Overexpression of rice phytochrome A partially complements phytochrome B deficiency in Arabidopsis

Planta. 1999 Jan;207(3):401-9. doi: 10.1007/s004250050498.


The red/far-red reversible phytochromes play a central role in regulating the development of plants in relation to their light environment. Studies on the roles of different members of the phytochrome family have mainly focused on light-labile, phytochrome A and light-stable, phytochrome B. Although these two phytochromes often regulate identical responses, they appear to have discrete photosensory functions. Thus, phytochrome A predominantly mediates responses to prolonged far-red light, as well as acting in a non-red/far-red-reversible manner in controlling responses to light pulses. In contrast, phytochrome B mediates responses to prolonged red light and acts photoreversibly under light-pulse conditions. However, it has been reported that rice (Oryza sativa L.) phytochrome A operates in a classical red/far-red reversible fashion following its expression in transgenic tobacco plants. Thus, it was of interest to determine whether transgenic rice phytochrome A could substitute for loss of phytochrome B in phyB mutants of Arabidopsis thaliana (L.) Heynh. We have observed that ectopic expression of rice phytochrome A can correct the reduced sensitivity of phyB hypocotyls to red light and restore their response to end-of-day far-red treatments. The latter is widely regarded as a hallmark of phytochrome B action. However, although transgenic rice phytochrome A can correct other aspects of elongation growth in the phyB mutant it does not restore other responses to end-of-day far-red treatments nor does it restore responses to low red:far-red ratio. Furthermore, transgenic rice phytochrome A does not correct the early-flowering phenotype of phyB seedlings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / metabolism
  • Arabidopsis / physiology
  • Arabidopsis Proteins
  • Gene Expression
  • Hypocotyl / growth & development
  • Light
  • Oryza / genetics
  • Photoreceptor Cells*
  • Phytochrome / biosynthesis
  • Phytochrome / genetics
  • Phytochrome / physiology*
  • Phytochrome A
  • Phytochrome B
  • Plants, Genetically Modified / physiology
  • Transcription Factors*


  • Arabidopsis Proteins
  • PHYA protein, Arabidopsis
  • PHYB protein, Arabidopsis
  • Phytochrome A
  • Transcription Factors
  • Phytochrome
  • Phytochrome B