Calcium sensitivity and guard cells (Invited Review)

Stomatal aperture is regulated by the stress-induced phyto-hormone abscisic acid (ABA), and by CO₂ and Ca²⁺ concentrations. Hubbard et al. review the topic and propose models to explain the specificity of signalling for the common intermediate, intracellular Ca²⁺. These models are put in the context of recent research identifying ABA receptors. New genetic Ca²⁺-dependent protein kinase phenotypes and Ca²⁺ imaging analysis are presented in reference to these models, and the importance of measuring and tracking individual stomatal pore responses is introduced.