Microsatellite Genotyping and Genetic Diversity of a Greek Pear (Pyrus communis L.) Germplasm Collection

Pear (Pyrus communis L.) is a widely cultivated fruit tree species, valued for its significant economic impact and cultural relevance. The rise in commercial cultivars, characterized by genetic uniformity and high yield, is increasingly displacing traditional landraces. However, traditional varieties are highly adapted to local environmental conditions, having resulted from centuries of selection. In this study, 51 pear (Pyrus communis L.) accessions conserved in the Greek national germplasm collection were genotyped using eight SSR markers recommended by the European Cooperative Programme for Plant Genetic Resources (ECPGR). A total of 44 alleles were detected, including several private alleles, indicative of localized adaptation or potential genetic isolation. Analyses of population structure and genetic diversity, using Principal Coordinate Analysis (PCoA), UPGMA clustering, and Bayesian inference via STRUCTURE, uncovered distinct genetic groupings within the collection. The results revealed moderate genetic variability among the 51 accessions and identified some accessions with significant genetic divergence. These findings underscore the importance of conserving Greek pear germplasm, as it represents an ideal source of desirable traits, such as stress tolerance and fruit quality, which can be utilized in breeding programs.