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Leivar P, Martín G, Soy J, Dalton-Roesler J, Quail PH, Monte E. Phytochrome-imposed inhibition of PIF7 activity shapes photoperiodic growth in Arabidopsis together with PIF1, 3, 4 and 5. PHYSIOLOGIA PLANTARUM 2020; 169:452-466. [PMID: 32412656 DOI: 10.1111/ppl.13123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 05/29/2023]
Abstract
Under photoperiodic conditions, Arabidopsis thaliana seedling growth is inhibited in long days (LDs), but promoted under the extended nights of short days (SDs). This behavior is partly implemented by phytochrome (phy)-imposed oscillations in the abundance of the growth-promoting, phy-interacting bHLH transcription factors PHY-INTERACTING FACTOR 1 (PIF1), PIF3, PIF4 and PIF5 (PIF quartet or PIFq). However, the observation that a pifq mutant is still stimulated to elongate when given a phy-inactivating end-of-day far-red pulse (EODFR), suggests that additional factors are involved in the phy-mediated suppression of growth during the subsequent dark period. Here, by combining growth-analysis of pif7 single- and higher-order mutants with gene expression analysis under SD, LD, SD-EODFR, and LD-EODFR, we show that PIF7 promotes growth during the dark hours of SD, by regulating growth-related gene expression. Interestingly, the relative contribution of PIF7 in promoting growth is stronger under EODFR, whereas PIF3 role is more important under SD, suggesting that PIF7 is a prominent target of phy-suppression. Indeed, we show that phy imposes phosphorylation and inactivation of PIF7 during the light hours in SD, and prevents full dephosphorylation during the night. This repression can be lifted with an EODFR, which correlates with increased PIF7-mediated gene expression and elongation. In addition, our results suggest that PIF7 function might involve heterodimerization with PIF3. Furthermore, our data indicate that a pifqpif7 quintuple mutant is largely insensitive to photoperiod for hypocotyl elongation. Collectively, the data suggest that PIF7, together with the PIFq, is required for the photoperiodic regulation of seasonal growth.
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Affiliation(s)
- Pablo Leivar
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
- Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Barcelona, Spain
| | - Guiomar Martín
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
| | - Judit Soy
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
| | - Jutta Dalton-Roesler
- Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA, USA
- United States Department of Agriculture, Plant Gene Expression Center, Albany, CA, USA
| | - Peter H Quail
- Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA, USA
- United States Department of Agriculture, Plant Gene Expression Center, Albany, CA, USA
| | - Elena Monte
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
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Zhang L, Chen J, Li Q, Chen W. Transcriptome-wide analysis of basic helix-loop-helix transcription factors in Isatis indigotica and their methyl jasmonate responsive expression profiling. Gene 2015; 576:150-9. [PMID: 26449398 DOI: 10.1016/j.gene.2015.09.083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 09/06/2015] [Accepted: 09/30/2015] [Indexed: 01/06/2023]
Abstract
Jasmonates (JAs) act as conserved elicitors of plant secondary metabolism. JAs perception triggers extensive transcriptional reprogramming leading to activation of the entire metabolic pathways. The family of basic helix-loop-helix (bHLH) transcription factors (TFs) has essential roles in JA signaling; however, little is known about their roles in regulation of secondary metabolites in Isatis indigotica. In this study, we identified 78 putative IibHLH sequences using the annotation of I. indigotica transcriptome. The identified proteins were characterized based on phylogenetic and conserved motif analyses. Using RNA sequencing, 16 IibHLHs showed significant positive response to MeJA (methyl jasmonate) at 1h, indicating their roles as early signaling events of JA-mediated transcriptional reprogramming. Ten IibHLHs presented co-expression pattern with biosynthetic pathway genes, suggesting their regulating role in secondary metabolite synthesis. These gene expression profiling data indicate that bHLHs can be used as candidate genes in molecular breeding programs to improve metabolite production in I. indigotica.
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Affiliation(s)
- Lei Zhang
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China; Department of Pharmaceutical Botany, School of Pharmacy, Second Military Medical University, Shanghai 200433, China.
| | - Junfeng Chen
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.
| | - Qing Li
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.
| | - Wansheng Chen
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.
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Leivar P, Monte E. PIFs: systems integrators in plant development. THE PLANT CELL 2014; 26:56-78. [PMID: 24481072 PMCID: PMC3963594 DOI: 10.1105/tpc.113.120857] [Citation(s) in RCA: 385] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 01/03/2014] [Accepted: 01/14/2014] [Indexed: 05/17/2023]
Abstract
Phytochrome-interacting factors (PIFs) are members of the Arabidopsis thaliana basic helix-loop-helix family of transcriptional regulators that interact specifically with the active Pfr conformer of phytochrome (phy) photoreceptors. PIFs are central regulators of photomorphogenic development that act to promote stem growth, and this activity is reversed upon interaction with phy in response to light. Recently, significant progress has been made in defining the transcriptional networks directly regulated by PIFs, as well as the convergence of other signaling pathways on the PIFs to modulate growth. Here, we summarize and highlight these findings in the context of PIFs acting as integrators of light and other signals. We discuss progress in our understanding of the transcriptional and posttranslational regulation of PIFs that illustrates the integration of light with hormonal pathways and the circadian clock, and we review seedling hypocotyl growth as a paradigm of PIFs acting at the interface of these signals. Based on these advances, PIFs are emerging as required factors for growth, acting as central components of a regulatory node that integrates multiple internal and external signals to optimize plant development.
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