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Regulation of flowering time by light quality


The transition to flowering in plants is regulated by environmental factors such as temperature and light1. Plants grown under dense canopies or at high density perceive a decrease in the ratio of red to far-red incoming light. This change in light quality serves as a warning of competition, triggering a series of responses known collectively as the ‘shade-avoidance syndrome’. During shade avoidance, stems elongate at the expense of leaf expansion, and flowering is accelerated2,3. Of the five phytochromes—a family of red/far-red light photoreceptors—in Arabidopsis, phytochrome B (phyB) has the most significant role in shade-avoidance responses4,5, but the mechanisms by which phyB regulates flowering in response to altered ratios of red to far-red light are largely unknown. Here we identify PFT1 (PHYTOCHROME AND FLOWERING TIME 1), a nuclear protein that acts in a phyB pathway and induces flowering in response to suboptimal light conditions. PFT1 functions downstream of phyB to regulate the expression of FLOWERING LOCUS T (FT), providing evidence for the existence of a light-quality pathway that regulates flowering time in plants.

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Figure 1: Phenotypes of pft1, phyA and phyB single, double and triple mutants.
Figure 2: Molecular characterization of PFT1.
Figure 3: FT and CO mRNA levels in WT, phyB, pft1 and pft1 phyB mutants.
Figure 4: PFT1 acts in a light-quality pathway upstream of FT.


  1. 1

    Levy, Y. Y. & Dean, C. Control of flowering time. Curr. Opin. Plant Biol. 1, 49–54 (1998)

    CAS  Article  Google Scholar 

  2. 2

    Ballare, C. L. Keeping up with the neighbours: phytochrome sensing and other signalling mechanisms. Trends Plant Sci. 4, 201 (1999)

    CAS  Article  Google Scholar 

  3. 3

    Halliday, K. J., Koornneef, M. & Whitelam, G. C. Phytochrome B and at least one other phytochrome mediate the accelerated flowering response of Arabidopsis thaliana L. to low red/far-red ratio. Plant Physiol. 104, 1311–1315 (1994)

    CAS  Article  Google Scholar 

  4. 4

    Aukerman, M. J. et al. A deletion in the PHYD gene of the Arabidopsis Wassilewskija ecotype defines a role for phytochrome D in red/far-red light sensing. Plant Cell 9, 1317–1326 (1997)

    CAS  PubMed  PubMed Central  Google Scholar 

  5. 5

    Devlin, P. F., Patel, S. R. & Whitelam, G. C. Phytochrome E influences internode elongation and flowering time in Arabidopsis. Plant Cell 10, 1479–1487 (1998)

    CAS  Article  Google Scholar 

  6. 6

    Lin, C. Photoreceptors and regulation of flowering time. Plant Physiol. 123, 39–50 (2000)

    CAS  Article  Google Scholar 

  7. 7

    Quail, P. H. Phytochrome photosensory signalling networks. Nature. Rev. Mol. Cell Biol. 3, 85–93 (2002)

    CAS  Article  Google Scholar 

  8. 8

    Yanovsky, M. J. & Kay, S. A. Molecular basis of seasonal time measurement in Arabidopsis. Nature 419, 308–312 (2002)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Simpson, G. G. & Dean, C. Arabidopsis, the Rosetta stone of flowering time? Science 296, 285–289 (2002)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Cerdan, P. D. et al. Regulation of phytochrome B signaling by phytochrome A and FHY1 in Arabidopsis thaliana. Plant J. 18, 499–507 (1999)

    CAS  Article  Google Scholar 

  11. 11

    Hennig, L., Poppe, C., Sweere, U., Martin, A. & Schafer, E. Negative interference of endogenous phytochrome B with phytochrome A function in Arabidopsis. Plant Physiol. 125, 1036–1044 (2001)

    CAS  Article  Google Scholar 

  12. 12

    Mockler, T. et al. Regulation of photoperiodic flowering by Arabidopsis photoreceptors. Proc. Natl Acad. Sci. USA 100, 2140–2145 (2003)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Ponting, C. P., Schultz, J., Milpetz, F. & Bork, P. SMART: identification and annotation of domains from signalling and extracellular protein sequences. Nucleic Acids Res. 27, 229–232 (1999)

