MOTLO, J., 2020: Variabilita of IDH1 gene in selected populations of Oriental beech and Common beech. [Bachelor thesis]. Technical Univerzity in Zvolen. Thesis supervisor: Ing. Diana Krajmerová, PhD. Zvolen, 54 p. Genetic structure of population of Oriental and Common beech was studied. For analyses we used 89 samples from 33 populations. We optimised PCR reaction for amplification IDH1 gene in order to produce amplicons suitable for Sanger sequencing. We prepared sequencing reactions and sequenced amplicon in ABI PRISM 3130. Sequences were analysed in program SeqScape where we identified variable sites. SNPs were used as input for program Structure for identification of genetic structure of analysed set of samples. We identified 3 genetic cluster as the most probable number of clusters in the dataset. Populations of Oriental beech and Common beech were clearly differentiated with Bulgarian population being similar to common beech.