Hybrid seed incompatibility in < i > Capsella < /i > is connected to chromatin condensation defects in the endosperm

In this study, we investigated the molecular events accompanying seed failure in hybrids of the closely related species pairCapsella rubella andC.grandiflora. Mapping of QTL for the underlying cause of hybrid incompatibility inCapsella 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.

Source: PLoS Genetics - February 11, 2021 Category: Genetics & Stem Cells Authors: Katarzyna Dziasek Source Type: research