Arabidopsis Stomatal Initiation Is Controlled by MAPK-Mediated Regulation of the bHLH SPEECHLESS

• DOI: 10.1126/science.1162263
• Publication Date: 2008-11-13T21:47:59Z
• Authors: Gregory R. Lampard; Cora A. MacAlister; Dominique C. Berg...
• Keywords: 0303 health sciences; Arabidopsis Proteins; MAP Kinase Signaling System; Molecular Sequence Data; Arabidopsis; Plant Epidermis; Protein Structure, Tertiary; Plant Leaves; 03 medical and health sciences; Mutation; Plant Stomata; Basic Helix-Loop-Helix Transcription Factors; Amino Acid Sequence; Mitogen-Activated Protein Kinases; Phosphorylation; Cell Division

Stomata, epidermal structures that modulate gas exchange between plants and the atmosphere, play critical roles in primary productivity and the global climate. Positively acting transcription factors and negatively acting mitogen-activated protein kinase (MAPK) signaling control stomatal development in Arabidopsis ; however, it is not known how the opposing activities of these regulators are integrated. We found that a unique domain in a basic helix-loop-helix (bHLH) stomatal initiating factor, SPEECHLESS, renders it a MAPK phosphorylation target in vitro and modulates its function in vivo. MAPK cascades modulate a diverse set of activities including development, cell proliferation, and response to external stresses. The coupling of MAPK signaling to SPEECHLESS activity provides cell type specificity for MAPK output while allowing the integration of multiple developmental and environmental signals into the production and spacing of stomata.