Homeotic genes control the development of cell groups — from body segments in the fruitfly Drosophila to floral organs. The cloning of the CURLY LEAF gene in Arabldopsis reveals similar regulation of homeotic genes in this plant as In Drosophila. Flowers and insects may have more in common than meets the eye. Both are composed of repeated units — whorls of floral organs, or body segments — which owe their specific identities to homeotic genes. Although they are unrelated by DNA sequence, the fly and flower genes have essentially the same biological effects: if they are inactivated or expressed ectopically (in the wrong place), normal structures are formed at the wrong positions — legs where antennae should be or petals in place of stamens. These homeotic transformations (making a structure look like some other structure elsewhere in the body) gave the group of developmental control genes their generic name. The similarities between the two systems have now been taken one step further by Goodrich and colleagues, who report on page 44 of this issue that CURLY LEAF, a negative regulator of an Arabidopsis floral homeotic gene, seems to be related to a Polycomb-group repressor of Drosophila homeotic genes.
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