UVR8 in Arabidopsis thaliana regulates multiple aspects of cellular differentiation during leaf development in response to ultraviolet B radiation

Abstract

Summary• Responses specific to ultraviolet B (UV-B) wavelengths are still poorly understood, both in terms of initial signalling and effects on morphogenesis. Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is the only known UV-B specific signalling component, but the role of UVR8 in leaf morphogenesis is unknown.• The regulatory effects of UVR8 on leaf morphogenesis at a range of supplementary UV-B doses were characterized, revealing both UVR8-dependent and independent responses to UV irradiation.• Inhibition of epidermal cell division in response to UV-B is largely independent of UVR8. However, overall leaf growth under UV-B irradiation in wild-type plants is enhanced compared with a uvr8 mutant because of a UVR8-dependent compensatory increase of cell area in wild-type plants. UVR8 was also required for the regulation of endopolyploidy in response to UV-B, and the uvr8 mutant also has a lower density of stomata than the wild type in the presence of UV-B, indicating that UVR8 has a regulatory role in other developmental events.• Our findings show that, in addition to regulating UV-protective gene expression responses, UVR8 is involved in controlling aspects of leaf growth and morphogenesis. This work extends our understanding of how UV-B response is orchestrated at the whole-plant level.

Retracted: Nitric oxide enhances plant ultraviolet‐B protection up‐regulating gene expression of the phenylpropanoid biosynthetic pathway

“…Moreover, UVR8 is also involved in the regulation of leaf growth and morphogenesis during UV-B response (Wargent et al 2009). It was recently reported that MYB12 is one of the target genes of HY5 (Stracke et al 2010).…”

Reversion of the Arabidopsis UV-B photoreceptor UVR8 to the homodimeric ground state

“…Specific UV-B perception is facilitated by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8) identified only recently in Arabidopsis (7). In agreement with its photoreceptor function, uvr8 null mutants show a strongly reduced response to UV-B (8)(9)(10)(11), which even is absent under conditions specifically activating UV-B photoreceptor responses (4). In contrast, UV-B stress responses are not affected per se in uvr8 mutants (12).…”

Ultraviolet-B-Induced Stomatal Closure in Arabidopsis Is Regulated by the UV RESISTANCE LOCUS8 Photoreceptor in a Nitric Oxide-Dependent Mechanism

“…It has been demonstrated recently that Arabidopsis UVR8 is a UV-B photoreceptor, regulating the expression of genes involved in UV-B responses (Brown et al, 2005;Favory et al, 2009;Rizzini et al, 2011;Christie et al, 2012;Wu et al, 2012). Some photomorphogenic responses driven by UVR8 influence plant morphology (Favory et al, 2009;Wargent et al, 2009). Furthermore, UVR8 regulates the stomatal index in response to UV-B (Wargent et al, 2009).…”

“…HY5, sometimes acting redundantly with the closely related HY5 HOMOLOG (HYH), mediates many gene expression responses regulated by UVR8 (Brown et al, 2005;Brown and Jenkins, 2008;Favory et al, 2009). UVR8 regulates morphogenic responses to UV-B, such as inhibition of hypocotyl elongation (Favory et al, 2009), and is necessary for the UV-B-stimulated increase in stomatal index (Wargent et al, 2009).…”