RT Journal Article
SR Electronic
T1 Hybrid seed incompatibility in Capsella is connected to chromatin condensation defects in the endosperm
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.09.03.281048
DO 10.1101/2020.09.03.281048
A1 Katarzyna Dziasek
A1 Lauriane Simon
A1 Clément Lafon Placette
A1 Benjamin Laenen
A1 Cecilia Wärdig
A1 Juan Santos-González
A1 Tanja Slotte
A1 Claudia Köhler
YR 2020
UL http://biorxiv.org/content/early/2020/09/03/2020.09.03.281048.abstract
AB 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 QTLs for the underlying cause of hybrid incompatibility in Capsella revealed three QTLs that were close to pericentromeric regions. This prompted us to investigate whether there are specific changes in heterochromatin associated with interspecific hybridizations. Indeed, we found that chromatin was less condensed in the endosperm, while the embryo was not affected. Loss of chromosome condensation was connected with a strong loss of CHG and CHH methylation and mitotic abnormalities. Genome-wide sequencing of hybrid endosperm revealed that the chromosome loss was random and was likely a consequence of reduced chromatin condensation. Consistent with reduced DNA methylation in hybrid endosperm, we found a disproportionate deregulation of genes located close to pericentromeric regions. Among those deregulated genes there were many potential targets of the AGAMOUS-LIKE transcription factor PHERES1, suggesting that reduced DNA methylation allows PHERES1 to hyperactivate its targets. Since the identified QTLs were also associated with pericentromeric regions, we conclude that relaxation of heterochromatin in response to interspecies hybridization exposes and activates loci leading to hybrid seed failure.Competing Interest StatementThe authors have declared no competing interest.