Arabidopsis DE-ETIOLATED1 Represses Photomorphogenesis by Positively Regulating Phytochrome-Interacting Factors in the Dark

Dong, Jie; Tang, Dafang; Gao, Zhaoxu; Yu, Renbo; Li, Kunlun; He, Hang; Terzaghi, William; Deng, Xing Wang; Chen, Haodong

doi:10.1105/tpc.114.130666

Cited by 125 publications

(135 citation statements)

References 75 publications

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“…4D). Consistently, a recent study showed that DET1 interacted with and stabilized the PIF1 protein in etiolated seedlings (26). To illustrate the degradation dynamics of the PIF1 protein, we further performed a cell-free degradation assay.…”

Section: Det1 Genetically Acts Upstream Of Hfr1 and Pif1 In Repressinmentioning

confidence: 65%

Arabidopsis DET1 degrades HFR1 but stabilizes PIF1 to precisely regulate seed germination

Shi

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Seed is an essential propagation organ and a critical strategy adopted by terrestrial flowering plants to colonize the land. The ability of seeds to accurately respond to light is vital for plant survival. However, the underlying mechanism is largely unknown. In this study, we reveal a circuit of triple feed-forward loops adopted by Arabidopsis seeds to exclusively repress germination in dark conditions and precisely initiate germination under diverse light conditions. We identify that de-etiolated 1 (DET1), an evolutionarily conserved protein, is a central repressor of light-induced seed germination. Genetic analysis demonstrates that DET1 functions upstream of long hypocotyl in far-red 1 (HFR1) and phytochrome interacting factor 1 (PIF1), the key positive and negative transcription regulators in seed germination. We further find that DET1 and constitutive photomorphogenic 10 (COP10) target HFR1 for protein degradation by assembling a COP10-DET1-damaged DNA binding protein 1-cullin4 E3 ligase complex. Moreover, DET1 and COP10 directly interact with and promote the protein stability of PIF1. Computational modeling reveals that phytochrome B (phyB)-DET1-HFR1-PIF1 and phyB-DET1-Protease-PIF1 are new signaling pathways, independent of the previously identified phyB-PIF1 pathway, respectively mediating the rapid and time-lapse responses to light irradiation. The model-simulated results are highly consistent with their experimental validations, suggesting that our mathematical model captures the essence of Arabidopsis seed germination networks. Taken together, this study provides a comprehensive molecular framework for light-regulated seed germination, improving our understanding of how plants respond to changeable environments.S eed germination is controlled by a wide range of environmental factors to ensure that plants start a new lifecycle in favorable conditions. Among them, light plays a major role in initiating seed germination (1-4). Plants perceive light signals through distinct families of photoreceptors, in which the red light photoreceptor phytochrome B (phyB) mediates the initial phase of light-induced seed germination (3,(5)(6)(7)(8). Previous studies showed that in seeds, phyB modulates downstream regulatory networks through one of its interacting factors, phytochrome interacting factor 1 (PIF1) (9-11). PIF1 is a basic helix-loop-helix (bHLH) transcription factor that plays a primary role in repressing seed germination, and PIF1 proteins are highly accumulated in dark-incubated seeds (9, 10, 12). Under light irradiation, the light-activated phyB interacts with PIF1 to induce PIF1 phosphorylation and degradation via the 26S proteasome (12-16). Our recent study identified long hypocotyl in far-red 1 (HFR1) as a core transcription regulator in seed germination (17). HFR1 positively regulates seed germination by forming heterodimers with PIF1 to sequester PIF1 from binding to its target genes (17). The HFR1-PIF1 pair governs the transcriptional networks of light-initiated seed germination (17). However, how...

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Section: Det1 Genetically Acts Upstream Of Hfr1 and Pif1 In Repressinmentioning

confidence: 65%

Arabidopsis DET1 degrades HFR1 but stabilizes PIF1 to precisely regulate seed germination

Shi

Wang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…1). PIF1 and PIF3-5 are stabilized by DET1 in the dark 8 . These data suggest that the CUL4 COP1-SPA E3 ubiquitin ligase is involved in PIF1 degradation under these conditions, and that different PIF family members are differentially regulated by different E3 ubiquitin ligases both in the dark and light conditions.…”

Section: Discussionmentioning

confidence: 98%

“…Strikingly, PIF1 directly interacts with COP1 and SPA complex and acts as a cofactor of COP1 E3 ubiquitin ligase to synergistically degrade the positively acting factor HY5 to repress photomorphogenesis in the dark 7 . PIFs also interact with DET1 and synergistically repress photomorphogenesis in the dark 8 . Therefore, the COP/DET/SPA and PIF complexes act independently as well as synergistically to prevent seed germination and seedling emergence in the dark.…”

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confidence: 99%

CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1

et al. 2015

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Plants undergo contrasting developmental programs in dark and light. Photomorphogenesis, a light-adapted programme is repressed in the dark by the synergistic actions of CUL4 COP1-SPA E3 ubiquitin ligase and a subset of basic helix-loop-helix transcription factors called phytochrome interacting factors (PIFs). To promote photomorphogenesis, light activates the phytochrome family of sensory photoreceptors, which inhibits these repressors by poorly understood mechanisms. Here, we show that the CUL4 COP1-SPA E3 ubiquitin ligase is necessary for the light-induced degradation of PIF1 in Arabidopsis. The light-induced ubiquitylation and subsequent degradation of PIF1 is reduced in the cop1, spaQ and cul4 backgrounds. COP1, SPA1 and CUL4 preferentially form complexes with the phosphorylated forms of PIF1 in response to light. The cop1 and spaQ seeds display strong hyposensitive response to far-red light-mediated seed germination and light-regulated gene expression. These data show a mechanism by which an E3 ligase attenuates its activity by degrading its cofactor in response to light.

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“…3) and stabilizes PIFs. Strikingly, the degradation of PIFs in the det1 background is not mediated by the 26S proteasome pathway, as the inhibitors of the 26S proteasome failed to block PIF degradation in the det1 background (Dong et al, 2014). Further studies are In the dark, DET1 interacts with PIFs and stabilizes them by an unknown mechanism.…”

Section: Factors Controlling Pif Abundance Under Darknessmentioning

confidence: 99%

Phytochromes and Phytochrome Interacting Factors

2017

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The basic helix-loop-helix domain-containing transcription factors that interact physically with the red and far-red light photoreceptors, phytochromes, are called PHYTOCHROME INTERACTING FACTORS (PIFs). In the last two decades, the phytochrome-PIF signaling module has been shown to be conserved from Physcomitrella patens to higher plants. Exciting recent studies highlight the discovery of at least four distinct kinases (PPKs, CK2, BIN2, and phytochrome itself) and four families of ubiquitin ligases (SCF EBF 1/2 , CUL3 LRB , CUL3 BOP , and CUL4 COP1-SPA ) that regulate PIF abundance both in dark and light conditions. This review discusses these recent discoveries with a focus on the central phytochrome signaling mechanisms that have a profound impact on plant growth and development in response to light.

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Arabidopsis DE-ETIOLATED1 Represses Photomorphogenesis by Positively Regulating Phytochrome-Interacting Factors in the Dark

Cited by 125 publications

References 75 publications

Arabidopsis DET1 degrades HFR1 but stabilizes PIF1 to precisely regulate seed germination

Arabidopsis DET1 degrades HFR1 but stabilizes PIF1 to precisely regulate seed germination

CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1

Phytochromes and Phytochrome Interacting Factors

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