialy native populations of Pinus sylvestris L. in Portugal based on nuclear and chloroplast SSR markers

Pinus sylvestris L. (Scots pine) is one of the most widely distributed conifers across Eurasia. Portugal constitutes its southwestern limit of distribution. Two small populations of P. sylvestris, located at 'Serra do Geres' (NW, Portugal) have been considered potentially native due to their age and evidences provided by multidisciplinary data. Molecular markers, such as nuclear and chloroplast microsatellite markers (nSSR and cpSSR, respectively) could provide additional evidence in order to confirm or refute this hypothesis. In this study, we analyzed the preliminary data obtained with the amplification of five cpSSR loci and four nSSR loci on genomic DNA from a total of 96 individuals belonging to the Portuguese populations of 'Ribeira das Negras' and 'Biduissa' (both from 'Serra do Geres') and compared those data with that achieved in other European native Scots pine populations (from Spain, Germany and Austria). The nSSR loci were highly polymorphic, since we found 16 to 29 alleles per locus. The cpSSRs showed 56 distinct haplotypes and high genetic diversity values (H-g), ranging from 0.668 to 1. Bayesian analysis identified the relevant number of K=3 clusters. The Principal Coordinate Analysis (PCoA) clustered the Portuguese populations apart from each other and, particularly, 'Ribeira das Negras' from all others. Despite the small number of individuals analyzed per population, the pool of these preliminary SSR data reflected different origins of the two Portuguese populations among them and when compared to the Central Europe populations, supporting the hypothesis of existence of native Scots pine populations at 'Serra do Geres' (Portugal).