Molecular cytogenetics and flow cytometry reveal conserved genome organization in Pinus mugo and P. uncinata
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The most common representatives of the European mountain pine complex (Pinus mugo s.l.) are P. mugo s.s. and Pinus uncinata.
• Materials and methods
Genome characterization of P. mugo and P. uncinata was studied using fluorescence in situ hybridization of 5S and 18–5.8–26S rDNA, fluorochrome banding for heterochromatin characterization, and flow cytometry for DNA content measurement.
• Results and discussion
Distribution of 5S and 18S rDNA showed identical patterns for both pine species. In contrast, heterochromatin patterns revealed slight differences in the number and position of bands between these two pines. Genome size analysis of 21 P. mugo populations and one P. uncinata population revealed no significant variations across seven European countries. The mean genome size (2C DNA) for the 21 P. mugo populations was 42.56 ± 0.79 pg, equivalent to 41.62 × 103 Mbp, and ranged from 41.08 to 43.95 pg. No relationships were observed between nuclear DNA content and geographic origin of the studied populations.
Our results reveal that the mechanisms shaping molecular cytogenetic organization and genome size did not profoundly differentiate the genomes of P. mugo and P. uncinata. Observed variations in heterochromatin patterns indicate ongoing divergence processes in the genomes of the two pines.
KeywordsGenome Size Chromosome Pair rDNA Locus DAPI Signal Fluorochrome Banding
The authors wish to thank D. Ballian, B. Frajman, P. Schönswetter, J. Vallès, T. Garnatje and B. Heinze for collecting seed material and O. Robin and O. Catrice for technical assistance. The authors are also indebted to the Federal Ministry of Education and Science of Bosnia and Herzegovina (no. 03-39-5980-194-2/08), CNRS (Centre National de la Recherche Scientifique, France) and the NATO project Science for Peace (no. 983838) for their funding of this project. F.B. gratefully acknowledges support from the NORAGRIC (Department of International Environment Studies, Norwegian University of Life Sciences, Aas, Norway). We are very grateful to Dr. Helen McCombie-Boudry for the English revision of manuscript.
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