Progress in the molecular genetic analysis of trichome initiation and morphogenesis in Arabidopsis

Arabidopsis trichomes are large unicellular structures that develop on the surface of most shoot-derived organs. In leaves, the number, spacing and sh ape of trichomes is tightly regulated, and this process has been used as an experimental system to study the control of cell fate and pattern formatio n, The control of trichome initiation is complex: both the potential of a c ell to adopt the trichome cell fate and an intricate signaling pathway dete rmine the pattern of trichome initiation events. Several important new resu lts suggest that trichome initiation and morphogenesis are redundantly regu lated by both positive and negative factors. A testable model for the contr ol of trichome initiation is presented.