In animals, Polycomb group (Pc-G) genes mediate the epigenetic control of developmental patterning, ensuring that gene expression patterns established in early development are stably inherited through somatic development. Now Chanvivattana and co-workers report that the Pc-G protein complexes that control flowering in plants are similar to the Polycomb Repressive Complex 2(PRC2) in animals, which functions as a histone methyltransferase (see p. ). The researchers show that the Arabidopsis Pc-G genes EMBRYONIC FLOWER2 (EMF2) and CURLY LEAF (CLF) interact genetically and, importantly, that their protein products physically interact through domains that are conserved in their animal homologues. The CLF-related protein SWINGER and CLF both also interact with two other EMF2-related Pc-G proteins. From these findings, the researchers conclude that PRC2 has been conserved in plants and animals, but that gene duplication and divergence has produced several different flavours of this complex in plants.
