Deconvoluting the interactions of phytochrome isoforms in regulating growth and development

Ferenc Nagy, Seth J Davis

Research output: Contribution to journalArticlepeer-review


Plants are sessile organisms, and to optimize fitness and competitiveness they must adapt to changing environments. Among the numerous environmental factors that drive adaptive growth in plants, light is arguably the most important signal. Here light is processed by intensity, wavelength and even through detecting ratios of colour combinations. Together these cues are processed to harmonize growth with the prevailing ambient environment. Plants have evolved a battery of highly specialized photoreceptors to perform the tasks of detecting the intricacies of the light environment, and these notably include the family of red (R) and far‐red (FR) light absorbing phytochromes (Chen & Chory 2011). Phytochromes (phy) are chromoproteins that exist as dimers, and each monomer contains a covalently linked open tetrapyrrole termed phytochromobilin (Davis 2006). In the model plant Arabidopsis thaliana, phytochrome apoproteins are encoded by a small multigene family consisting of PHYA, PHYB, PHYC, PHYD and PHYE (Clack et al. 1994). In rice, there are three such isoforms with presumed one‐to‐one orthologues for PHYA, PHYB and PHYC (Takano et al. 2005). In this issue of Plant, Cell & Environment, the tissue distribution of these rice PHY genes is reported (Baba‐Kasai et al. 2014). All of these encoded phys cycle between their biologically inactive (Pr) and active (Pfr) forms where they then translocate into the nucleus in a light‐dependent fashion. Nuclear‐localized phys (in a conformation‐dependent fashion) directly or indirectly regulate the activity/abundance of negative regulatory proteins such as CONSTITUTIVE MORPHOGENESIS‐1 (COP1) and SUPPRESSOR OF PHYTOCHROME A (SPA1‐4), and that of various transcription factors such as the PHYTOCHROME‐INTERACTING FACTORS (PIFs) (Chen & Chory 2011). Phys thus act as light quality/quantity‐dependent molecular switches to regulate expression of thousands of genes underlying photomorphogenic responses at all stages of plant development.
Original languageEnglish
Pages (from-to)2649-51
Number of pages3
JournalPlant, Cell and Environment
Issue number12
Publication statusPublished - Dec 2014


  • gene expression regulation
  • light
  • organ specificity
  • oryza sativa
  • phytochrome


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