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Curr Biol. 2017 Jan 9;27(1):120-127. doi: 10.1016/j.cub.2016.11.004. Epub 2016 Dec 15.

UV-B Perceived by the UVR8 Photoreceptor Inhibits Plant Thermomorphogenesis.

Author information

1
School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK; Plant Ecophysiology, Institute of Environmental Biology (IEB), Utrecht University, Padualaan 8, 3584 Utrecht, the Netherlands.
2
School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK.
3
Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
4
Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, 1211 Geneva 4, Switzerland.
5
Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
6
School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK. Electronic address: kerry.franklin@bristol.ac.uk.

Abstract

Small increases in ambient temperature can elicit striking effects on plant architecture, collectively termed thermomorphogenesis [1]. In Arabidopsis thaliana, these include marked stem elongation and leaf elevation, responses that have been predicted to enhance leaf cooling [2-5]. Thermomorphogenesis requires increased auxin biosynthesis, mediated by the bHLH transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) [6-8], and enhanced stability of the auxin co-receptor TIR1, involving HEAT SHOCK PROTEIN 90 (HSP90) [9]. High-temperature-mediated hypocotyl elongation additionally involves localized changes in auxin metabolism, mediated by the indole-3-acetic acid (IAA)-amido synthetase Gretchen Hagen 3 (GH3).17 [10]. Here we show that ultraviolet-B light (UV-B) perceived by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8) [11] strongly attenuates thermomorphogenesis via multiple mechanisms inhibiting PIF4 activity. Suppression of thermomorphogenesis involves UVR8 and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1)-mediated repression of PIF4 transcript accumulation, reducing PIF4 abundance. UV-B also stabilizes the bHLH protein LONG HYPOCOTYL IN FAR RED (HFR1), which can bind to and inhibit PIF4 function. Collectively, our results demonstrate complex crosstalk between UV-B and high-temperature signaling. As plants grown in sunlight would most likely experience concomitant elevations in UV-B and ambient temperature, elucidating how these pathways are integrated is of key importance to the understanding of plant development in natural environments.

KEYWORDS:

Arabidopsis; HFR1; PIF4; UV-B; UVR8; auxin; high temperature; hypocotyl

PMID:
27989670
PMCID:
PMC5226890
DOI:
10.1016/j.cub.2016.11.004
[Indexed for MEDLINE]
Free PMC Article

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