Mountains of the Balkan Peninsula are significant biodiversity hotspots with great species richness and a large proportion of narrow endemics. Processes that have driven the evolution of the rich Balkan mountain flora, however, are still insufficiently explored and understood. Here we focus on a group of Cardamine (Brassicaceae) perennials growing in wet, mainly mountainous habitats. It comprises several Mediterranean endemics, including those restricted to the Balkan Peninsula. We used target enrichment with genome skimming (Hyb-Seq) to infer their phylogenetic relationships, and, along with genomic in situ hybridization (GISH), to resolve the origin of tetraploid Cardamine barbaraeoides endemic to the Southern Pindos Mts. (Greece). We also explored the challenges of phylogenomic analyses of polyploid species and developed a new approach of allele sorting into homeologs that allows identifying subgenomes inherited from different progenitors. We obtained a robust phylogenetic reconstruction for diploids based on 1,168 low-copy nuclear genes, which suggested both allopatric and ecological speciation events. In addition, cases of plastid-nuclear discordance, in agreement with divergent nuclear ribosomal DNA (nrDNA) copy variants in some species, indicated traces of interspecific gene flow. Our results also support biogeographic links between the Balkan and Anatolian-Caucasus regions and illustrate the contribution of the latter region to high Balkan biodiversity. An allopolyploid origin was inferred for C. barbaraeoides, which highlights the role of mountains in the Balkan Peninsula both as refugia and melting pots favoring species contacts and polyploid evolution in response to Pleistocene climate-induced range dynamics. Overall, our study demonstrates the importance of a thorough phylogenomic approach when studying the evolution of recently diverged species complexes affected by reticulation events at both diploid and polyploid levels. We emphasize the significance of retrieving allelic and homeologous variation from nuclear genes, as well as multiple nrDNA copy variants from genome skim data.

• Klíčová slova
• Balkan endemism, Hyb-Seq, Pindhos Mts., allopolyploidy, genomic in situ hybridization, nrDNA, read-backed phasing, target enrichment,
• Publikační typ
• časopisecké články MeSH

Polyploidy is one of the major forces of plant evolution and widespread mixed-ploidy species offer an opportunity to evaluate its significance. We therefore selected the cosmopolitan species Urtica dioica (stinging nettle), examined its cytogeography and pattern of absolute genome size, and assessed correlations with bioclimatic and ecogeographic data (latitude, longitude, elevation). We evaluated variation in ploidy level using an extensive dataset of 7012 samples from 1317 populations covering most of the species' distribution area. The widespread tetraploid cytotype (87%) was strongly prevalent over diploids (13%). A subsequent analysis of absolute genome size proved a uniform Cx-value of core U. dioica (except for U. d. subsp. cypria) whereas other closely related species, namely U. bianorii, U. kioviensis and U. simensis, differed significantly. We detected a positive correlation between relative genome size and longitude and latitude in the complete dataset of European populations and a positive correlation between relative genome size and longitude in a reduced dataset of diploid accessions (the complete dataset of diploids excluding U. d. subsp. kurdistanica). In addition, our data indicate an affinity of most diploids to natural and near-natural habitats and that the tetraploid cytotype and a small part of diploids (population from the Po river basin in northern Italy) tend to inhabit synanthropic sites. To sum up, the pattern of ploidy variation revealed by our study is in many aspects unique to the stinging nettle, being most likely first of all driven by the greater ecological plasticity and invasiveness of the tetraploid cytotype.

• MeSH
• biologická evoluce * MeSH
• délka genomu MeSH
• ekosystém MeSH
• fyziologická adaptace genetika   MeSH
• genom rostlinný * MeSH
• karyotypizace MeSH
• ploidie * MeSH
• selekce (genetika) MeSH
• Urtica dioica klasifikace   genetika   MeSH
• zeměpis MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• západní Asie MeSH

Habitats with alkaline edaphic substrates are often associated with plant speciation and diversification. The tribe Alysseae, in the family Brassicaceae, epitomizes this evolutionary trend. In this lineage, some genera, like Hormathophylla, can serve as a good case for testing the evolutionary framework. This genus is centered in the western Mediterranean. It grows on different substrates, but mostly on alkaline soils. It has been suggested that diversification in many lineages of the tribe Alysseae and in the genus Hormathophylla is linked to a tolerance for high levels of Mg+2 in xeric environments. In this study, we investigated the controversial phylogenetic placement of Hormathophylla in the tribe, the generic limits and the evolutionary relationships between the species using ribosomal and plastid DNA sequences. We also examined the putative association between the evolution of different ploidy levels, trichome morphology and the type of substrates. Our analyses demonstrated the monophyly of the genus Hormathophylla including all previously described species. Nuclear sequences revealed two lineages that differ in basic chromosome numbers (x = 7 and x = 8 or derived 11, 15) and in their trichome morphology. Contrasting results with plastid genes indicates more complex relationships between these two lineages involving recent hybridization processes. We also found an association between chloroplast haplotypes and substrate, especially in populations growing on dolomites. Finally, our dated phylogeny demonstrates that the origin of the genus took place in the mid-Miocene, during the establishment of temporal land bridges between the Tethys and Paratethys seas, with a later diversification during the upper Pliocene.

