Dr Stephen Jackson
Flowering time mutants
Several T-DNA tagged Arabidopsis mutants have been isolated from a screen looking for early and late flowering mutants in short days (SD), these mutants are being characterised further in our research group.
dnf mutant (left) and WT (right) growing in short days
One example is the day neutral flowering (dnf) mutant shown above, which is virtually aphotoperiodic as it flowers at the same time in SD as it does in long days (LD) (see fig.1), thus in this mutant there is no inhibitory effect of SD on flowering. We showed that the DNF gene encoded an E3 ligase that regulated the expression of the key floral regulator CONSTANS gene and thus flowering time. We have shown that the DNF gene is expressed at a specific time during the early part of the day and its role is to repress the expression of CONSTANS in SD. In the dnf mutant where there is no longer repression of CONSTANS expression, flowering can be induced in short photoperiods, and this is reflected in the altered critical photoperiod of the dnf mutant (fig.2).
For further information see Morris, K., Thornber, S., Codrai, L., Richardson, C., Craig, A., Sadanandom, A., Thomas, B. and S. Jackson (2010). DAY NEUTRAL FLOWERING represses CONSTANS to prevent Arabidopsis flowering early in short days. Plant Cell 22:1-11.