Genetic Diversity and Relatedness of Latvian Pyrus Germplasm assessed by a Set of SSR Markers

Pears (Pyrus communis L.) are not native plant species in Latvia but have a long history of introduction and growing, using various sources of plant material over time. Therefore, the existing collection of genetic resources combines accessions of different origin. To plan the further development of this crop and to ensure its successful preservation, this study aimed to characterise the Latvian Pyrus germplasm collection using SSR molecular markers and to estimate the level of genetic diversity within the pear germplasm collection. Six SSR markers were used to genotype 206 pear accessions of different origin, such as cultivars and hybrids bred in Latvia, landraces collected during expeditions throughout the country, and introduced foreign cultivars. The marker set identified 197 accessions with unique genotypes, and enabled a comparison of different origin groups, and an assessment of genetic diversity. Allele numbers ranged from 15 to 28 for the markers used, whereas observed heterozygosity ranged from 0.519 to 0.956. Grouping of accessions according to geographical origin was not observed. However, the genetic background of Latvian samples was entirely in alignment with international germplasm.