Phytochrome Signaling

Quail, Peter H.

doi:10.1002/352760510x.ch7

Cited by 30 publications

(49 citation statements)

References 66 publications

(93 reference statements)

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“…Previously, positively acting components in phy signaling pathways have been described (Huq and Quail, 2005). Among those, HFR1, PRE6/KIDARI, PAR1, and PAR2 encode HLH proteins that function positively in light signaling pathways Fankhauser and Chory, 2000;Duek and Fankhauser, 2003;Hyun and Lee, 2006;Roig-Villanova et al, 2006;Zhou et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

A Negative Feedback Loop between PHYTOCHROME INTERACTING FACTORs and HECATE Proteins Fine-Tunes Photomorphogenesis in Arabidopsis

Zhu

Xin

et al. 2016

Plant Cell

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The phytochrome interacting factors (PIFs), a small group of basic helix-loop-helix transcription factors, repress photomorphogenesis both in the dark and light. Light signals perceived by the phytochrome family of photoreceptors induce rapid degradation of PIFs to promote photomorphogenesis. Here, we show that HECATE (HEC) proteins, another small group of HLH proteins, antagonistically regulate PIFs to promote photomorphogenesis. HEC1 and HEC2 heterodimerize with PIF family members. PIF1, HEC1, and HEC2 genes are spatially and temporally coexpressed, and HEC2 is localized in the nucleus. hec1, hec2, and hec3 single mutants and the hec1 hec2 double mutant showed hyposensitivity to light-induced seed germination and accumulation of chlorophyll and carotenoids, hallmark processes oppositely regulated by PIF1. HEC2 inhibits PIF1 target gene expression by directly heterodimerizing with PIF1 and preventing DNA binding and transcriptional activation activity of PIF1. Conversely, PIFs directly activate the expression of HEC1 and HEC2 in the dark, and light reduces the expression of these HECs possibly by degrading PIFs. HEC2 is partially degraded in the dark through the ubiquitin/26S-proteasome pathway and is stabilized by light. HEC2 overexpression also reduces the light-induced degradation of PIF1. Taken together, these data suggest that PIFs and HECs constitute a negative feedback loop to fine-tune photomorphogenesis in Arabidopsis thaliana.

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Section: Discussionmentioning

confidence: 99%

A Negative Feedback Loop between PHYTOCHROME INTERACTING FACTORs and HECATE Proteins Fine-Tunes Photomorphogenesis in Arabidopsis

Zhu

Xin

et al. 2016

Plant Cell

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“…The phy-mediated light signaling pathways involve both positively and negatively acting factors (Huq and Quail, 2005). For example, HFR1, HY5, LAF1 and others are the major positive regulators (Lau and Deng, 2012;Xu et al, 2015Xu et al, , 2016, whereas phytochrome-interacting factors (PIFs) act as major negative regulators of photomorphogenesis (Castillon et al, 2007;Leivar and Monte, 2014;Leivar and Quail, 2011).…”

Section: Introductionmentioning

confidence: 99%

Reciprocal proteasome-mediated degradation of PIFs and HFR1 underlies photomorphogenic development in Arabidopsis

Kathare

Pham

et al. 2017

Development

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The phytochrome-mediated regulation of photomorphogenesis under red and far-red light conditions involves both positively and negatively acting factors. The positively acting factors (e.g. HY5/HFR1/LAF1 and others) are degraded in the dark to prevent photomorphogenesis. By contrast, the negatively acting factors (e.g. phytochromeinteracting factors or PIFs) are degraded in response to light to promote photomorphogenesis. Here, we show that the negatively acting factor PIF1 is also degraded in the dark by direct heterodimerization with the positively acting factor HFR1. Conversely, PIF1 also promotes the degradation of HFR1 in darkness. PIF1 enhances the poly-ubiquitylation of HFR1 by COP1 in vivo and in vitro. In addition, the reciprocal co-degradation of PIF1 and HFR1 is dependent on the 26S proteasome pathway in vivo. Genetic evidence shows that the hfr1 mutant partially suppresses the constitutive photomorphogenic phenotypes of cop1-6 pif1 and of the quadruple mutant pifq both in the dark and in far-red light conditions. Taken together, these data uncover a co-degradation mechanism between PIFs and HFR1 that underlies photomorphogenic development in Arabidopsis thaliana.

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“…In the cytosol, the Pfr forms of phytochromes regulate the translation of mRNA (Paik et al, 2012). However, in the nucleus, phytochromes interact with multiple partners to modulate the transcription of downstream target genes to mediate light responses (Huq and Quail, 2005). One of the pivotal interacting partners is PHYTOCHROME INTERACTING FACTORs (PIFs), which act as a key regulator of the transition from skotomorphogenesis to photomorphogenesis (Castillon et al, 2007;Leivar and Quail, 2011).…”

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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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Phytochrome Signaling

Cited by 30 publications

References 66 publications

A Negative Feedback Loop between PHYTOCHROME INTERACTING FACTORs and HECATE Proteins Fine-Tunes Photomorphogenesis in Arabidopsis

A Negative Feedback Loop between PHYTOCHROME INTERACTING FACTORs and HECATE Proteins Fine-Tunes Photomorphogenesis in Arabidopsis

Reciprocal proteasome-mediated degradation of PIFs and HFR1 underlies photomorphogenic development in Arabidopsis

Phytochromes and Phytochrome Interacting Factors

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