polyploidization
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Hybrid zones provide excellent opportunities to study evolutionary processes linked to interspecific gene flow, including introgression, genetic erosion, polyploid establishment, and speciation. The genus Cardamine (Brassicaceae) serves as an excellent model for polyploid evolution, including one of the few well-documented neo-allopolyploid species that have evolved in the last 300 yr. Using a combination of flow cytometric screening of nuclear DNA content, next-generation restriction site-associated DNA sequencing, and genomic in situ hybridization, we uncovered an unprecedented case of extensive interspecific hybridization in Cardamine, involving four parental species and their predominantly triploid offspring. We demonstrate the recurrent and polytopic origins of both autotriploids and allotriploids, the latter integrating different parental genomes. Our findings highlight Cardamine rivularis as a central player in this system, likely producing unreduced female gametes at a high rate, which drives the formation of diverse triploids. However, this species may also face the risk of genetic swamping and ecological displacement. The substantial genetic variation of the hybrids, their high frequency, partial fertility, and efficient clonal spread suggest significant evolutionary potential. Overall, we propose that these hybrid zones provide a rare and valuable natural laboratory for studying the emergence of neo-allopolyploids and the mechanisms shaping polyploid evolution.
- Klíčová slova
- Cardamine, RAD sequencing, allopolyploidy, hybrid zone, neopolyploids, triploids,
- Publikační typ
- časopisecké články MeSH
Chromosomal rearrangements act as barriers to gene flow and can thus promote speciation. In moths and butterflies (Lepidoptera), which possess holocentric chromosomes facilitating karyotype changes, chromosome fusions are more common than fissions. Yet, limited evidence suggests that when speciation involves chromosomal rearrangements, it is most often linked to fissions. Notable karyotypic variation is observed in three clades of the subfamily Polyommatinae (Lycaenidae), with chromosome numbers ranging from n = 10 to 225. We investigated genome sizes and karyotypes in several species of the genera Polyommatus and Lysandra with modal and derived high chromosome numbers. Our findings showed no support for polyploidy, confirming previous conclusions about karyotypic diversification via chromosome fragmentation in this butterfly family. Species with high chromosome numbers have slightly larger genomes, which indicate a potential role of repetitive sequences but contradict the hypothesis of holocentric drive. Ends of fragmented chromosomes were healed with telomeres synthesized de novo, which were significantly larger than those of species with modal karyotype. No interstitial telomeric sequences were detected on autosomes. Internal telomeric signals on sex chromosomes, however, revealed multiple sex chromosome systems in Polyommatus (Plebicula) dorylas and Polyommatus icarus, with two karyotype races differing in sex chromosome constitution in the latter. Notably, the W chromosome resisted fragmentation, presumably due to its epigenetic silencing.
- Klíčová slova
- Polyommatus, butterfly, fission, fusion, sex chromosomes, telomere,
- MeSH
- chromozomy hmyzu MeSH
- karyotyp MeSH
- motýli * genetika MeSH
- pohlavní chromozomy * genetika MeSH
- polyploidie MeSH
- telomery * genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Polyploidy and subsequent post-polyploid diploidization (PPD) are key drivers of plant genome evolution, yet their contributions to evolutionary success remain debated. Here, we analyze the Malvaceae family as an exemplary system for elucidating the evolutionary role of polyploidy and PPD in angiosperms, leveraging 11 high-quality chromosome-scale genomes from all nine subfamilies, including newly sequenced, near telomere-to-telomere assemblies from four of these subfamilies. Our findings reveal a complex reticulate paleoallopolyploidy history early in the diversification of the Malvadendrina clade, characterized by multiple rounds of species radiation punctuated by ancient allotetraploidization (Mal-β) and allodecaploidization (Mal-α) events around the Cretaceous-Paleogene (K-Pg) boundary. We further reconstruct the evolutionary dynamics of PPD and find a strong correlation between dysploidy rate and taxonomic richness of the paleopolyploid subfamilies (R2 ≥ 0.90, P < 1e-4), supporting the "polyploidy for survival and PPD for success" hypothesis. Overall, our study provides a comprehensive reconstruction of the evolutionary history of the Malvaceae and underscores the crucial role of polyploidy-dysploidy waves in shaping plant biodiversity.
