Variability of the genome size in coniferous plant in extreme environmental conditions

Aim. The features of genome size transformation in conifers growing in extreme environmental conditions are reviewed. Conclusions. Conifers have a very large genome. The main resources of genome size modifications of conifers under extreme environmental conditions are: variability of the chromosome numbers (polyploidy, aneuploidy; mixoploidy), occurrence of B-chromosomes and increasing of its numbers, changes of the content of nuclear DNA, variation of the repetitive DNA sequences (microsatellites, ribosomal RNA genes, transposable elements – retrotransposons), and the chromosomal rearrangements. These features are also components of the epigenetic system which defines the adaptability of the genome changes when exposed to stressful environmental factors. Keywords: Pinophyta, genome, repetitive DNA sequences, epigenetic system.