Naslov
Molecular-cytogenetic studies of ribosomal RNA genes and heterochromatin in three European Fraxinus species

Autori
Siljak-Yakovlev, Sonja ; Temunović, Martina ; Robin, Odile ; Raquin, Christian ; Frascaria-Lacoste, Nathalie

Izvornik
Tree genetics & genomes (1614-2942) 10 (2014), 2; 231-239

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
fluorochrome banding; fluorescence in situ hybridization (FISH); Fraxinus; GC-rich DNA; genome size; heterochromatin and rDNA physical mapping

Sažetak
Three European representatives of the genus Fraxinus were studied for the first time for their rDNA and heterochromatin patterns. The physical mapping of two rRNA gene families 5S and 18S-5.8S-26S (45S) and the distributional pattern of GC-rich regions in the chromosomes have been established by means of fluorescence in situ hybridization (FISH) and fluorochrome banding with chromomycin A3. The genome size was assessed by flow cytometry. Heterochromatin and rDNA organization was conserved and almost identical for two species from Fraxinus section (Fraxinus angustifolia and F. excelsior). The number and position of rDNA loci in Fraxinus ornus (section Ornus) were similar, however the organization of genes was quite different. In this species the 5S and 45S rRNA genes were colocalized at the level of satellites of two chromosome pairs bearing nucleolar organizing region (NORs) and at the proximal side of secondary constrictions of one of these chromosome pairs. In F. angustifolia and F. excelsior only 45S were situated at the level of satellites and secondary constrictions, while the 5S was located just under 45S in distal part of short arm of one of two marked pairs. The number and position of GC-rich DNA correspond to those of 45S loci. The genome size was of 1.54 and 1.68 pg for F. angustifolia and F. excelsior, respectively. Fraxinus ornus possessed the highest 2C DNA value (1.98 pg). In the light of these cytogenetic features the clear differentiation between two sections (Fraxinus and Ornus) was observed both at the rDNA and genome size level.

Izvorni jezik
Engleski

Znanstvena područja
Biologija, Šumarstvo

POVEZANOST RADA