BACKGROUND: Interspecific hybridisation resulting in polyploidy is one of the major driving forces in plant evolution. Here, we present data from the molecular cytogenetic analysis of three cytotypes of Elytrigia ×mucronata using sequential fluorescence (5S rDNA, 18S rDNA and pSc119.2 probes) and genomic in situ hybridisation (four genomic probes of diploid taxa, i.e., Aegilops, Dasypyrum, Hordeum and Pseudoroegneria). RESULTS: The concurrent presence of Hordeum (descended from E. repens) and Dasypyrum + Aegilops (descended from E. intermedia) chromosome sets in all cytotypes of E. ×mucronata confirmed the assumed hybrid origin of the analysed plants. The following different genomic constitutions were observed for E. ×mucronata. Hexaploid plants exhibited three chromosome sets from Pseudoroegneria and one chromosome set each from Aegilops, Hordeum and Dasypyrum. Heptaploid plants harboured the six chromosome sets of the hexaploid plants and an additional Pseudoroegneria chromosome set. Nonaploid cytotypes differed in their genomic constitutions, reflecting different origins through the fusion of reduced and unreduced gametes. The hybridisation patterns of repetitive sequences (5S rDNA, 18S rDNA, and pSc119.2) in E. ×mucronata varied between and within cytotypes. Chromosome alterations that were not identified in the parental species were found in both heptaploid and some nonaploid plants. CONCLUSIONS: The results confirmed that both homoploid hybridisation and heteroploid hybridisation that lead to the coexistence of four different haplomes within single hybrid genomes occur in Elytrigia allopolyploids. The chromosomal alterations observed in both heptaploid and some nonaploid plants indicated that genome restructuring occurs during and/or after the hybrids arose. Moreover, a specific chromosomal translocation detected in one of the nonaploids indicated that it was not a primary hybrid. Therefore, at least some of the hybrids are fertile. Hybridisation in Triticeae allopolyploids clearly and significantly contributes to genomic diversity. Different combinations of parental haplomes coupled with chromosomal alterations may result in the establishment of unique lineages, thus providing raw material for selection.

• Klíčová slova
• Allopolyploidy, Chromosomal alterations, Elymus repens, FISH, GISH, Higher polyploids, Hybridisation, Thinopyrum intermedium,
• MeSH
• cytogenetické vyšetření MeSH
• DNA rostlinná analýza   MeSH
• genotyp * MeSH
• hybridizace genetická * MeSH
• hybridizace in situ fluorescenční MeSH
• hybridizace in situ MeSH
• lipnicovité genetika   MeSH
• polyploidie * MeSH
• RNA ribozomální 18S analýza   MeSH
• RNA ribozomální 5S analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• DNA rostlinná MeSH
• RNA ribozomální 18S MeSH
• RNA ribozomální 5S MeSH

We examined chromosomal distribution of major ribosomal DNAs (rDNAs), clustered in the nucleolar organizer regions (NORs), in 18 species of moths and butterflies using fluorescence in situ hybridization with a codling moth (Cydia pomonella) 18S rDNA probe. Most species showed one or two rDNA clusters in their haploid karyotype but exceptions with 4-11 clusters also occurred. Our results in a compilation with previous data revealed dynamic evolution of rDNA distribution in Lepidoptera except Noctuoidea, which showed a highly uniform rDNA pattern. In karyotypes with one NOR, interstitial location of rDNA prevailed, whereas two-NOR karyotypes showed mostly terminally located rDNA clusters. A possible origin of the single interstitial NOR by fusion between two NOR-chromosomes with terminal rDNA clusters lacks support in available data. In some species, spreading of rDNA to new, mostly terminal chromosome regions was found. The multiplication of rDNA clusters without alteration of chromosome numbers rules out chromosome fissions as a major mechanism of rDNA expansion. Based on rDNA dynamics in Lepidoptera and considering the role of ordered nuclear architecture in karyotype evolution, we propose ectopic recombination, i.e., homologous recombination between repetitive sequences of non-homologous chromosomes, as a primary motive force in rDNA repatterning.

• MeSH
• chromozomy genetika   MeSH
• DNA genetika   MeSH
• druhová specificita MeSH
• fylogeneze MeSH
• genetická variace MeSH
• genom hmyzu MeSH
• hybridizace in situ fluorescenční MeSH
• karyotypizace MeSH
• molekulární evoluce * MeSH
• motýli genetika   MeSH
• můry genetika   MeSH
• organizátor jadérka genetika   MeSH
• rekombinace genetická MeSH
• repetitivní sekvence nukleových kyselin MeSH
• ribozomální DNA genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA MeSH
• ribozomální DNA MeSH
• RNA ribozomální 18S MeSH