The program of gene expression during development of plants and animals is controlled by epigenetic mechanisms . This control can be accomplished by methylation / demethylation of DNA or methylation / demethylation of specific lysines in histones H3 and H4 . Polycomb group proteins ( PcG ) is responsible for maintaining repressed genes and the group of proteins tritorax ( trxG ) genes maintained in the active state . Methylation of lysine 9 and 27 in histone H3 lysine 20 methylation and histone H4 results in gene silencing .

The phenomenon of genomic imprinting occurs in both animals ( mammals ) and plants ( flowering plants ), and consists of seemingly nierównocennej expression of imprinted genes derived from the father and mother in offspring ; alleles derived from one of the parents are muted. This article presents the Issues of imprintingiem genomowynm associated with plants . In flowering plants the embryo and endosperm are the result of double fertilization, a characteristic only for this group of plants.