Interaction between the light quality and flowering time pathways in Arabidopsis.
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.
Adams
Sally
S
Department of Biology, University of Leicester, Leicester, UK. S.Adams.1@warwick.ac.uk
Allen
Trudie
T
Whitelam
Garry C
GC
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008027:Light; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D039221:mRNA Cleavage and Polyadenylation Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; C414613:FRI protein, Arabidopsis; C418905:FT protein, Arabidopsis; C518020:FY protein, Arabidopsis; D026161:MADS Domain Proteins; D018749:RNA, Plant; D039221:mRNA Cleavage and Polyadenylation Factors