Abstract
Ultraviolet-B (UV-B; 280–315 nm) light, which is an integral part of the solar radiation reaching the surface of the Earth, induces a broad range of physiological responses in plants. The UV RESISTANCE LOCUS 8 (UVR8) protein is the first and only light photoreceptor characterized to date that is specific for UV-B light and it regulates various aspects of plant growth and development in response to UV-B light. Despite its involvement in the control of important plant traits, most studies on UV-B photoreceptors have focused on Arabidopsis and no data on UVR8 function are available for forest trees. In this study, we isolated a homologue of the UV receptor UVR8 of Arabidopsis, PeUVR8, from Populus euphratica (Euphrates poplar) and analyzed its structure and function in detail. The deduced PeUVR8 amino acid sequence contained nine well-conserved regulator of chromosome condensation 1 (RCC1) repeats and the region 27 amino acids from the C terminus (C27) that interact with COP1 (CONSTITUTIVELY PHOTOMORPHOGENIC1). Secondary and tertiary structure analysis showed that PeUVR8 shares high similarity with the AtUVR8 protein from Arabidopsis thaliana. Using heterologous expression in Arabidopsis, we showed that PeUVR8 overexpression rescued the uvr8 mutant phenotype. In addition, PeUVR8 overexpression in wild-type background seedlings grown under UV-B light inhibited hypocotyl elongation and enhanced anthocyanin accumulation. Furthermore, we examined the interaction between PeUVR8 and AtCOP1 using a bimolecular fluorescence complementation (BiFC) assay. Our data provide evidence that PeUVR8 plays important roles in the control of photomorphogenesis in planta.
Highlights
Sunlight is important to plants both as the primary source of energy and as an environmental signal that regulates growth and development
To isolate a full-length cDNA sequence corresponding to the Euphrates poplar UV RESISTANCE LOCUS 8 (PeUVR8) gene, a Euphrates poplar expressed sequence tag (EST) clone with similarity to the Arabidopsis UVR8 gene was identified by mining the NCBI EST database for Euphrates poplar ESTs isolated from Euphrates poplar leaves
No fluorescence was observed in the control combination including the two empty vectors: pSPYNE-35S (YN) plus pSPYCE-35S (YC). These results suggested that PeUVR8 and AtCOP1 interact in vivo in plant cells (Fig 8), and provided additional evidence that PeUVR8 is the poplar counterpart of AtUVR8 and plays a role in the molecular mechanism of the UV-B light signal transduction pathway in poplar
Summary
Sunlight is important to plants both as the primary source of energy and as an environmental signal that regulates growth and development. Light promotes the developmental transition from skotomorphogenesis to photomorphogenesis in plants through the combinatorial. Analysis of PeUVR8 from Populus euphratica interaction of diverse sensory photoreceptors, which are classified based on the wavelength of light they perceive [1]. UV-B wavelengths impinge on the earth with highly variable spatial and time-dependent distributions [7]. While UV-B light is a source of damage, it is a source of information for plants. UV-B light causes altered flowering time, promotion of branching, reduced fertility, and reduced biomass production [8,9]. Nondamaging UV-B light evokes photomorphogenic responses including hypocotyl growth inhibition, cotyledon expansion, phototropic curvature, biosynthesis of anthocyanins and flavonoids, and stomatal opening [13,14,15,16,17]
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