Young Hun Song,1,2,* Jae Sung Shim,1,* Hannah A. Kinmonth-Schultz,1,* and Takato Imaizumi1
1Department of Biology, University of Washington, Seattle, Washington 98195-1800
2Department of Life Sciences, Ajou University, Suwon 443-749, Korea
*These authors contributed equally to this article.
Correspondence to Takato Imaizumi
Many plants use information about changing day length (photoperiod) to align their flowering time with seasonal changes to increase reproductive success. A mechanism for photoperiodic time measurement is present in leaves, and the day-length-specific induction of the FLOWERING LOCUS T (FT ) gene, which encodes florigen, is a major final output of the pathway. Here, we summarize the current understanding of the molecular mechanisms by which photoperiodic information is perceived in order to trigger FT expression in Arabidopsis as well as in the primary cereals wheat, barley, and rice. In these plants, the differences in photoperiod are measured by interactions between circadian-clock-regulated components, such as CONSTANS (CO), and light signaling. The interactions happen under certain day-length conditions, as previously predicted by the external coincidence model. In these plants, the coincidence mechanisms are governed by multilayered regulation with numerous conserved as well as unique regulatory components, highlighting the breadth of photoperiodic regulation across plant species
Keywords : photoperiodism, seasonal flowering, external coincidence model, CONSTANS, FLOWERING LOCUS T, florigen