African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12433

Full Length Research Paper

The role of N-terminal module of PhyB in modulating root and hypocotyl growth length in Arabidopsis

Njimona Ibrahim
  • Njimona Ibrahim
  • Institute of Medical Research and Medicinal Plants Studies (IMPM), Ministry of Scientific Research and Innovation, P. O. Box 6133, Yaounde, Cameroon.
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Baluška František
  • Baluška František
  • Institute of Cellular and Molecular Botanics (IZMB), University of Bonn, Bonn, Germany.
  • Google Scholar

  •  Received: 20 May 2020
  •  Accepted: 24 September 2021
  •  Published: 30 June 2022


Phytochrome belongs to red/far-red light family of photoreceptors. It exists in two spectral forms named red light absorbing form (Pr), said to be the inactive form and far-red light absorbing form (Pfr) which is the active form. This photoreceptor is structurally divided into two modules- the amino acid (N-) terminal photosensory module and caboxylic acid (C-) terminal His kinase-like catalytic output module. Five different types exist in Arabidopsis (PhyA-E). Roots and hypocotyls elongation in Arabidopsis is regulated by photoreceptors one class of which is phytochrome. The role of phytochrome B (PhyB) in red light responses has been established through studies using PhyB mutant and truncated versions. N-terminal module of PhyB containing 651 amino acids was shown to be biologically active in regulating photomorphogenesis. Meanwhile, the C-terminal module was long assumed to be involved in downstream signal transduction. Recently, this module was suggested to play a role in integrating red and blue light signaling to circadian clock. Here, the study shows that the C-terminal module of PhyB is needed for root growth and strongly modulates the root to hypocotyl ratio at 22°C. At an elevated temperature (34°C), this ratio was altered suggesting a role of this module in temperature signaling during plant growth.


Key words: Phytochrome, red/far-red, Roots, hypocotyls.