Evaluation of Turkish apricot germplasm using SSR markers: Genetic diversity assessment and search for Plum pox virus resistance alleles

Abstract

Apricot (Prunus armeniaca L.) is an important fruit crop in Turkey, where a rich diversity of apricot cultivars and seedlings is prevalent. The genetic diversity of the Turkish apricot germplasm was investigated. The profiles of 18 simple sequence repeat (SSR) loci of 239 accessions in the genetic source collection of the country as well as those of European and Pakistani accessions were obtained. Eleven SSRs were selected from the apricot molecular linkage group 1 (LG1), and these are located close to the major Plum pox virus (PPV) resistance locus. The remaining seven SSRs represent the other six linkage groups. A high level of genetic diversity (He=0.74, Ho=0.63) was observed. Stark Early Orange (SEO)/Harlayne-type resistance alleles of three SSR loci (PGS1.21-240, PGS1.23-161 and PGS1.24-119) were found to be rare in the Turkish accessions (1.7%) but were abundantly found in the Pakistani accessions (41.7%). The genetic clustering analyses, the neighbor-joining tree constructed from the genetic distances of the proportions of shared alleles and the population genetic structure did not distinguish the European accessions from the Turkish accessions. However, ‘Harlayne’, ‘SEO’ and the putative resistant apricot accessions were grouped together, indicating a common heritage for the resistant accessions. SSR profiles of the accessions will improve the management of apricot gene banks, and information on the genetic variation in Turkish apricots will assist the international research community.