Phytochrome B inhibits binding of phytochrome‐interacting factors to their target promoters

Park, Eunae; Park, Jeongmoo; Kim, Jung-Hyun; Nagatani, Akira; Lagarias, J. Clark; Choi, Giltsu

doi:10.1111/j.1365-313x.2012.05114.x

Cited by 153 publications

(155 citation statements)

References 62 publications

(87 reference statements)

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“…It has previously been shown that NGB inhibits PIF3 activity by removing PIF3 from the promoters of its target genes and that this activity of NGB is Pfr dependent (Park et al, 2012). Our results are consistent with this report in that an FR pulse can release the repression of PIF targets by NGB (Fig.…”

Section: Photobody Localization Of Phyb Tightly Correlates With the Rsupporting

confidence: 93%

“…2B). This result confirms the observations from previous reports by Choi and colleagues, who showed, using transgenic lines overexpressing His-and Myctagged PIF3, that NGB fails to degrade PIF3 in continuous R (Park et al, , 2012. Second, in all three conditions tested, the 10 mmol m 22 s 21 R-to-D transition (Figs.…”

Section: Photobody Localization Of Phyb Tightly Correlates With the Rsupporting

confidence: 91%

“…In striking contrast, PIF3 accumulated in NGB and phyB-9 in continuous R and after the R-to-D transition (Fig. 2B); our observation that the NGB line fails to degrade PIF3 in the light is consistent with a recent report from Park et al (2012). Because the steady-state mRNA levels of PIF3 were comparable between PBG and NGB seedlings during the R-to-D transition (Supplemental Fig.…”

Section: Pbg But Not Ngb Can Repress Pif3 Accumulation In Both Thesupporting

confidence: 91%

“…First, most PIF proteins are stable only in the dark; in the light, photoactivated phytochromes bind directly to PIFs and trigger their phosphorylation and subsequent degradation in the light (Al-Sady et al, 2006;Lorrain et al, 2008;Shen et al, 2008;Leivar and Quail, 2011;Ni et al, 2013). Second, phytochromes can inhibit the transcriptional activity of PIF1 and PIF3 by removing them from the promoters of their target genes (Park et al, 2012).…”

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confidence: 99%

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Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark

et al. 2014

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Photobody localization of Arabidopsis (Arabidopsis thaliana) phytochrome B (phyB) fused to green fluorescent protein (PBG) correlates closely with the photoinhibition of hypocotyl elongation. However, the amino-terminal half of phyB fused to green fluorescent protein (NGB) is hypersensitive to light despite its inability to localize to photobodies. Therefore, the significance of photobodies in regulating hypocotyl growth remains debatable. Accumulating evidence indicates that under diurnal conditions, photoactivated phyB persists into darkness to inhibit hypocotyl elongation. Here, we examine whether photobodies are involved in inhibiting hypocotyl growth in darkness by comparing the PBG and NGB lines after the red light-to-dark transition. Surprisingly, after the transition from 10 mmol m 22 s 21 red light to darkness, PBG inhibits hypocotyl elongation three times longer than NGB. The disassembly of photobodies in PBG hypocotyl nuclei correlates tightly with the accumulation of the growth-promoting transcription factor PHYTOCHROME-INTERACTING FACTOR3 (PIF3). Destabilizing photobodies by either decreasing the light intensity or adding monochromatic far-red light treatment before the light-to-dark transition leads to faster PIF3 accumulation and a dramatic reduction in the capacity for hypocotyl growth inhibition in PBG. In contrast, NGB is defective in PIF3 degradation, and its hypocotyl growth in the dark is nearly unresponsive to changes in light conditions. Together, our results support the model that photobodies are required for the prolonged, light-dependent inhibition of hypocotyl elongation in the dark by repressing PIF3 accumulation and by stabilizing the far-red light-absorbing form of phyB. Our study suggests that photobody localization patterns of phyB could serve as instructive cues that control light-dependent photomorphogenetic responses in the dark.

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Section: Photobody Localization Of Phyb Tightly Correlates With the Rsupporting

confidence: 93%

Section: Photobody Localization Of Phyb Tightly Correlates With the Rsupporting

confidence: 91%

Section: Pbg But Not Ngb Can Repress Pif3 Accumulation In Both Thesupporting

confidence: 91%

mentioning

confidence: 99%

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Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark

et al. 2014

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“…It has been shown that phyB binds to PIF1/PIF3 and inhibits PIF1/PIF3-binding activity to their target promoters using in vivo ChIP assays (Park et al, 2012). Thus, phytochromes inhibit PIF function using two distinct mechanisms (i.e.…”

Section: Factors Inhibiting the Dna-binding Ability Of Pifsmentioning

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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slim shady is a novel allele of PHYTOCHROME B present in the T‐DNA line SALK_015201

Dash

McEwan²,

Montes

et al. 2021

Plant Direct

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Auxin is a hormone that is required for hypocotyl elongation during seedling development. In response to auxin, rapid changes in transcript and protein abundance occur in hypocotyls, and some auxin responsive gene expression is linked to hypocotyl growth. To functionally validate proteomic studies, a reverse genetics screen was performed on mutants in auxin‐regulated proteins to identify novel regulators of plant growth. This uncovered a long hypocotyl mutant, which we called slim shady , in an annotated insertion line in IMMUNOREGULATORY RNA‐BINDING PROTEIN ( IRR ). Overexpression of the IRR gene failed to rescue the slim shady phenotype and characterization of a second T‐DNA allele of IRR found that it had a wild‐type (WT) hypocotyl length. The slim shady mutant has an elevated expression of numerous genes associated with the brassinosteroid‐auxin‐phytochrome (BAP) regulatory module compared to WT, including transcription factors that regulate brassinosteroid, auxin, and phytochrome pathways. Additionally, slim shady seedlings fail to exhibit a strong transcriptional response to auxin. Using whole genome sequence data and genetic complementation analysis with SALK_015201C, we determined that a novel single nucleotide polymorphism in PHYTOCHROME B was responsible for the slim shady phenotype. This is predicted to induce a frameshift and premature stop codon at leucine 1125, within the histidine kinase‐related domain of the carboxy terminus of PHYB, which is required for phytochrome signaling and function. Genetic complementation analyses with phyb‐9 confirmed that slim shady is a mutant allele of PHYB . This study advances our understanding of the molecular mechanisms in seedling development, by furthering our understanding of how light signaling is linked to auxin‐dependent cell elongation. Furthermore, this study highlights the importance of confirming the genetic identity of research material before attributing phenotypes to known mutations sourced from T‐DNA stocks.

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Phytochrome B inhibits binding of phytochrome‐interacting factors to their target promoters

Cited by 153 publications

References 62 publications

Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark

Photobody Localization of Phytochrome B Is Tightly Correlated with Prolonged and Light-Dependent Inhibition of Hypocotyl Elongation in the Dark

Phytochromes and Phytochrome Interacting Factors

slim shady is a novel allele of PHYTOCHROME B present in the T‐DNA line SALK_015201

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