Genetic variability and population structure of peach accessions from MAS.PES germplasm bank

The aim of the present study was to analyse the genetic diversity and determine the population structure and the phylogenetic relationships of 123 peach accessions from the germplasm bank of the ‘MAS.PES’ breeding programme in order to support future research on breeding activities. Fifteen SSR markers were selected on the basis of a previous study showing a high level of allelic diversity. The population structure was analysed using the software STRUCTURE, adopting the admixture model of ancestry, and the phylogenetic analysis was performed by the DARWIN software, using the neighbour-joining method. The three clusters obtained by analysis of population structure were in accordance with the analysis performed by the software DARWIN. The fifteen studied SSRs amplified 115 alleles, with an average of 7.7 alleles per locus. The most informative markers were BPPCT001, UDP98-412 and EPPCU5176. The observed heterozygosity demonstrates an average of 0.4 alleles per locus, lower than the expected heterozygosity. The fixation index (F) values were positive in all loci, with an average of 0.3 alleles per locus. This result confirms the presence of inbreeding in the evaluated accession, as commonly found in cultivated peach.