Plants rely on tight coordination between nuclear, mitochondrial, and chloroplast genomes to form essential multi-enzyme cytonuclear complexes. Whole-genome duplication (WGD) doubles the nuclear genome, potentially disrupting cytonuclear stoichiometry unless organellar genomes respond accordingly. Targeted analyses of chloroplasts and mitochondria enabled us to dissect the extent and mechanisms of adjustments in both organelles immediately after WGD and across generations in Arabidopsis auto- and allopolyploids. We observed a substantial overcompensation of organellar genome copies in both organelles in early-generation autotetraploids primarily through multiplication of DNA copies within organelles rather than increasing the number of organelles. Despite higher DNA content, mitochondria maintained their volume, and chloroplasts were even smaller. In successive generations, chloroplast DNA copy numbers continued to rise, whereas mitochondrial DNA copies declined. Gene expression patterns also differed between chloroplasts and mitochondria and between auto- and allopolyploids. In autopolyploids, immediate transcriptional changes were minimal, but by the fourth generation after WGD, nuclear genes involved in mitochondria-nuclear complexes were downregulated. In allopolyploids, transcriptional changes appeared immediately in the first generation (chloroplast genes were upregulated and mitochondrial genes were downregulated). Our findings demonstrate that cytonuclear balance is restored through dynamic, organelle-specific, and polyploid-type-specific mechanisms. These insights advance our understanding of the evolution of polyploid genomes.
- Klíčová slova
- chloroplasts, cytonuclear interactions, gene expression, interspecific hybridization, mitochondria, organellar DNA, stoichiometry, whole genome duplication,
- MeSH
- Arabidopsis * genetika MeSH
- buněčné jádro * genetika MeSH
- chloroplasty genetika MeSH
- DNA chloroplastová genetika MeSH
- genom chloroplastový genetika MeSH
- genom rostlinný genetika MeSH
- mitochondriální DNA genetika MeSH
- mitochondrie genetika metabolismus MeSH
- polyploidie * MeSH
- regulace genové exprese u rostlin MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA chloroplastová MeSH
- mitochondriální DNA MeSH
Abundance of established polyploid lineages varies across lineages, evolutionary time, and geography, suggesting both genetics and environment play a role in polyploid persistence. We show Arabidopsis lyrata is the most polyploid-rich species complex in the Arabidopsis genus, with multiple origins of autotetraploidy. This is revealed by genomic data from over 400 A. lyrata samples across Eurasia. We found over 30 previously undescribed autotetraploid populations in Siberia with a minimum of two separate origins, independent of those previously reported in Central Europe. The establishment of Siberian tetraploids is mediated by meiotic adaptation at the same genes as in European tetraploid A. lyrata and Arabidopsis arenosa, despite their genomic divergence and geographical separation. Haplotype analysis based on synthetic long-read assemblies supports the long-range introgression of adaptive alleles from the tetraploid interspecific pool of European A. lyrata and A. arenosa to tetraploid Siberian A. lyrata. Once adaptations to polyploidy emerge, they promote the establishment of new polyploid lineages through adaptive inter- and intraspecific introgression.
- Klíčová slova
- Arabidopsis lyrata, adaptation, introgression, polyploid,
- MeSH
- Arabidopsis * genetika MeSH
- genom rostlinný MeSH
- genová introgrese * MeSH
- haplotypy MeSH
- polyploidie * MeSH
- tetraploidie MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
The reorientation of Callisia fragrans (Lindl.) Woodson, from therapeutic to ornamental use, exemplifies a broader domestication trend, favoring aesthetics over medicinal properties. Renewed phytomedicinal interest and the rise of plant extract markets drive demand for organic, sustainable consumer products, heightening the competition for superior cultivars. Synthetic polyploidization using oryzalin was conducted to obtain high-quality cultivars of C. fragrans, facilitating enhanced phenotypic and biological traits without genetic modification. This study aimed to explore the metabolic spectrum and biological activities of oryzalin-induced polyploid C. fragrans for its advanced medicinal application. Flow cytometric analysis confirmed the ploidy level of the plants. Consequently, GC-FID and 1H NMR analyses revealed distinct metabolite profiles, with increased ethyl stearate, malic acid, gallic acid, fumaric acid, and unique compounds like (Z)-11-eicosenoic acid and dodecan-1-ol in polyploids. Polyploid extracts demonstrated exceptional antioxidant capacity, with DPPH, ORAC, and ABTS assays showing higher radical scavenging and oxygen absorbance abilities than diploid extracts. The polyploid extract showed enhanced antimicrobial activity against skin pathogens, including Methicillin-resistant Staphylococcus aureus (MRSA). Callisia extracts, meticulously at a low concentration of 25 µg/mL, showed cytoprotective effects on HT-29 cells, mitigating H₂O₂-induced oxidative stress. Furthermore, treatment with polyploid extract was associated with the downregulation of the expression of pro-inflammatory enzymes COX-1 and COX-2, suggesting a potentially greater anti-inflammatory effect compared to the diploid extract. These findings depict enhanced metabolite accumulation and biological activities in polyploid compared than diploid progenitor, highlighting the potential of the novel polyploid C. fragrans variety for future therapeutic applications, particularly in pharmaceutical and cosmetic industries.
