Biology subjects

Koutecky, P.

Publications and source records attributed to Koutecky, P..

4 recordsLinked to original sources

bioRxiv2026

Flow cytometry protocols, relative genome size and ploidy levels for 1104 species of non-apomictic angiosperms from the Eastern Alps - a community resource based on the screening of 45,000 samples

Flow cytometry provides a reliable and fast method for estimating genome size and ploidy levels in plants. Until recently, most studies employed fresh tissues, which limits the use of the method with samples from remote areas or when an extremely high number of samples needs to be processed in a short time. Although there is growing evidence that silica-dried material can be used for ploidy estimation in some taxa, no flora-wide study has been available so far. Here, we provide methodological aspects of an unprecedented study exploring ploidy variation of non-apomictic angiosperms in the Eastern Alps. We have analysed ca. 45,000 silica-dried samples of 1135 species using flow cytometry with DAPI as stain. We were able to obtain ploidy level information from 1104 (97%) of species. The unsuccessful species included succulent plants of the family Crassulaceae (genera Jovibarba, Rhodiola, Sedum, Sempervivum), the achlorophyllous parasitic or mycoheterotrophic genera Orobanche and Hypopitis, and a handful of others. About 80% of samples were successfully analysed using a single universal protocol and leaf tissue, while in the remaining species the use of alternative tissues (such as petioles or flowers) and/or protocol modifications were needed (targeting composition of buffers, duration of fixation or staining time or use of alternative buffers). A total of 377 species (34%) included polyploid cytotypes and 179 (16%) species were ploidy-variable. As a community resource, we provide relative genome sizes and ploidy assignments of 1332 cytotypes retrieved from 1104 species along with methodological details (e.g. buffers, standards, analysed plant organs, histogram quality). We believe that this dataset will facilitate future research in particular species as well as in flora-wide investigations of ploidy level variation of the Central European flora in general. We are confident that novel cytotypes of many species will be discovered in other geographic areas, and we would be delighted if the present dataset could serve the botanical community for comparison.

plant biology↗

bioRxiv2024

Polyommatine blue butterflies reveal unexpected integrity of the W sex chromosome amid extensive chromosome fragmentation

Chromosomal rearrangements are crucial in speciation, acting as barriers to gene flow. Holocentric chromosomes, such as those in Lepidoptera, can facilitate karyotype changes. Despite chromosome fusions being more common, speciation events are mostly linked to fissions. Notable karyotypic variation is observed in three clades of the subfamily Polyommatinae (Lycaenidae), with chromosome numbers ranging from n = 10 to n = 225. This study used flow cytometry and molecular cytogenetic analyses to investigate genome sizes and karyotypes in several species of the genera Polyommatus and Lysandra with derived and modal chromosome numbers. The findings show no support for polyploidy, supporting karyotypic diversification via fragmentation of chromosomes. Species with high chromosome numbers have larger genomes, which indicates a potential role of mobile elements but contradicts the hypothesis of holocentric drive. Telomeric signals were detected at the ends of fragmented chromosomes. No interstitial telomeric sequences were detected on autosomes. Interstitial telomeric signals on sex chromosomes, however, revealed multiple sex chromosome systems in Polyommatus dorylas and Polyommatus icarus, with two karyotype races differing in sex chromosome constitution in the latter. Pool-seq and coverage analyses indicated shared fusion of sex chromosomes with an autosome bearing the rDNA locus, followed by a fusion with chromosome 20 in the Czech population. Notably, the W chromosome resists fragmentation, likely due to epigenetic silencing protecting it from activity of mobile elements.

genomics↗

bioRxiv2023

Ghost W chromosomes and unique genome architecture in ghost moths of the family Hepialidae

The classical model of sex chromosome evolution has been recently challenged in moths and butterflies (Lepidoptera). According to the current hypothesis, the adoption of a supernumerary chromosome may have driven the transition from the Z0 to the WZ sex chromosome system in females. However, the evolutionary history of the W chromosome remains enigmatic, especially in the early-diverging lepidopteran lineages. In ghost moths of the family Hepialidae, one of the most basal lepidopteran clades, there is conflicting evidence regarding their sex chromosomes. In this study, we aimed to clarify the status of the hepialid W chromosome. Using cytogenetics and genomics, we investigated the karyotype, sex chromosomes, genome size and repeatome of multiple ghost moth species and reconstructed basic phylogenetic relationships in the group. Our data show that Hepialidae have unusually large genomes (reaching up to 1C = 3 Gb) and are the oldest known lepidopteran clade with a W chromosome. However, the W does not form a typical heterochromatin body in polyploid nuclei, known as sex chromatin, previously employed to detect the presence of W chromosomes across Lepidoptera. Moreover, in some species, the W does not exhibit distinct repeat content and can escape detection via methods that rely on W-specific sequences. Analysis of the Z chromosome confirmed highly conserved gene content, arguing for a possible origin of the hepialid W chromosome from a B chromosome. We hypothesize that the mechanism underlying the formation of sex chromatin could be used in future research to study the origin of the W chromosome.

genomics↗

bioRxiv2017

Peripatric speciation associated with genome expansion and female-biased sex ratios in the moss genus Ceratodon

PREMISE OF THE STUDYA period of allopatry is widely believed to be essential for the evolution of reproductive isolation. However, strict allopatry may be difficult to achieve in some cosmopolitan, spore-dispersed groups, like mosses. Here we examine the genetic and genome size diversity in Mediterranean populations of the moss Ceratodon purpureus s.l. to evaluate the role of allopatry and ploidy change in population divergence.\n\nMETHODSWe sampled populations of the genus Ceratodon from mountainous areas and lowlands of the Mediterranean region, and from western and central Europe. We performed phylogenetic and coalescent analyses on sequences from five nuclear introns and a chloroplast locus to reconstruct their evolutionary history. We also estimated the genome size using flow cytometry, employing propidium iodide, and determined their sex using a sex-linked PCR marker.\n\nKEY RESULTSTwo well differentiated clades were resolved, discriminating two homogeneous groups: the widespread C. purpureus and a local group mostly restricted to the mountains in southern Spain. The latter also possessed a genome size 25% larger than the widespread C. purpureus, and the samples of this group consist entirely of females. We also found hybrids, and some of them had a genome size equivalent to the sum of the C. purpureus and Spanish genome, suggesting that they arose by allopolyploidy.\n\nCONCLUSIONSThese data suggest that a new species of Ceratodon arose via peripatric speciation, potentially involving a genome size change and a strong female-biased sex ratio. The new species has hybridized in the past with C. purpureus.

molecular biology↗