Genomic imprinting and seed development: endosperm formation with and without sex

During seed development, coordinated developmental programs lead to the for mation of the embryo, endosperm and seed coat. The maternal effects of the genes affected in the fertilisation-independent seed class of mutants play an important role in seed development. The plant Polycomb proteins MEDEA an d FERTILIZATION-INDEPENDENT ENDOSPERM physically interact and form a comple x, in a manner similar to that of their counterparts in animals. Maternal-e ffect phenotypes can result from regulation by genomic imprinting, a phenom enon of critical importance for both sexual and apomictic seed development.