Interaction between the light quality and flowering time pathways in Arabidopsis

Plant J. 2009 Oct;60(2):257-67. doi: 10.1111/j.1365-313X.2009.03962.x. Epub 2009 Jul 29.


Flowering in Arabidopsis is accelerated by a reduced ratio of red light to far-red light (R/FR), which indicates the proximity of competitive vegetation. By exploiting the natural genetic variation in flowering time responses to low R/FR, we obtained further insight into the complex pathways that fine-tune the transition to flowering in Arabidopsis. The Bla-6 ecotype does not flower significantly earlier in response to low R/FR, but is still able to display other features of shade avoidance, suggesting branching of low R/FR signalling. Here we show that the muted flowering response of Bla-6 is due to high levels of the floral repressor FLOWERING LOCUS C (FLC), conferred by a combination of functional FLC and FRIGIDA (FRI) alleles with a 'weak'FY allele. The Bla-6 FY allele encodes a protein with a corrupted WW binding domain, and we provide evidence that this locus plays a key role in the natural variation in light quality-induced flowering in Arabidopsis. In Bla-6, FLC blocks promotion to flowering by reduced R/FR by inhibiting expression of the floral integrator FLOWERING LOCUS T (FT) in a dose-dependent manner. Reduction of FLC removes this obstruction, and Bla6 plants then exhibit strong induction of FT and flower early in response to a low R/FR signal. This paper illustrates the intricate interaction of environmental signals and genetic factors to regulate flowering in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / physiology
  • Arabidopsis / radiation effects*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Flowers / genetics
  • Flowers / physiology*
  • Gene Expression Regulation, Plant
  • Genotype
  • Light*
  • MADS Domain Proteins / genetics
  • MADS Domain Proteins / metabolism*
  • Phenotype
  • RNA Interference
  • RNA, Plant / genetics
  • mRNA Cleavage and Polyadenylation Factors / genetics
  • mRNA Cleavage and Polyadenylation Factors / metabolism


  • Arabidopsis Proteins
  • FLF protein, Arabidopsis
  • FRI protein, Arabidopsis
  • FT protein, Arabidopsis
  • FY protein, Arabidopsis
  • MADS Domain Proteins
  • RNA, Plant
  • mRNA Cleavage and Polyadenylation Factors