Seminars

Vital to the global carbon and water cycles, plant stomata are controllable pores on the epidermis of land plants that allow gas exchange for photosynthesis and respiration without unnecessary water loss.  Stomata appear in a nonrandom distribution on the plant surface, and never arise adjacent to each other.  The formation of stomata has recently emerged as a powerful system for understanding cell-cell signaling and development through asymmetric stem-cell divisions.  Stomatal development is controlled by combinatorial interactions of five basic-helix-loop-helix transcription factors, SPEECHLESS, MUTE, FAMA, SCRM, and SCRM2.  Recently we have developed a live imaging system to observe the development of individual cells over the first days following seed germination and assess the roles and expression timing of these master regulatory genes.  Focusing on SCRM, which is expressed strongly throughout the stomatal lineage, we found that cells expressing GFP-SCRM arise in pairs on the cotyledon epidermis, and that one cell differentiates into a stoma while its lower-fluorescence partner divides asymmetrically away from it.  Using this foundation, we investigate stomatal-lineage gene expression, cell signaling and transduction, and possible cell-fate change in the Arabidopsis cotyledon.