Nejvíce citovaný článek - PubMed ID 19559614
Intrinsic postzygotic isolation typically appears as reduced viability or fertility of interspecific hybrids caused by genetic incompatibilities between diverged parental genomes. Dobzhansky-Muller interactions among individual genes, and chromosomal rearrangements causing problems with chromosome synapsis and recombination in meiosis, have both long been considered as major mechanisms behind intrinsic postzygotic isolation. Recent research has, however, suggested that the genetic basis of intrinsic postzygotic isolation can be more complex and involves, for example, overall divergence of the DNA sequence or epigenetic changes. Here, we review the mechanisms of intrinsic postzygotic isolation from genic, chromosomal, genomic, and epigenetic perspectives across diverse taxa. We provide empirical evidence for these mechanisms, discuss their importance in the speciation process, and highlight questions that remain unanswered.
Hybridization of closely related plant species is frequently connected to endosperm arrest and seed failure, for reasons that remain to be identified. In this study, we investigated the molecular events accompanying seed failure in hybrids of the closely related species pair Capsella rubella and C. grandiflora. Mapping of QTL for the underlying cause of hybrid incompatibility in Capsella identified three QTL that were close to pericentromeric regions. We investigated whether there are specific changes in heterochromatin associated with interspecific hybridizations and found a strong reduction of chromatin condensation in the endosperm, connected with a strong loss of CHG and CHH methylation and random loss of a single chromosome. Consistent with reduced DNA methylation in the hybrid endosperm, we found a disproportionate deregulation of genes located close to pericentromeric regions, suggesting that reduced DNA methylation allows access of transcription factors to targets located in heterochromatic regions. Since the identified QTL were also associated with pericentromeric regions, we propose that relaxation of heterochromatin in response to interspecies hybridization exposes and activates loci leading to hybrid seed failure.
- MeSH
- Capsella klasifikace genetika MeSH
- centromera genetika MeSH
- chromatin genetika metabolismus MeSH
- chromozomální aberace MeSH
- druhová specificita MeSH
- endosperm genetika MeSH
- heterochromatin genetika metabolismus MeSH
- hybridizace genetická * MeSH
- lokus kvantitativního znaku genetika MeSH
- metylace DNA MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny genetika MeSH
- semena rostlinná genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chromatin MeSH
- heterochromatin MeSH
