Abstract
Arabidopsis terminal flower2 (tfl2) mutant shows an early-flowering phenotype in a day-length independent manner. Molecular cloning has revealed that TFL2 encodes a nuclear protein homologous to HP1, which is known to mediate heterochromatin formation and transcriptional repression of several euchromatic genes. We have shown that upregulation of a flowering gene FT causes the early flowering of tfl2, suggesting that TFL2 functions to regulate flowering time by repressing FT expression during non-inductive conditions. By using FT promoter::GUS transgenic plants, we found that the expression patterns of FT in tfl2 were less affected. Thus it is suggested that TFL2 functions to maintain low levels of FT expression during Arabidopsis development. It remains unclear, however, how the repression by TFL2 is cancelled when FT is activated. To address this question, we are now investigating the effect of TFL2 on FT activation by a direct transcriptional activator CONSTANS.
