Unraveling the knots in plant development.

Homeobox genes, first discovered from studies of homeotic mutations in Drosophila, have recently been found in plants. The proteins encoded by homeobox genes thus join the ranks of other animal transcription factors that have plant developmental counterparts, suggesting that even though plant and animal development are very different, regulatory mechanisms that direct development may be shared among all higher eukaryotes. The role of homeobox genes in plants remains elusive; nonetheless, gain-of-function mutations of one homeobox gene, Knotted, profoundly affect development. The phenotype suggests that ectopic expression of Knotted in leaves causes cells to take on alternative fates.