Functional interaction of the circadian clock and UV RESISTANCE LOCUS 8-controlled UV-B signaling pathways in Arabidopsis thaliana

Balázs Fehér, Lászlõ Kozma-Bognár, Éva Kevei, Anita Hajdu, Melanie Binkert, Seth Jon Davis, Eberhard Schäfer, Roman Ulm, Ferenc Nagy

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

Circadian clocks regulate many molecular and physiological processes in Arabidopsis (Arabidopsis thaliana), allowing the timing of these processes to occur at the most appropriate time of the day in a 24-h period. The accuracy of timing relies on the synchrony of the clock and the environmental day/night cycle. Visible light is the most potent signal for such synchronization, but light-induced responses are also rhythmically attenuated (gated) by the clock. Here, we report a similar mutual interaction of the circadian clock and non-damaging photomorphogenic UV-B light. We show that low-intensity UV-B radiation acts as entraining signal for the clock. UV RESISTANCE LOCUS 8 (UVR8) and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) are required, but ELONGATED HYPOCOTYL 5 (HY5) and HY5 HOMOLOG (HYH) are dispensable for this process. UV-B responsiveness of clock gene expression suggests that photomorphogenic UV-B entrains the plant clock through transcriptional activation. We also demonstrate that UV-B induction of gene expression under these conditions is gated by the clock in a HY5/HYH-independent manner. The arrhythmic early flowering 3-4 mutant showed non-gated, high-level gene induction by UV-B, yet displayed no increased tolerance to UV-B stress. Thus, the temporal restriction of UV-B responsiveness by the circadian clock can be considered as saving resources during acclimation without losing fitness.

Original languageEnglish
Pages (from-to)37-48
Number of pages12
JournalPlant Journal
Volume67
Issue number1
DOIs
Publication statusPublished - Jul 1 2011

Keywords

  • UV-B tolerance
  • circadian clock
  • circadian gating
  • entrainment
  • gene expression
  • ultraviolet-B light

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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