<i>Arabidopsis</i> RUP2 represses UVR8-mediated flowering in noninductive photoperiods

Arongaus, Adriana Beatriz; Song, Ching; Pireyre, Marie; Glöckner, Nina; Galvão, Vinícius Costa; Albert, Andreas; Winkler, Jana Barbro; Fankhauser, Christian; Harter, Klaus; Ulm, Roman

doi:10.1101/gad.318592.118

Cited by 47 publications

(44 citation statements)

References 70 publications

(119 reference statements)

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“…Arabidopsis total RNA was isolated with Plant RNeasy kit (Qiagen, https://www.qiagen.com/) and treated with DNaseI according to the manufacturer’s instructions. Complementary DNA synthesis and quantitative real‐time PCR using PowerUp SYBR Green Master Mix reagents and a QuantStudio 5 real‐time PCR system (Thermo Fisher Scientific, https://www.thermofisher.com/) were performed as previously described (Arongaus et al , ). Gene‐specific primers used for XTR7 , YUC8 , IAA19 , IAA29 , RUP2 , HY5 and PP2A (reference gene) are listed in Table S4.…”

Section: Methodsmentioning

confidence: 99%

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

2019

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Summary Inhibition of hypocotyl growth is a well‐established UV‐B‐induced photomorphogenic response that is mediated by the UV‐B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, the molecular mechanism by which UVR8 signaling triggers inhibition of hypocotyl growth is poorly understood. The bZIP protein ELONGATED HYPOCOTYL 5 (HY5) functions as the main positive regulatory transcription factor in the UVR8 signaling pathway, with HY5‐HOMOLOG (HYH) playing a minor role. However, here we demonstrate that hy5 hyh double mutants maintain significant UVR8‐dependent hypocotyl growth inhibition. We identify UVR8‐dependent inhibition of the activities of bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 as part of the UVR8 signaling pathway, which results in inhibition of hypocotyl growth. The UVR8‐mediated repression of several hypocotyl elongation‐related genes is independent of HY5 and HYH but largely associated with UVR8‐dependent degradation of PIF4 and PIF5, a process that consequently diminishes PIF4/5 target promoter occupancy. Taken together, our data indicate that UVR8‐mediated inhibition of hypocotyl growth involves degradation of PIF4 and PIF5. These findings contribute to our mechanistic understanding of UVR8‐induced photomorphogenesis and further support the function of PIFs as integrators of different photoreceptor signaling pathways.

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Section: Methodsmentioning

confidence: 99%

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

2019

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“…(v/v) Triton X-100, 1 mM DTT, 2 mM Na 3 VO 4 , 2 mM NaF, 1% (v/v) Protease Inhibitor Cocktail (Sigma) and 50 μM MG132, as previously described (Arongaus et al, 2018).…”

Section: Protein Extraction and Immunoblottingmentioning

confidence: 99%

Plant photoreceptors and their signaling components compete for binding to the ubiquitin ligase COP1 using their VP-peptide motifs

Lau

Podolec

Chappuis

et al. 2019

Preprint

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Plants sense different parts of the sun's light spectrum using specialized photoreceptors, many of which signal through the E3 ubiquitin ligase COP1. Photoreceptor binding modulates COP1's ubiquitin ligase activity towards transcription factors. Here we analyze why many COP1-interacting transcription factors and photoreceptors harbor sequence-divergent Val-Pro (VP) peptide motifs. We demonstrate that VP motifs enable different light signaling components to bind to the WD40 domain of COP1 with various binding affinities. Crystal structures of the VP motifs of the UV-B photoreceptor UVR8 and the transcription factor HY5 in complex with COP1, quantitative binding assays and reverse genetic experiments together suggest that UVR8 and HY5 compete for the COP1 WD40 domain. Photoactivation of UVR8 leads to high-affinity cooperative binding of its VP domain and its photosensing core to COP1, interfering with the binding of COP1 to its substrate HY5. Functional UVR8 -VP motif chimeras suggest that UV-B signaling specificity resides in the UVR8 photoreceptor core, not its VP motif. Crystal structures of different COP1 -VP peptide complexes highlight sequence fingerprints required for COP1 targeting. The functionally distinct blue light receptors CRY1 and CRY2 also compete with downstream transcription factors for COP1 binding using similar VP-peptide motifs. Together, our work reveals that photoreceptors and

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“…There are several reports where FT expression was not detected under SD (Corbesier et al ., ; Jang et al ., , ; Sawa and Kay, ; Hiraoka et al ., ; Liu et al ., ) and others where FT expression was observed even under SD (Yanovsky and Kay, ; Imaizumi et al ., ; Takada and Goto, ; Balasubramanian et al ., ; Salazar et al ., ; Arongaus et al ., ). Because our explanation of the co phenotype requires FT activity under SD, we explored this issue in further detail.…”

Section: Resultsmentioning

confidence: 97%

CONSTANS delays Arabidopsis flowering under short days

et al. 2019

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These authors contributed equally to this work. SUMMARYLong days (LD) promote flowering of Arabidopsis thaliana compared with short days (SD) by activating the photoperiodic pathway. Here we show that growth under very-SD (3 h) or darkness (on sucrose) also accelerates flowering on a biological scale, indicating that SD actively repress flowering compared with very-SD. CONSTANS (CO) repressed flowering under SD, and the early flowering of co under SD required FLOWER-ING LOCUS T (FT). FT was expressed at a basal level in the leaves under SD, but these levels were not enhanced in co. This indicates that the action of CO in A. thaliana is not the mirror image of the action of its homologue in rice. In the apex, CO enhanced the expression of TERMINAL FLOWER 1 (TFL1) around the time when FT expression is important to promote flowering. Under SD, the tfl1 mutation was epistatic to co and in turn ft was epistatic to tfl1. These observations are consistent with the long-standing but not demonstrated model where CO can inhibit FT induction of flowering by affecting TFL1 expression.

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Arabidopsis RUP2 represses UVR8-mediated flowering in noninductive photoperiods

Cited by 47 publications

References 70 publications

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

Plant photoreceptors and their signaling components compete for binding to the ubiquitin ligase COP1 using their VP-peptide motifs

CONSTANS delays Arabidopsis flowering under short days

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