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Acetylcholine (ACh) is an important neurochemical transmitter in animals; it also exists in plants and plays a significant role in various kinds of physiological functions in plants. ACh has been known to induce the stomatal opening. By monitoring the changes of cytosolic Ca2+ with fluorescent probe Fluo-3 AM under the confocal microscopy, we found that exogenous ACh increased cytosolic Ca2+ concentration of guard cells ofVicia faba L. Muscarine, an agonist of muscarine acetylcholine receptor (mAChR), could do so as well. In contrast, atropine, the antagonist of mAChR abolished the ability of ACh to increase Ca2+ in guard cells. This mechanism is similar to mAChR in animals. When EGTA was used to chelate Ca2+ or ruthenium red to block Ca2+ released from vacuole respectively, the results showed that the increased cytosolic Ca2+ mainly come from intracellular Ca2+ store. The evidence supports that Ca2+ is involved in guard-cell response to ACh and that Ca2+ signal is coupled to mAChRs in ACh signal transduction in guard cells. [ABSTRACT FROM AUTHOR]

Acetylcholine (ACh) is an important neurochemical transmitter in animals; it also exists in plants and plays a significant role in various kinds of physiological functions in plants. ACh has been known to induce the stomatal opening. By monitoring the changes of cytosolic Ca2+ with fluorescent probe Fluo-3 AM under the confocal microscopy, we found that exogenous ACh increased cytosolic Ca2+ concentration of guard cells of Vicia faba L. Muscarine, an agonist of muscarine acetylcholine receptor (mAChR), could do so as well. In contrast, atropine, the antagonist of mAChR abolished the ability of ACh to increase Ca2+ in guard cells. This mechanism is similar to mAChR in animals. When EGTA was used to chelate Ca2+ or ruthenium red to block Ca2+ released from vacuole respectively, the results showed that the increased cytosolic Ca2+ mainly come from intracellular Ca2+ store. The evidence supports that Ca2+ is involved in guard-cell response to ACh and that Ca2+ signal is coupled to mAChRs in ACh signal transduction in guard cells. [ABSTRACT FROM AUTHOR]

Discusses the involvement of Ca2+/CaM in the signal transduction of acetylcholine regulating stomatal movement. How the neutrotransmitter acetylcholine (ACh) is able to regulate the movement of stomata in plants; Demonstration that Ca2+/CaM are also involved in the ACh regulated stomatal movement.