Augé RM. 2000. Stomatal behavior of arbuscular mycorrhizal plants. In: Kapulnik Y, Douds DD (eds) Arbuscular Mycorrhizas: Physiology and Function, pp 201-237. Kluwer Academic Publishers, Dordrecht, the Netherlands. ISBN 0-7923-6444-9 Arbuscular mycorrhizal (AM) symbioses can affect the water balance of amply watered and droughted plants. The mycorrhizal influence most often examined within the field of water relations has been alteration of stomatal behavior. This review summarizes possible biophysical and biochemical mechanisms, discussing how AM-induced changes in tissue hydration, plant size, tissue elemental concentrations and nonhydraulic root-to-shoot signaling may affect stomatal regulation. The review also provides a brief catalog of published mycorrhizal effects on stomata behavior.