Basal stomatal aperture is regulated by GA-DELLAs in Arabidopsis.

Stomatal aperture is tightly regulated in order to achieve the best compromise between gas exchange and water conservation. Steady-state (basal) stomatal aperture is therefore understandably a key component in plant fitness. It has been shown previously in tomato that DELLA proteins act as positive regulators of closure of stomata, and their action is enhanced by the hormone ABA, which is itself important in mediating drought stress tolerance. DELLAs are regulated by a variety of signals which promote plant growth, most notably the hormones gibberellins, which have been shown to promote stomatal opening. We have found that DELLA proteins are also used in Arabidopsis for regulating basal stomatal aperture. We also discovered that the perception of endogenous gibberellins via the GID1 receptors is necessary for optimal basal stomatal aperture.