Genetic Polymorphism of Wild Pear Accessions Collected in Lithuania

Wild pear (Pyrus pyraster (L.) Burgsd.) is pear species growing naturally in Lithuania and is related to cultivated pear (Pyrus communis L.). In some cases, plants identified as P. pyraster represent various stages of hybridization between original P. pyraster and P. communis. Therefore a boundary between cultivated pear, naturalized plants and wild pear is ambiguous. There is limited information on genetic variation and structure of P. pyraster population. The aim of our study was to characterize morphological traits and microsatellite loci of pear originally collected from different localities of Lithuania as naturally growing specimens, presently grown in germplasm collection at the Institute of Horticulture Lithuanian, Research Centre for Agriculture and Forestry (IH LRCAF), and establish capacity of the markers to assess genetic structure of the pear population and suitability for species specific identification. Assessment of thirteen morphological parameters revealed high variation among Pyrus accessions. Morphological differences among the accessions were quantitative rather than qualitative. Characterization of 9 polymorphic microsatellite loci of 84 pear accessions identified 152 polymorphic alleles. The allele number per locus ranged from 12 to 20. The most polymorphic microsatellite loci were EMPc106, EMPc117, NB109a and CHO2c11. High genetic polymorphism was demonstrated by genetic relationship and heterozygosity analysis among accessions. Lower H-o than H-e values indicated possible occurrence of self fertilisation in naturally growing pears. It was shown that morphological variability of Pyrus accessions weakly reflects genetic variation among them. The results of the molecular marker analysis of the accessions of free growing pear collection provided information about genetic background of local pear population that would be useful for restoration and maintaining of genetic diversity of forests.