InterPro domain: IPR026211

GIGANTEA is involved in regulation of circadian rhythm, and in the control of the photoperiodic flowering.

Photoperiodic control of flowering is a vital developmental process in plants because it directly relates to successful reproduction [ 1 ].

In Arabidopsis, a long-day (LD) plant, flowering is promoted by long days and is delayed by short days. Mutations in the GIGANTEA (GI) gene delay flowering under long days but the effects are minimal under short days. It is believed that GI plays an important role in regulating the expression of flowering-time genes during the promotion of flowering by photo-period [ 2 ], and that it participates in a feedback loop of the plant circadian system [ 3 ]. In rice, a short day (SD) plant, GI acts as suppressor of flowering under short-day and long-day conditions [ 4 ].

The GI gene encodes a putative membrane protein containing 6 putative transmembrane (TM) domains [ 4 ]. The protein interacts with SPINDLY, a negative regulator of gibberellin signalling in Arabidopsis, via the latter's N-terminal array of 10 tetratricopeptide repeats [ 4 ].

1. Adaptation of photoperiodic control pathways produces short-day flowering in rice. Nature 422, 719-22
2. GIGANTEA: a circadian clock-controlled gene that regulates photoperiodic flowering in Arabidopsis and encodes a protein with several possible membrane-spanning domains. EMBO J. 18, 4679-88
3. Control of circadian rhythms and photoperiodic flowering by the Arabidopsis GIGANTEA gene. Science 285, 1579-82
4. SPINDLY and GIGANTEA interact and act in Arabidopsis thaliana pathways involved in light responses, flowering, and rhythms in cotyledon movements. Plant Cell 16, 1550-63