Sequencing of the camelina (Camelina sativa) genome revealed that the genome consists of three parental subgenomes. However, how the hexaploid camelina genome originated and how the three subgenomes are related to other genomes in the genus Camelina remained unknown. We tackled these questions by using comparative chromosome painting, genomic in situ hybridization, and multi-gene phylogenetic analyses. We wanted to find the most probable parental genomes of the hexaploid camelina and moreover to understand how its genome is related to genomes of other Camelina species.
Genomes of diploid camelinas (C. hispida, n = 7 chromosomes; C. laxa, n = 6; and C. neglecta, n = 6) originated from an ancestral n = 7 genome. The allotetraploid C. rumelica genome (n = 13, N6H genome) arose from hybridization between diploids C. neglecta (n = 6, N6) and C. hispida (n = 7, H), and the N subgenome has been substantially reshuffled by chromosomal rearrangements. The allohexaploid genomes of C. sativa (n = 20, N6N7H) originated through hybridization between an extinct autotetraploid C. neglecta-like genome (n = 13, N6N7) and C. hispida (n = 7, H), and the three subgenomes remained overall stable since the genome merger. Remarkably, the ancestral and diploid Camelina genomes were shaped by complex chromosome shattering, resembling similar events associated with human disorders.
The Camelina story was published in Plant Cell!
Mike Chester (Royal Botanic Gardens, Kew) posted a comment on our paper published in Annals of Botany earlier this year (Mandáková T, Zozomová-Lihová J, Kudoh H, Zhao Y, Lysak MA, Marhold K, The story of promiscuous crucifers: origin and genome evolution of an invasive species, <i>Cardamine occulta</i> (Brassicaceae), and its relatives.)
Martin and Hanna Schneeweiss (University of Vienna) are guest editors of a research topic in Frontiers in Plant Science entitled Chromosomal Evolution in Plants.
About this Research Topic
Plant karyotypes display a great diversity in chromosome number and morphology, as well as DNA amount and composition. Chromosomal evolution, one of the driving forces underlaying diversification and speciation in plants, is usually complex and employs various mechanisms. Although chromosome number and karyotype structure are still the most frequently recorded cytological characters, last decades have brought a range of new tools that allow for better insights into chromosomal and genome evolution in plants. The massively parallel sequencing technology (next-generation sequencing, NGS) has in last few years revolutionized nearly all biological disciplines. Genome skimming using NGS and whole-genome sequences opened up new horizons for modern evolutionary cytogenetics, or more accurately, cytogenomics. It therefore became obvious that plant evolutionary cytogenomics can benefit from whole-genome sequences, and comparative plant genomics can be associated to physical localization of DNA sequences on chromosomes, improving whole-genome and chromosome-level assemblies. Thus, we are now able to take full advantage of the modern approaches to finally tackle the long-standing questions in chromosome biology and genome evolution in any plant species group.
This Research Topic aims to bring together a collection of articles addressing important questions related to genome and chromosomal evolution across the green plant phylogeny including flowering plants, gymnosperms, ferns, bryophytes and algae. Studies presenting novel and exciting data on genome and chromosomal evolution, as well as new methodological tools, are welcome. The goal is to advance our understanding of plant karyotype evolution and its contribution to diversification and speciation, and allow for exchange of data, ideas, and hypotheses obtained making full advantage of new methodological approaches.
Specifically, we encourage submission of Original Research, Reviews, Mini Reviews, Methods, Perspectives, and Opinions covering the following topics:
- Reconstructing pathways of karyotype and genome evolution
- Paleogenomics and paleogenomes
- Polyploidy and post-polyploid genome diploidization
- Dysploid chromosomal changes
- Structure of plant chromosomes
- Impact of interphase chromosomes organization on genome evolution
- Repeatome and genome size evolution
- The role of chromosomal rearrangements in plant speciation
Keywords: Plant Karyotype, Plant Genome Evolution, Cytogenetics, Cytogenomics, Chromosomal Evolution
In a study published in Plant Physiology, we showed that the tetraploid horseradish and watercress genomes are almost identical structurally (differentiated only by a 2.4-Mb chromosome translocation), and that presumably both originated by autopolyploidization. Both genomes closely resemble bittercress (Cardamine) genomes from the same tribe. This analysis represents a first stepping stone for the future whole-genome sequencing efforts and genetic improvement of both crop species. The paper was highlighted on CEITEC's home page: https://www.ceitec.eu/scientists-have-mapped-the-horseradish-and-watercress-genome/t10039.
The ancestral Ricotia genome was formed by a rare inter-clade hybridization event, followed by cladogenesis accompanied by three decreases in chromosome number (descending dysploidies). The last dysploidy was mediated by a unique chromosomal rearrangement, proving that structurally identical or similar fusion chromosomes may be formed in land plants from the same precursor chromosomes by different translocation mechanisms repeatedly after several million years.
Teri was award for extraordinary research results achieved by scientists in the age group under 35 from the Rector of Masaryk University. Congratulations!
