Plant development: Making asymmetric flowers

Flowers are very diverse, with a large range in the size, number, color and morphology of the floral organs, differences that seem to reflect the adaptation of individual species to their mechanism of pollination. The study of the genetic basis of the generation of flower form has been greatly aided by a handful of model plant species, including Antirrhinum (Snapdragon), Arabidopsis and Petunia. These studies have, for instance, identified some of the genes that confer positional information in the floral meristem, such as the flower homeotic genes, mutations in which lead to the conversion of floral organs to types inappropriate for their position in the flower [1]. The sequences of floral organ identity genes and their expression patterns are largely conserved in the flowering plants examined to date, reflecting the nearly universal order of flower organ type: sepals, petals, stamens and carpels, from the outer whorl to the center [1].