• MeSH
• alkálie chemie   MeSH
• Bayesova věta MeSH
• Brassicaceae genetika   ultrastruktura   MeSH
• buněčné jádro genetika   MeSH
• časové faktory MeSH
• chromozomy rostlin genetika   MeSH
• druhová specificita MeSH
• fylogeneze * MeSH
• fylogeografie MeSH
• genetická variace MeSH
• haplotypy genetika   MeSH
• hořčík chemie   MeSH
• plastidy genetika   MeSH
• ploidie MeSH
• pravděpodobnostní funkce MeSH
• půda chemie   MeSH
• ribozomy genetika   MeSH
• sekvence nukleotidů MeSH
• trichomy ultrastruktura   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Středomoří MeSH
• Názvy látek
• alkálie MeSH
• hořčík MeSH
• půda MeSH

This article describes the use of cytogenomic and molecular approaches to explore the origin and evolution of Cardamine schulzii, a textbook example of a recent allopolyploid, in its ~110-year history of human-induced hybridization and allopolyploidy in the Swiss Alps. Triploids are typically viewed as bridges between diploids and tetraploids but rarely as parental genomes of high-level hybrids and polyploids. The genome of the triploid semifertile hybrid Cardamine × insueta (2n = 24, RRA) was shown to combine the parental genomes of two diploid (2n = 2x = 16) species, Cardamine amara (AA) and Cardamine rivularis (RR). These parental genomes have remained structurally stable within the triploid genome over the >100 years since its origin. Furthermore, we provide compelling evidence that the alleged recent polyploid C. schulzii is not an autohexaploid derivative of C. × insueta. Instead, at least two hybridization events involving C. × insueta and the hypotetraploid Cardamine pratensis (PPPP, 2n = 4x-2 = 30) have resulted in the origin of the trigenomic hypopentaploid (2n = 5x-2 = 38, PPRRA) and hypohexaploid (2n = 6x-2 = 46, PPPPRA). These data show that the semifertile triploid hybrid can promote a merger of three different genomes and demonstrate how important it is to reexamine the routinely repeated textbook examples using modern techniques.

• MeSH
• biologická evoluce * MeSH
• Cardamine genetika   MeSH
• druhová specificita MeSH
• fylogeneze MeSH
• genom rostlinný genetika   MeSH
• genová dávka MeSH
• hybridizace genetická MeSH
• hybridizace in situ MeSH
• molekulární sekvence - údaje MeSH
• nestabilita genomu * MeSH
• polyploidie MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• triploidie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Flow cytometry (FCM) has been widely used in plant science to determine the amount of nuclear DNA, either in absolute units or in relative terms, as an indicator of ploidy. The requirement for fresh material in some applications, however, limits the value of FCM in field research, including plant biosystematics, ecology and population biology. Dried plant samples have proven to be a suitable alternative in some cases (large-scale ploidy screening) although tissue dehydration is often associated with a decrease in the quality of FCM analysis. The present study tested, using time-scale laboratory and in situ field experiments, the applicability of glycerol-treated nuclear suspension for DNA flow cytometry. We demonstrate that plant nuclei preserved in ice-cold buffer + glycerol solution remain intact for at least a few weeks and provide estimates of nuclear DNA content that are highly comparable and of similar quality to those obtained from fresh tissue. The protocol is compatible with both DAPI and propidium iodide staining, and allows not only the determination of ploidy level but also genome size in absolute units. Despite its higher laboriousness, glycerol-preserved nuclei apparently represent the most reliable way of sample preservation for genome size research. We assume that the protocol will provide a vital alternative to other preservation methods, especially when stringent criteria on the quality of FCM analysis are required.

• MeSH
• buněčné jádro účinky léků   genetika   MeSH
• časové faktory MeSH
• DNA rostlinná analýza   MeSH
• glycerol farmakologie   MeSH
• kryoprotektivní látky farmakologie   MeSH
• ochrana biologická metody   MeSH
• průtoková cytometrie * MeSH
• rostlinné buňky chemie   účinky léků   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH
• glycerol MeSH
• kryoprotektivní látky MeSH

In order to uncover patterns and processes of segregation of co-existing cytotypes, we investigated a zone in the eastern Alps (Austria) where diploid and hexaploid individuals of the alpine herb Senecio carniolicus Willd. (Asteraceae) co-occur. Linking the fine-scale distribution of cytotypes to environmental and spatial factors revealed segregation along an ecological gradient, which was also reflected in the cytotype-associated plant assemblages. Compared to diploids, hexaploids are found in more species-rich and denser communities. This may be due to their better competitive ability and lower tolerance of abiotic stress compared to the diploids. The lack of any intermediate cytotypes suggests the presence of strong reproductive isolation mechanisms, whose nature is, however, elusive.

• Publikační typ
• časopisecké články MeSH