Guard cell signal transduction

Guard cells surround stomatal pores in the epidermis of plant leaves and st ems. Stomatal pore opening is essential for CO2 influx into leaves for phot osynthetic carbon fixation. In exchange, plants lose over 95% of their wate r via transpiration to the atmosphere. Signal transduction mechanisms in gu ard cells integrate hormonal stimuli, Light signals, water status, CO2, tem perature, and other environmental conditions to modulate stomatal apertures for regulation of gas exchange and plant survival under diverse conditions . Stomatal guard cells have become a highly developed model system for char acterizing early signal transduction mechanisms in plants and for elucidati ng how individual signaling mechanisms can interact within a network in a s ingle cell. In this review we focus on recent advances in understanding sig nal transduction mechanisms in guard cells.