The apple (Malus domestica Borkh.) is a fruit tree of the Rosaceae family. It is grown all across the world, and is the third most widely produced fruit crop globally. Although it is a less important crop in Finland economically, its historical, cultural and societal significance is considerable, and it is widely popular in home gardens. At the same time, Finland is the northernmost region where apples can be cultivated, and because of the growing conditions, Finnish apple trees contain valuable genetic variations. In this thesis, we studied Finnish apple germplasm with the aim of compiling a core collection. To perform this task, we studied 704 apple accessions inventoried from southern and central Finland, and Southern Ostrobothnia. The genetic identity of the samples was observed from isolated DNA using 7 microsatellite simple sequence repeat (SSR) markers. The study of the genetic structure showed a rate of variability and diversity comparable to other European apple populations. Based on microsatellite data, we constructed a core collection consisting of 37 entries of Finnish apple trees. Six different methods of core collection construction were tested and compared. Based on a comparison of heterozygosity, allelic diversity and population structure, the core collection compiled with CoreFinder was selected as the best approach. Moreover, guidelines are presented for the implementation of the proposed core collection, with its maintenance and further development in mind.
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