Guard cell signal transduction network: advances in understanding abscisic acid, CO2, and Ca2+ signaling.
Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO(2) influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO(2) activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO(2) and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO(2)-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.
Kim
Tae-Houn
TH
University of California, San Diego, Division of Biological Sciences, La Jolla, California 92093-0116, USA. thkim@ucsd.edu
Böhmer
Maik
M
Hu
Honghong
H
Nishimura
Noriyuki
N
Schroeder
Julian I
JI
D000040:Abscisic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002245:Carbon Dioxide / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D015398:Signal Transduction
D002245:Carbon Dioxide; D000040:Abscisic Acid; D002118:Calcium