Genetic structure of apple accessions maintained ex situ in Bosnia and Herzegovina examined by microsatellite markers

In order to identify possible mislabeling of the apple accession maintained ex situ in Srebrenik and to gain insight into the genetic structure of the conserved germplasm, 14 accessions from the collection were genotyped using 10 SSR (Simple Sequence Repeats) markers. Obtained SSR profiles were then added to an existing database constructed for previously characterized 24 traditional and 13 international, reference apple cultivars maintained at the same collection. Bayesian analysis implemented in the STRUCTURE program grouped 42 out of 51 analyzed apple accessions (38 traditional and 13 international) into three RPPs (reconstructed panmictic populations) with probability of membership qI higher than 75%. Almost all international, reference cultivars grouped in RPP3, whereas traditional B&H cultivars from the Srebrenik collection grouped in all three RPPs. Large and significant differentiations between all three individual RPPs were detected through the analyses of molecular variance and confirmed with FCA (factorial correspondence analyses). NJ cluster analysis, based on the Bruvo genetic distance, revealed that out of 38 traditional B&H apple cultivars, analyzed in the study, ‘Ljepocvjetka’, ‘Bobovec’ and ‘Bobovec J’ grouped closest to the international reference cultivars. Available date indicates that unlike a large number of B&H apple cultivars which were introduced during the reign of the Ottoman Empire, ‘Ljepocvjetka’ and ‘Bobovec’ were probably introduced at a later date. Cluster analyses also enabled the detection of one synonym and three homonyms within the collection. In four cases, previously conducted identification based on phenotypic analyses was confirmed by genetic analyses. Results of the structure analyses indicate a heterogeneous genetic structure of the analyzed accessions. This characteristic of the B&H apple germplasm could be useful for future breeding programs.