Abstract
Plants detect different facets of their radiation environment via specific photoreceptors to modulate growth and development. UV-B is perceived by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8). The molecular mechanisms linking UVR8 activation to plant growth are not fully understood, however. When grown in close proximity to neighboring vegetation, shade-intolerant plants initiate dramatic stem elongation to overtop competitors. Here we show that UV-B, detected by UVR8, provides an unambiguous sunlight signal that inhibits shade avoidance responses in Arabidopsis thaliana by antagonizing the phytohormones auxin and gibberellin. UV-B triggers degradation of the transcription factors PHYTOCHROME INTERACTING FACTOR 4 and PHYTOCHROME INTERACTING FACTOR 5 and stabilizes growth-repressing DELLA proteins, inhibiting auxin biosynthesis via a dual mechanism. Our findings show that UVR8 signaling is closely integrated with other photoreceptor pathways to regulate auxin signaling and plant growth in sunlight.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arabidopsis / genetics
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Arabidopsis / metabolism*
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Arabidopsis / radiation effects*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Arabidopsis Proteins / radiation effects*
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Basic Helix-Loop-Helix Transcription Factors / genetics
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Basic Helix-Loop-Helix Transcription Factors / metabolism
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Basic-Leucine Zipper Transcription Factors / genetics
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Basic-Leucine Zipper Transcription Factors / metabolism
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism*
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Chromosomal Proteins, Non-Histone / radiation effects*
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DNA-Binding Proteins
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Genes, Plant
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Gibberellins / metabolism
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Gibberellins / radiation effects
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Indoleacetic Acids / antagonists & inhibitors
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Indoleacetic Acids / metabolism*
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Models, Biological
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Mutation
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Photoreceptors, Plant / genetics
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Photoreceptors, Plant / metabolism*
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Photoreceptors, Plant / radiation effects*
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Plants, Genetically Modified
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Protein Stability / radiation effects
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Proteolysis / radiation effects
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Signal Transduction / radiation effects
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Sunlight
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Ultraviolet Rays
Substances
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Arabidopsis Proteins
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Basic Helix-Loop-Helix Transcription Factors
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Basic-Leucine Zipper Transcription Factors
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Carrier Proteins
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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GAI protein, Arabidopsis
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Gibberellins
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HY5 protein, Arabidopsis
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HYH protein, Arabidopsis
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Indoleacetic Acids
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Nuclear Proteins
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PIF4 protein, Arabidopsis
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PIF5 protein, Arabidopsis
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Photoreceptors, Plant
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Uvr8 protein, Arabidopsis