Dear Editor,As one of the most important developmental traits,flowering time has been extensively investigated in the long-day plant Arabidopsis.Multiple factors are involved,including photoperiod and/or temperature (Amasino,2010).Flowering locus T (FT) is known to be an important integrator of different flowering pathways (Taoka et al.,2011).Genes of the CONSTANS (CO) family also play key roles in regulating flowering time.The CO protein consists of a zinc finger and a CCT domain shared by a group of plant-specific transcription factors that regulate photoperiodic flowering response and circadian rhythms in Arabidopsis.In the case of short-day plants such as rice,previous studies have also revealed a number of genes that control heading date,such as the CO ortholog Heading date 1 (Hdl) and,at its downstream,Heading date 3a (Hd3a),an ortholog of FT (Kojima et al.,2002;Komiya et al.,2008).Although the main photoperiodic flowering regulators are highly conserved between Arabidopsis and rice,there are genes that act differently relating to the daylength property of rice,such as Early heading datel (Ehdl),Indeterminate1 (OslD1),the MADS-box gene OsMADS51 (Doiet al.,2004;Kim et al.,2007;Park et al.,2008),and Ghd7 (Xue et al.,2008).