BACKGROUND: Polycomb repressive complexes 1 and 2 play important roles in epigenetic gene regulation by posttranslationally modifying specific histone residues. Polycomb repressive complex 2 is responsible for the trimethylation of lysine 27 on histone H3; Polycomb repressive complex 1 catalyzes the monoubiquitination of histone H2A at lysine 119. Both complexes have been thoroughly studied in Arabidopsis, but the evolution of polycomb group gene families in monocots, particularly those with complex allopolyploid origins, is unknown. RESULTS: Here, we present the in silico identification of the Polycomb repressive complex 1 and 2 (PRC2, PRC1) subunits in allohexaploid bread wheat, the reconstruction of their evolutionary history and a transcriptional analysis over a series of 33 developmental stages. We identified four main subunits of PRC2 [E(z), Su(z), FIE and MSI] and three main subunits of PRC1 (Pc, Psc and Sce) and determined their chromosomal locations. We found that most of the genes coding for subunit proteins are present as paralogs in bread wheat. Using bread wheat RNA-seq data from different tissues and developmental stages throughout plant ontogenesis revealed variable transcriptional activity for individual paralogs. Phylogenetic analysis showed a high level of protein conservation among temperate cereals. CONCLUSIONS: The identification and chromosomal location of the Polycomb repressive complex 1 and 2 core components in bread wheat may enable a deeper understanding of developmental processes, including vernalization, in commonly grown winter wheat.
- MeSH
- chromozomy rostlin MeSH
- fylogeneze MeSH
- mapování chromozomů MeSH
- molekulární evoluce MeSH
- počítačová simulace MeSH
- PRC1 genetika MeSH
- PRC2 genetika MeSH
- pšenice genetika MeSH
- RNA rostlin MeSH
- sekvenování transkriptomu MeSH
- stanovení celkové genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
Suppressed recombination allows divergence between homologous sex chromosomes and the functionality of their genes. Here, we reveal patterns of the earliest stages of sex-chromosome evolution in the diploid dioecious herb Mercurialis annua on the basis of cytological analysis, de novo genome assembly and annotation, genetic mapping, exome resequencing of natural populations, and transcriptome analysis. The genome assembly contained 34,105 expressed genes, of which 10,076 were assigned to linkage groups. Genetic mapping and exome resequencing of individuals across the species range both identified the largest linkage group, LG1, as the sex chromosome. Although the sex chromosomes of M. annua are karyotypically homomorphic, we estimate that about one-third of the Y chromosome, containing 568 transcripts and spanning 22.3 cM in the corresponding female map, has ceased recombining. Nevertheless, we found limited evidence for Y-chromosome degeneration in terms of gene loss and pseudogenization, and most X- and Y-linked genes appear to have diverged in the period subsequent to speciation between M. annua and its sister species M. huetii, which shares the same sex-determining region. Taken together, our results suggest that the M. annua Y chromosome has at least two evolutionary strata: a small old stratum shared with M. huetii, and a more recent larger stratum that is probably unique to M. annua and that stopped recombining ∼1 MYA. Patterns of gene expression within the nonrecombining region are consistent with the idea that sexually antagonistic selection may have played a role in favoring suppressed recombination.
Silene latifolia serves as a model species to study dioecy, the evolution of sex chromosomes, dosage compensation and sex-determination systems in plants. Currently, no protocol for genetic transformation is available for this species, mainly because S. latifolia is considered recalcitrant to in vitro regeneration and infection with Agrobacterium tumefaciens. Using cytokinins and their synthetic derivatives, we markedly improved the efficiency of regeneration. Several agrobacterial strains were tested for their ability to deliver DNA into S. latifolia tissues leading to transient and stable expression of the GUS reporter. The use of Agrobacterium rhizogenes strains resulted in the highest transformation efficiency (up to 4.7% of stable transformants) in hairy root cultures. Phenotypic and genotypic analyses of the T1 generation suggested that the majority of transformation events contain a small number of independent T-DNA insertions and the transgenes are transmitted to the progeny in a Mendelian pattern of inheritance. In short, we report an efficient and reproducible protocol for leaf disc transformation and subsequent plant regeneration in S. latifolia, based on the unique combination of infection with A. rhizogenes and plant regeneration from hairy root cultures using synthetic cytokinins. A protocol for the transient transformation of S.latifolia protoplasts was also developed and applied to demonstrate the possibility of targeted mutagenesis of the sex linked gene SlAP3 by TALENs and CRISPR/Cas9.
- MeSH
- Agrobacterium genetika MeSH
- chromozomy rostlin genetika MeSH
- CRISPR-Cas systémy MeSH
- DNA bakterií genetika MeSH
- exprese genu MeSH
- genetické techniky MeSH
- geneticky modifikované rostliny MeSH
- modely genetické MeSH
- molekulární evoluce MeSH
- regenerace genetika MeSH
- reportérové geny MeSH
- Silene genetika mikrobiologie fyziologie MeSH
- TALENs MeSH
- transformace genetická * MeSH
- Publikační typ
- časopisecké články MeSH
