Ultraviolet-B-induced stomatal closure in Arabidopsis is regulated by the UV RESISTANCE LOCUS8 photoreceptor in a nitric oxide-dependent mechanism.
by Tossi V., Lamattina L., Jenkins G. I., Cassia R. O. (2014)
Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CC1245 (7600) Mar del Plata, Argentina.
in Plant Physiology 164, 2220–2230. –
UV RESISTANCE LOCUS8 (UVR8) signaling involves CONSTITUTIVELY PHOTOMORPHOGENIC1, the ELONGATED HYPOCOTYL5 (HY5) transcription factor, and the closely related HY5 HOMOLOG. Some UV-B responses mediated by UVR8 are also regulated by nitric oxide (NO), a bioactive molecule that orchestrates a wide range of processes in plants.
In this study, we investigated the participation of the UVR8 pathway and its interaction with NO in UV-B-induced stomatal movements in Arabidopsis (Arabidopsis thaliana).
Stomata in abaxial epidermal strips of Arabidopsis ecotype Landsberg erecta closed in response to increasing UV-B fluence rates, with maximal closure after 3-h exposure to 5.46 μmol m⁻² s⁻¹ UV-B. Both hydrogen peroxide (H₂O₂) and NO increased in response to UV-B, and stomatal closure was maintained by NO up to 24 h after the beginning of exposure.
Stomata of plants expressing bacterial NO dioxygenase, which prevents NO accumulation, did not close in response to UV-B, although H₂O₂ still increased. When the uvr8-1 null mutant was exposed to UV-B, stomata remained open, irrespective of the fluence rate.
Neither NO nor H₂O₂ increased in stomata of the uvr8-1 mutant. However, the NO donor S-nitrosoglutathione induced closure of uvr8-1 stomata to the same extent as in the wild type.
Experiments with mutants in UVR8 signaling components implicated CONSTITUTIVELY PHOTOMORPHOGENIC1, HY5, and HY5 HOMOLOG in UV-B-induced stomatal closure.
This research provides evidence that the UVR8 pathway regulates stomatal closure by a mechanism involving both H₂O₂ and NO generation in response to UV-B exposure.