- Klíčová slova
- Anti-inflammatory activity, Antioxidant activity, GC-FID, NMR, Polyploidization, Skin infection,
- MeSH
- antioxidancia farmakologie metabolismus MeSH
- cyklooxygenasa 1 metabolismus MeSH
- cyklooxygenasa 2 metabolismus genetika MeSH
- genotyp MeSH
- lidé MeSH
- polyploidie * MeSH
- rostlinné extrakty * farmakologie chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antioxidancia MeSH
- cyklooxygenasa 1 MeSH
- cyklooxygenasa 2 MeSH
- rostlinné extrakty * MeSH
Sexual reproduction relies on meiotic chromosome pairing to form bivalents, a process that is complicated in polyploids owing to the presence of multiple subgenomes1. Uneven ploidy mostly results in sterility due to unbalanced chromosome pairing and segregation during meiosis. However, pentaploid dogroses (Rosa sect. Caninae; 2n = 5x = 35) achieve stable sexual reproduction through a unique mechanism: 14 chromosomes form bivalents and are transmitted biparentally, while the remaining 21 chromosomes are maternally inherited as univalents2,3. Despite being studied for over a century, the role of centromeres in this process has remained unclear. Here we analyse haplotype-resolved chromosome-level genome assemblies for three pentaploid dogroses. Subgenome phasing revealed a bivalent-forming subgenome with two highly homozygous chromosome sets and three divergent subgenomes lacking homologous partners, therefore explaining their meiotic behaviour. Comparative analyses of chromosome synteny, phylogenetic relationships and centromere composition indicate that the subgenomes originated from two divergent clades of the genus Rosa. Pollen genome analysis shows that subgenomes from different evolutionary origins form bivalents, supporting multiple origins of dogroses and highlighting variation in subgenome contributions. We reveal that bivalent-forming centromeres are enriched with ATHILA retrotransposons, contrasting with larger tandem-repeat-based centromeres mainly found in univalents. This centromere structural bimodality possibly contributes to univalent drive during female meiosis. Our findings provide insights into the unique reproductive strategies of dogroses, advancing our understanding of genome evolution, centromere diversity and meiotic mechanisms in organisms with asymmetrical inheritance systems.
- MeSH
- centromera * genetika metabolismus MeSH
- chromozomy rostlin genetika MeSH
- fylogeneze MeSH
- genom rostlinný genetika MeSH
- haplotypy genetika MeSH
- meióza * genetika MeSH
- polyploidie * MeSH
- pyl genetika cytologie MeSH
- retroelementy genetika MeSH
- syntenie genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- retroelementy MeSH
Polyploidization (whole-genome duplication, WGD) is a widespread large-effect macromutation with far-reaching genomic, phenotypic, and evolutionary consequences. Yet, we do not know whether the consistent phenotypic changes that are associated with polyploidization translate into predictable changes in ecological preferences. Niche modeling studies in mixed-ploidy species provide an opportunity to compare recently originated polyploids with their lower-ploidy ancestors. However, the available isolated studies provide contrasting results and the diverse methodologies used limit generalization. Based on 25,857 georeferenced ploidy-verified occurrence data for 129 mixed-ploidy flowering plant species, we tested in a unified statistical framework whether WGD is associated with consistent changes in climatic niche and in past, current, and predicted future range size. We found that 74% of species exhibited significant niche shifts associated with ploidy transition. However, there was no consistent environmental parameter underlying ploidy differentiation across species, nor was there consistent support for polyploid range or niche expansion in a subset of 75 densely sampled species with sufficient data for modeling. Our results demonstrate that polyploidization is an important factor affecting niche evolution of a species, but the environmental parameters underlying the ploidy-related niche shifts vary from species to species, demonstrating limited predictability of the outcomes of WGD in ecological space.
