Stomatal cell biology

In the past two years, major advances in our knowledge of the cellular even ts involved in the formation of stomatal complexes, particularly those resp onsible for the establishment of the stomatal pattern, have been made. Thes e events are altered in the Arabidopsis mutants sdd1-1, tmm and flp. Molecu lar cloning of the SDD1 gene initiated the elucidation of the underlying mo lecular mechanisms. The proposed function of SDD1 as a processing protease provides a hint towards the involvement of a proteinaceous signal in the fo rmation of stomatal complexes.