Plant homeobox genes: many functions stem from a common motif.

Homeodomain-containing transcription factors play a variety of important roles in plant, animal, and fungal development. Mutational and evolutionary analysis is beginning to pinpoint specific roles of homeobox genes in plant meristem function. Even though many different plant homeobox genes encode very similar homeodomain sequences, overexpression studies suggest the existence of several levels of regulation that may specify the functions of the different proteins. Recent analysis of the maize Knotted1 gene and its orthologue in barley demonstrates some of these regulatory processes.