Abstract
Hd6 gene encodes a casein kinaseII (CK II) alpha subunit and suppresses flowering in long-days (LD) in rice, a short-day plant. Since CKII has been shown to be a key component of the circadian clocks in several model organisms, we analyzed mRNA expression pattern of circadian clock-related genes of rice, such as OsLHY, OsGI and Hd1, between Nipponbare and a near isogenic line [NIL(Hd6)], which have a functional Hd6 allele. However, we did not detect any significant differences in those mRNA patterns between them. In addition, rhythmic CAB1R::LUC expression was not affected in rice seedlings by Hd6. These suggest that the floral inhibition by Hd6 is not mediated by phase shifts of circadian clocks. Furthermore, FT-like floral inducer genes are repressed by Hd6 at 50-days ~ 71-days old plants grown under LD, but OsGI and Hd1mRNA are not. Therefore, Hd6 controls flowering in rice by repressing FT-like genes.
