UVR8-mediated inhibition of shade avoidance involves HFR1 stabilization in Arabidopsis

Autoři: Eleni Tavridou aff001;  Emanuel Schmid-Siegert aff003;  Christian Fankhauser aff004;  Roman Ulm aff001
Působiště autorů: Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, CH, Geneva, Switzerland aff001;  Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland aff002;  SIB-Swiss Institute of Bioinformatics, University of Lausanne, CH, Lausanne, Switzerland aff003;  Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH, Lausanne, Switzerland aff004
Vyšlo v časopise: UVR8-mediated inhibition of shade avoidance involves HFR1 stabilization in Arabidopsis. PLoS Genet 16(5): e32767. doi:10.1371/journal.pgen.1008797
Kategorie: Research Article
doi: 10.1371/journal.pgen.1008797


Sun-loving plants perceive the proximity of potential light-competing neighboring plants as a reduction in the red:far-red ratio (R:FR), which elicits a suite of responses called the “shade avoidance syndrome” (SAS). Changes in R:FR are primarily perceived by phytochrome B (phyB), whereas UV-B perceived by UV RESISTANCE LOCUS 8 (UVR8) elicits opposing responses to provide a counterbalance to SAS, including reduced shade-induced hypocotyl and petiole elongation. Here we show at the genome-wide level that UVR8 broadly suppresses shade-induced gene expression. A subset of this gene regulation is dependent on the UVR8-stabilized atypical bHLH transcription regulator LONG HYPOCOTYL IN FAR-RED 1 (HFR1), which functions in part redundantly with PHYTOCHROME INTERACTING FACTOR 3-LIKE 1 (PIL1). In parallel, UVR8 signaling decreases protein levels of the key positive regulators of SAS, namely the bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5, in a COP1-dependent but HFR1-independent manner. We propose that UV-B antagonizes SAS via two mechanisms: degradation of PIF4 and PIF5, and HFR1- and PIL1-mediated inhibition of PIF4 and PIF5 function. This work highlights the importance of typical and atypical bHLH transcription regulators for the integration of light signals from different photoreceptors and provides further mechanistic insight into the crosstalk of UVR8 signaling and SAS.

Klíčová slova:

Gene expression – Hypocotyl – Marker genes – Regulator genes – Seedlings – Transcriptional control – Ultraviolet B – White light


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