The ABCs of Floral Homeotic Genes Review

Homeotic mutants, that is, mutants with a normal organ in a place where an organ of another type is typically found, were first recognized in plants. The earliest descriptions of mutants in which petals replace stamens, giving doubleflow-ers, go back to ancient Greece and Rome. Similar accounts can be found in the botanical literature of China more than a thousand years ago, and in the books of the herbalists of Renaissance Europe (Meyerowitz et al., 1989). The use of such mutants (and similar but noninherited developmental abnormalities) to understand developmental processes in plants is more recent, dating from Linnaeus in the mid-eighteenth century(seeCullen and Stevens, 1990), and from Goethe (1790), who derived the ideas of organ homology and homological comparison from plants showing what was then called abnormal metamorphosis. Our term homeosi