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GIGANTEA : a circadian clock‐controlled gene that regulates photoperiodic flowering in Arabidopsis and encodes a protein with several possible membrane‐spanning domains
Author(s) -
Fowler Sarah,
Lee Karen,
Onouchi Hitoshi,
Samach Alon,
Richardson Kim,
Morris Bret,
Coupland George,
Putterill Jo
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.17.4679
Subject(s) - biology , gigantea , arabidopsis , photoperiodism , circadian clock , genetics , gene , circadian rhythm , mutant , microbiology and biotechnology , botany , endocrinology
Flowering of Arabidopsis is promoted by long days and delayed by short days. Mutations in the GIGANTEA ( GI ) gene delay flowering under long days but have little or no effect under short days. We have now isolated the GI gene and show that it encodes a novel, putative membrane protein. By comparing the sequence of the Arabidopsis gene with that of a likely rice orthologue and by sequencing mutant alleles, we identify regions of the GI protein that are likely to be important for its function. We show that GI expression is regulated by the circadian clock with a peak in transcript levels 8–10 h after dawn. The timing, height and duration of this peak are influenced by daylength. We analysed the interactions between GI and the LHY , CCA1 and ELF3 genes, previously shown to affect daylength responses; we show that the rhythmic pattern of GI expression is altered in the elf3 , CCA1‐OX and lhy genotypes, and that CCA1 and LHY expression are reduced by gi mutations. Our results are consistent with the idea that GI plays an important role in regulating the expression of flowering time genes during the promotion of flowering by photoperiod.