    CAS  Article  Google Scholar 

  14. 14

    Ponting, C. P., Aravind, L., Schultz, J., Bork, P. & Koonin, E. V. Eukaryotic signalling domain homologues in archaea and bacteria. Ancient ancestry and horizontal gene transfer. J. Mol. Biol. 289, 729–745 (1999)

    CAS  Article  Google Scholar 

  15. 15

    Escher, D., Bodmer-Glavas, M., Barberis, A. & Schaffner, W. Conservation of glutamine-rich transactivation function between yeast and humans. Mol. Cell. Biol. 20, 2774–2782 (2000)

    CAS  Article  Google Scholar 

  16. 16

    Hinshelwood, J. & Perkins, S. J. Metal-dependent conformational changes in a recombinant vWF-A domain from human factor B: a solution study by circular dichroism, fourier transform infrared and 1H NMR spectroscopy. J. Mol. Biol. 298, 135–147 (2000)

    CAS  Article  Google Scholar 

  17. 17

    Levy, Y. Y., Mesnage, S., Mylne, J. S., Gendall, A. R. & Dean, C. Multiple roles of Arabidopsis VRN1 in vernalization and flowering time control. Science 297, 243–246 (2002)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Kardailsky, I. et al. Activation tagging of the floral inducer FT. Science 286, 1962–1965 (1999)

    CAS  Article  Google Scholar 

  19. 19

    Kobayashi, Y., Kaya, H., Goto, K., Iwabuchi, M. & Araki, T. A pair of related genes with antagonistic roles in mediating flowering signals. Science 286, 1960–1962 (1999)

    CAS  Article  Google Scholar 

  20. 20

    Suarez-Lopez, P. et al. CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis. Nature 410, 1116–1120 (2001)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Blazquez, M. A. & Weigel, D. Independent regulation of flowering by phytochrome B and gibberellins in Arabidopsis. Plant Physiol. 120, 1025–1032 (1999)

    CAS  Article  Google Scholar 

  22. 22

    Putterill, J., Robson, F., Lee, K., Simon, R. & Coupland, G. The CONSTANS gene of Arabidopsis promotes flowering and encodes a protein showing similarities to zinc finger transcription factors. Cell 80, 847–857 (1995)

    CAS  Article  Google Scholar 

  23. 23

    Samach, A. et al. Distinct roles of CONSTANS target genes in reproductive development of Arabidopsis. Science 288, 1613–1616 (2000)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Hepworth, S. R., Valverde, F., Ravenscroft, D., Mouradov, A. & Coupland, G. Antagonistic regulation of flowering-time gene SOC1 by CONSTANS and FLC via separate promoter motifs. EMBO J. 21, 4327–4337 (2002)

    CAS  Article  Google Scholar 

  25. 25

    Lee, H. et al. The AGAMOUS-LIKE 20 MADS domain protein integrates floral inductive pathways in Arabidopsis. Genes Dev. 14, 2366–2376 (2000)

    CAS  Article  Google Scholar 

  26. 26

    Koornneef, M., Hanhart, C., Van Loenen-Martinet, P. & Blankestijn-de Vries, H. The effect of daylength on the transition to flowering in phytochrome-deficient, late-flowering and double mutants of Arabidopsis thaliana. Physiol. Plant 95, 260–266 (1995)

    CAS  Article  Google Scholar 

  27. 27

    Blazquez, M. A., Trenor, M. & Weigel, D. Independent control of gibberellin biosynthesis and flowering time by the circadian clock in Arabidopsis. Plant Physiol. 130, 1770–1775 (2002)

    CAS  Article  Google Scholar 

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We thank the Kasuza Research Institute and the Arabidopsis Stock Center for providing EST clone APZL03h11R and BAC F2J7, respectively; D. Weigel for providing FT- and CO-overexpressing lines, and for useful advice; P. Wigge, S. Mora-Garcia, D. Weigel, J. Nemhauser, M. Yanovsky and J. Casal for comments on the manuscript; L. Barden for figure preparation; and B. Smoot, N. Ga and M. Ledgerwood for technical assistance. This work was supported by a grant from the National Institutes of Health to J.C. (GM52413) and by the Howard Hughes Medical Institute. P.C. was a fellow of the PEW Latin American Fellows Program and Fundación Antorchas.

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Correspondence to Joanne Chory.

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Cerdán, P., Chory, J. Regulation of flowering time by light quality. Nature 423, 881–885 (2003).

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