Local and regional signaling and pattern formation
Stomatal development requires coordination of cell fate, cell division and overall pattern. Stomata and their precursors exchange signals with neighbor epidermal cells, with underlying tissues and over long distances.  The multiple inputs and the discrete and easily scorable cell fate outputs combined with the ability to manipulate gene expression in specific cells makes the stomatal lineage an excellent in vivo system to test general principles of plant signal transduction.

MAPK signaling
Mitogen-activated protein kinase (MAPK) signaling networks are found in all eukaryotic organisms and modulate a wide variety of biological processes including cell division, developmental pathways (including stomatal development) and responses to abiotic and biotic stresses.  Plant genomes encode large gene families of MAPK pathway components, often making the precise functions of individual kinases difficult to ascertain. We use the discrete stages and phenotypes of the stomatal lineage to assay the contributions of individual MAPK pathway members to cell fate and proliferation.
 
Modulating pathways in different tissues
Most studies have treated stomatal development as a single pathway from selection of MMC to differentiation of GCs. However, superimposed on this common pathway are tissue-specific patterning rules; for example, stomata do not form over leaf midveins, they appear in alternate files in hypocotyls,  and are found at different densities on the top and bottom sides of leaves.  Two new mutants shed light on these regional rules.  challah and vst1 were isolated as suppressors of the receptor TMM’s tissue-specific stomatal mutant phenotypes.   The proteins encoded by these suppressors reveal that both new signals and additional levels of regulation on known stomatal signal transduction pathways contribute to regional differences in stomatal pattern.

Relevant lab publications

Abrash, E and DC Bergmann (2009) Regional specification of stomatal production by the putative ligand CHALLAH, in press

Lampard GR*, Macalister CA*, Bergmann DC (2008) Arabidopsis stomatal initiation is controlled by MAPK-mediated regulation of the bHLH SPEECHLESS. Science 2008 Nov 14;322(5904):1113-6. PMID: 19008449   * contributed equally

Bergmann DC, Lukowitz W, Somerville CR (2004) Stomatal development and pattern controlled by a MAPKK kinase. Science. 2004 Jun 4;304(5676):1494-7. PMID: 15178800

Funding by: NIH, DOE, HFSP