Late-flowering genes interact with early-flowering genes to regulate flowering time in Arabidopsis thaliana.

To investigate the genetic mechanisms regulating the transition from the vegetative to reproductive growth in Arabidopsis, double mutants between three different early-flowering mutants, early flowering 1-1, 2-1, 3-1, (elf 1-1, 2-1, 3-1) and five different late-flowering mutants, gi-1, ft-1, fwa-1, ld-1, and fca-9, were constructed and phenotypes analyzed. Double mutants in all combinations displayed the late-flowering phenotypes which resembled their respective late-flowering parents in both flowering time and the number of vegetative leaves produced. The results indicate that five late-flowering mutants are epistatic to all three early-flowering mutants tested here. This epistatic relationship suggests that ELF1, ELF2, and ELF3 genes function upstream of these five late-flowering genes no matter if they are functioning in autonomous or photoperiod pathways. These three early-flowering genes may negatively modify the activity of most late-flowering genes to influence the time of the vegetative-to-reproductive transition in Arabidopsis.