FRIGIDA

The majority of Arabidopsis accessions overwinter vegetatively. The winter habit can be mapped as a single gene trait to FRIGIDA. Allelic variation at FRIGIDA is the major determinant of flowering time variation.

We cloned FRIGIDA (Johanson et al, 2000) and found it encoded a novel protein with two coiled-coil domains (underlined in adjacent figure ). Analysis of the allelic variation at FRIGIDA showed many rapid cycling types contain FRIGIDA deletions eg Ler type deletion removes the first part of the coding region. So far we have characterised 20 independent loss-of-function FRIGIDA alleles (Shindo et al, 2005). In addition there are many amino acid polymorphisms, the functional significance of which is currently unknown.

A late-flowering plant with sectors of FRI-expressing cells (white) and GUS-expressing cells where FRI is absent (blue). Sectors were induced 8 days after pollination by a 37°C heatshock which activated the Cre-recombinase enzyme and led to FRI-expressing cells.

We are investigating when and where FRIGIDA is required in the plant using a sector analysis. So far this suggests that FRIGIDA is required during embryo development.

Current areas of activity:

1. Mis-expression of FRIGIDA to further define where FRIGIDA activity is required.
2. Anaysis of protein partners of FRIGIDA.
3. Role of FRIGIDA in 5' capping and chromatin regulation of FLC.