Abstract
The molecular genetic analysis of Arabidopsis thaliana, a long-day (LD) plant, has identified a number of genes required for the photoperiodic control of flowering. However, very little is known about the molecular mechanisms of short-day plants. We studied rice to understand how the photoperiodic control of flowering is regulated in an SD plant. Over-expression of OsGI, a homolog of the Arabidopsis GIGANTEA (GI) gene in transgenic rice, caused late flowering under both SD and LD conditions. Expression of the rice homolog of the Arabidopsis CONSTANS (CO) gene was increased in the transgenic rice, while expression of the rice homolog of FLOWERING LOCUS T (FT) was suppressed. These results indicate that three key regulatory genes for the photoperiodic control of flowering are conserved between Arabidopsisand rice but regulation of the FT gene by CO was reversed, resulting in suppression of flowering in rice under LD conditions.
