Association of the circadian rhythmic expression of GmCRY1a with a latitudinal cline in photoperiodic flowering of soybean

Proc Natl Acad Sci U S A. 2008 Dec 30;105(52):21028-33. doi: 10.1073/pnas.0810585105. Epub 2008 Dec 23.


Photoperiodic control of flowering time is believed to affect latitudinal distribution of plants. The blue light receptor CRY2 regulates photoperiodic flowering in the experimental model plant Arabidopsis thaliana. However, it is unclear whether genetic variations affecting cryptochrome activity or expression is broadly associated with latitudinal distribution of plants. We report here an investigation of the function and expression of two cryptochromes in soybean, GmCRY1a and GmCRY2a. Soybean is a short-day (SD) crop commonly cultivated according to the photoperiodic sensitivity of cultivars. Both cultivated soybean (Glycine max) and its wild relative (G. soja) exhibit a strong latitudinal cline in photoperiodic flowering. Similar to their Arabidopsis counterparts, both GmCRY1a and GmCRY2a affected blue light inhibition of cell elongation, but only GmCRY2a underwent blue light- and 26S proteasome-dependent degradation. However, in contrast to Arabidopsis cryptochromes, soybean GmCRY1a, but not GmCRY2a, exhibited a strong activity promoting floral initiation, and the level of protein expression of GmCRY1a, but not GmCRY2a, oscillated with a circadian rhythm that has different phase characteristics in different photoperiods. Consistent with the hypothesis that GmCRY1a is a major regulator of photoperiodic flowering in soybean, the photoperiod-dependent circadian rhythmic expression of the GmCRY1a protein correlates with photoperiodic flowering and latitudinal distribution of soybean cultivars. We propose that genes affecting protein expression of the GmCRY1a protein play an important role in determining latitudinal distribution of soybeans.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis Proteins
  • Base Sequence
  • Circadian Rhythm / physiology*
  • Cryptochromes
  • Flavoproteins / biosynthesis*
  • Flavoproteins / genetics
  • Gene Expression Regulation, Enzymologic / physiology*
  • Gene Expression Regulation, Plant / physiology*
  • Glycine max / enzymology*
  • Glycine max / genetics
  • Glycine max / growth & development
  • Molecular Sequence Data
  • Plant Proteins / biosynthesis*
  • Plant Proteins / genetics
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism


  • Arabidopsis Proteins
  • CRY1 protein, Arabidopsis
  • Cryptochromes
  • Flavoproteins
  • Plant Proteins
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease

Associated data

  • GENBANK/DQ401046