The endosperm as a sexual key-lock system is likely the driver of genomic imprinting in Arabidopsis arenosa

Genomic imprinting, an epigenetic phenomenon responsible for parent-of-origin expression, has been well recognized as essential in mammalian development; however, its biological function significance in plants has been more enigmatic. We investigated Arabidopsis arenosa imprinted genes in the endosperm on an unprecedentedly large scale using whole-transcriptome gene regulatory network analysis analyses to bring novel evidence on these questions reveal that they play a central regulatory role in endosperm development. We show that maternally and paternally expressed genes co-occur andbut largely act independently as pleiotropic hub genes in regulatory pathways responsible for processes underlying seed size regulation and resource allocation. Maternally and paternally expressed geneTheir expression profiles are overwhelmingly positively correlated, suggesting likely cooperation. We also reveal novel molecular interactions between imprinted genes interactions, such as where the maternally expressed FIS2 and the paternally expressed GATA29 share target genes. Our work deepens our understanding of the biological significance of imprinted genes in plants and provides compelling evidence for the endosperm as a sexual key-lock system, rather than parental conflict, driving genomic imprinting evolutionary model.