A Dof transcription Factor, SCAP1, is essential for the development of functional stomata in Arabidopsis.
Negi, J., Moriwaki, K., Konishi, M., Yokoyama, R., Nakano, T., Kusumi, K., Hashimoto-Sugimoto, M., Schroeder, J.I., Nishitani, K., Yanagisawa, S., Iba, K.
Current Biology 23: 479-484
Stomata are highly specialized organs that consist of pairs
of guard cells and regulate gas and water vapor exchange
in plants. Although early stages of guard cell differentiation
have been described and were interpreted in
analogy to processes of cell type differentiation in animals
, the downstream development of functional stomatal
guard cells remains poorly understood. We have isolated
an Arabidopsis mutant, stomatal carpenter 1 (scap1), that
develops irregularly shaped guard cells and lacks the ability
to control stomatal aperture, including CO2-induced
stomatal closing and light-induced stomatal opening.
SCAP1 was identified as a plant-specific Dof-type transcription
factor expressed in maturing guard cells, but not in
guard mother cells. SCAP1 regulates the expression of
genes encoding key elements of stomatal functioning and
morphogenesis, such as K+ channel protein, MYB60 transcription
factor, and pectin methylesterase. Consequently,
ion homeostasis was disturbed in scap1 guard cells, and
esterification of extracellular pectins was impaired so that
the cell walls lining the pores did not mature normally. We
conclude that SCAP1 regulates essential processes of
stomatal guard cell maturation and functions as a key transcription
factor regulating the final stages of guard cell