RESEARCH ARTICLE Perturbation of Parentally Biased Gene Expression during Interspecific Hybridization

Interspecific hybridization often induces epigenetic remodeling that leads to transposon ac-tivation, gene expression changes, and loss of imprinting. These genomic changes can be deleterious and contribute to postzygotic hybrid incompatibility. In Arabidopsis, loss of ge-nomic imprinting of PHERES1 and presumed failure of Polycomb Repressive Complex con-tributes to seed inviability observed in A. thaliana X A. arenosa interspecific hybrids. We used this species pair to further analyze the relationship between parentally biased gene expression and postzygotic hybrid incompatibility using two A. thaliana accessions, Col-0 and C24, with differential seed survival. We found that parentally biased expression was perturbed to a similar degree in both A. thaliana hybrids for PHERES1, HDG3, and six other normally paternally expressed genes. We propose that early genome remodeling and loss of imprinting of seed development genes induces lethality in both compatible and incompatible hybrids