The paternally derived genome opposes seed dormancy induction by the mother plant in Arabidopsis

Seed dormancy in Arabidopsis is known to be mediated by the interaction of maternal and zygotic genomes during seed maturation. While studies have revealed the extensive influence of maternal processes on dormancy and germination, less is known about the influence of the father. Here we exploit differences in ploidy to explore the role of the paternal genome on progeny seed dormancy. We show that paternal genome acts to reduce seed dormancy regardless of maternal genome dose, resulting in lower dormancy in tetraploid Arabidopsis versus genetically identical diploids. We show that this paternal effect requires synthesis of RNA Polymerase IV-dependent RNAs in the male gametophyte which oppose the dormancy-inducing effects of maternal siRNAs on seed coat and endosperm development. We conclude that the paternal genome has evolved to subvert the dormancy-inducing role of the mother plant in progeny seeds.