Evaluation of genetic diversity in Pyrus germplasm native to Azad Jammu and Kashmir (Northern Pakistan) revealed by microsatellite markers

Abstract

Pyrus germplasm of Azad Jammu and Kashmir (56 accessions) and East Malling Research Station Kent, UK (8 reference cultivars) were characterized using 12 microsatellite markers assessing genetic diversity. In total, 9 primer pairs revealed 106 putative alleles that ranged from 7 to 19, averaging 11.8 alleles per locus. The size of amplified fragments ranged between 83 and 328 bp, while polymorphism information content varied from 0.780 to 0.918, averaging 0.844. Similarity coefficients ranging from  0.00 to 1.00 was observed in KT53 (Btung) and between BG21 and MZ26 which are both locally called ‘Kotharnul’. UPGMA cluster analysis of similarity  grouped all the genotypes into 3 main clusters, two identical groups and four accession/varieties which fell independently based on their pedigree and geographical origin. Similarity data illustrated an unambiguous genetic diversity and relationship among different ecotypes and varieties in a dendrogram. The most phenotypically variable accessions from different geographical regions fell into two homogeneous groups, ‘A ‘and ‘B’, with some branched accessions. Among reference varieties, 5 distantly fell into one cluster, 2 branched with the lowest affinity to each other and ‘Pendula’ existed independently showing the highest diversity. The local accession KT53 (Btung), representing the highest genetic diversity to all genotypes, had a unique genetic base.

Key words: Genetic diversity, gene pool, simple sequence repeat (SSR), pear.