Cegan, R., Vyskot, B., Kejnovsky, E., Kubat, Z., Blavet, H., Šafář, J., Doležel, J., Blavet, N., Hobza, R.
Background: Genome size evolution is a complex process influenced by polyploidization, satellite DNA accumulation, and
expansion of retroelements. How this process could be affected by different reproductive strategies is still poorly
Methodology/Principal Findings: We analyzed differences in the number and distribution of major repetitive DNA elements
in two closely related species, Silene latifolia and S. vulgaris. Both species are diploid and possess the same chromosome
number (2n = 24), but differ in their genome size and mode of reproduction. The dioecious S. latifolia (1C = 2.70 pg DNA)
possesses sex chromosomes and its genome is 2.56larger than that of the gynodioecious S. vulgaris (1C = 1.13 pg DNA),
which does not possess sex chromosomes. We discovered that the genome of S. latifolia is larger mainly due to the expansion
of Ogre retrotransposons. Surprisingly, the centromeric STAR-C and TR1 tandem repeats were found to be more abundant in S.
vulgaris, the species with the smaller genome. We further examined the distribution of major repetitive sequences in related
species in the Caryophyllaceae family. The results of FISH (fluorescence in situ hybridization) on mitotic chromosomes with the
Retand element indicate that large rearrangements occurred during the evolution of the Caryophyllaceae family.
Conclusions/Significance: Our data demonstrate that the evolution of genome size in the genus Silene is accompanied by
the expansion of different repetitive elements with specific patterns in the dioecious species possessing the sex
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IEB authors: Jaroslav Doležel
, Jan Šafář