- Klíčová slova
- ecological differentiation, environmental niche modelling, meta-analysis, niche evolution, polyploidy,
- MeSH
- biologická evoluce MeSH
- duplikace genu * MeSH
- ekosystém * MeSH
- genom rostlinný * MeSH
- Magnoliopsida * genetika MeSH
- ploidie MeSH
- podnebí * MeSH
- polyploidie * MeSH
- Publikační typ
- časopisecké články MeSH
The triploid block, primarily caused by endosperm developmental issues, is known as a significant barrier to interploidy hybridization among flowering plants and, thereby, polyploid speciation. However, its strength varies across taxa, with some instances of leakiness, questioning its universal role as a barrier. We conducted a literature survey to explore the causes of the variation in the strength of the triploid block across 11 angiosperm families. We assessed the impact of interploidy cross direction, types of endosperm development, endosperm persistence at seed maturity, and divergence between cytotypes using a Bayesian meta-analysis. We found a significant influence of the type of endosperm in shaping variation in triploid block strength. Other factors tested had no impact on triploid seed viability, probably due to limited data and inconsistencies in estimation methods across the literature. In addition, triploid seed viability in experimental crosses was sometimes correlated to the occurrence of triploid hybrids in nature, sometimes not, suggesting a mixed role for the triploid block in shaping interspecies gene flow. Altogether, our study highlights the need for unified approaches in future studies on the triploid block to advance our understanding of its variation and evolutionary implications.
- Klíčová slova
- Endosperm development, hybrid seed lethality, interploidy gene flow, natural variation, polyploidy speciation, triploid block,
- MeSH
- biologická evoluce * MeSH
- endosperm genetika růst a vývoj MeSH
- hybridizace genetická MeSH
- Magnoliopsida * genetika MeSH
- polyploidie * MeSH
- semena rostlinná genetika MeSH
- tok genů MeSH
- triploidie * MeSH
- vznik druhů (genetika) * MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- přehledy MeSH
Aquatic plants are generally attributed to have larger ranges than their terrestrial counterparts, but this knowledge is often hindered by insufficient exploration of their diversity. To fill this gap, we investigated the taxonomically extremely challenging aquatic plant group Ranunculus sect. Batrachium in south-western Europe, which is an important glacial refugium, using flow cytometry, chromosome counting and DNA sequencing (ITS nuclear region and two non-coding plastid regions). In a dataset comprising 587 individuals from 117 localities, we detected 36 cytotypes across seven ploidy levels, which included a considerable proportion of previously unrecognized diversity consisting of three high ploidies (7x, 10x, 12x), seven cryptic species, two additional unclassifiable biotypes and nine hybrids. Two thirds of the taxa are polyploid, with many species presumed to be of allopolyploid origin. We discovered a remarkably close relationship between the local cytotype of R. peltatus s.l. and the morphologically distinct, widespread and ecologically specialized species R. fluitans; the latter might have evolved as a result of rapid adaptation to newly colonized river habitats in the early postglacial period. Undeniably, diversity within this group is still incompletely understood and is far more complex than current taxonomic concepts suggest.
- Klíčová slova
- Chromosome number, Cryptic variation, Genome size, Hybridization, Molecular identification, Polyploidy,
- MeSH
- biodiverzita * MeSH
- biologická evoluce * MeSH
- DNA rostlinná genetika MeSH
- fylogeneze MeSH
- genetická variace MeSH
- molekulární evoluce MeSH
- ploidie MeSH
- polyploidie MeSH
- Ranunculus * genetika klasifikace MeSH
- sekvenční analýza DNA MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
- Názvy látek
- DNA rostlinná MeSH