Post-polyploid diploidization and diversification through dysploid changes
Our review on the role of chromosomal rearrangements and descending dysploidies in post-polyploid diploidization in plants was published as a part of the special issue Genome studies and molecular genetics 2018 of Current Opin Plant Biol (https://www.sciencedirect.com/journal/current-opinion-in-plant-biology/v...)!
These results are among the first to demonstrate multispeed genome evolution in taxa descending from a common allopolyploid ancestor. Clade-specific post-polyploid diploidization can operate at different rates and efficacies and can be tentatively linked to life histories and the extent of taxonomic diversity.
Our paper on mesopolyploid whole-genome duplications selected as a Featured Article in Plant Journal
Our paper reporting on concealed whole-genome duplications in several Brassicaceae tribes and genera was selected as a Featured Article by the editors of Plant Journal and advertised by the cover illustrating the mesohexaploid origin of the South African tribe Heliophileae (c. 100 species).
We were awarded an Inter-Excellence grant to work on tribe Boechereae
We were successful with our application for a three-year Inter-Excellence research grant to work on genome evolution of tribe Boechereae, endemic to North America. This is a joint project with the laboratory of prof. Tom Mitchell-Olds at the Duke University.
A chromosome inversion affects multiple ecologically important traits in Boechera
What is the role of inversions in adaptation and speciation? New data on the adaptive role of a young paracentric inversion were gained in the study led by Tom Mitchell-Olds (Duke University) and published in the April issue of Nature Ecology and Evolution. This paper is a follow-up of our Boechera study published in Plant Journal 82, 785-793 (2015).
Teri gave an invited lecture on "Multiple patterns of genome evolution in the Brassicaceae: a lesson from the polyploid-rich genus Cardamine" at the International Conference on Polyploidy, Hybridization and Biodiversity in Rovinj, Croatia.
Ancestral building blocks of crucifer genomes revisited
We revisited the concept of the Ancestral Crucifer Karyotype (ACK) and the definition of a revised set of 22 conserved genomic blocks across the Brassicaceae family including Arabidopsis and crop Brassicas. We reviewed how the ACK has been utilized for the analysis of a remarkable thirty-five crucifer genomes during the last 10 years. This work was published in Current Opinion in Plant Biology.
Basic features of the chromDraw tool are described in our recent paper published in Chromosome Research.
Plant Cytogenomics in Brno, Czech Republic: Treading in Mendel’s Genomic Footsteps
In the September issue of Plant Physiology, we describe the comparative genome structure of the Alpine Pennycress (Noccaea or Thlaspi caerulescens) and its evolution from an ancestral genome. We show that genome evolution in this important model species involved an unusually high number of pericentric inversions, which could have facilitated the evolution of enhanced metal homeostasis gene expression, a known hallmark of metal hyperaccumulation.
A Spotlight article written by Marcus Koch (University of Heidelberg) can be downloaded from the link below.
BRASSICACEAE @ Botany 2015 - Edmonton, Alberta - July 25 - 29, 2015
A colloquium on recent advances in phylogenetics, systematics and genome evolution of Brassicaceae will bring together leading experts in the field. Among our speakers are Ihsan Al-Shehbaz, Ivalu Cacho, Hong Ma, Karol Marhold, Marcus Koch, and Eric Schranz.
Organizers: K. Marhold and M. A. Lysak
Mandáková et al. (2015) Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes. Plant Journal 82: 785–793.
Willing et al. Genome expansion of Arabis alpina linked with retrotransposition and reduced symmetric DNA methylation. Nature Plants (doi:10.1038/nplants.2014.23)
An international team led by Georg Coupland and Korbinian Schneeberger (MPI for Plant Breeding Research, Cologne) published a de novo assembly for the 375 Mb genome of A. alpina. This paper also reports on the structure and evolution of the eight chromosomes of this important perennial model plant. The A. alpina genome is the first sequenced genome from the largest tribe of Brassicaceae (the Arabideae contain c. 487 species in 17 genera).
Genome evolution and spatiotemporal diversity in the tribe Arabideae
We were recently awarded a three-year project from the Czech Science Foundation to investigate karyotype and genome evolution in the Arabideae.
The tribe Arabideae is the largest Brassicaceae tribe with >487 species; many Arabis and Draba species being wide-spread and some cultivated as ornamental plants. Arabideae diversified into several clades with contrasting phylogeographic history represents a superb system to analyze plant genome evolution. We aim to describe and reconstruct patterns of genome reorganization and repeat evolution by comparative cytogenomic and epigenetic methods, and by next-generation sequencing. 01/2015 - 12/2017.
Investigating genomes of Icelandic crucifer species
The EEA project aims to elucidate genome structure and evolution in selected Icelandic crucifer genera (e.g., Cardamine, Draba and Subularia).
A joint project between the Lysak lab and the group of prof. Kesara Anamthawat-Jónsson (Unversity of Iceland). 04/2015 - 05/2016.
More information about the project can be found here.
Terminal and interstitial telomeric repeats
Majerova E., Mandáková T., Vu G.T.H., Fajkus J., Lysak M.A., Fojtova M. 2014. Epigenetic character of telomeric chromatin in model plants with distinct localization of telomeric repeats. Frontiers in Plant Science 5:593. [PDF]