Autonomous pathway: FLK
The FLK gene is a recently identified autonomous pathway gene. It encodes a putative RNA binding protein and the mutant form has a late flowering phenotype in both long and short-day photoperiods. Vernalisation and the application of exogenous gibberellins are able to suppress the late flowering-time phenotype. Like other autonomous pathway genes, FLC mRNA levels increased in the flk mutant, whilst those of ft and soc1 were reduced (Lim et al., 2004) .
FLD encodes a protein that is a homologue of a protein found in mammalian histone deacetylase complexes (He et al., 2003) , emphasising the importance of histone modification in FLC regulation. Mutations in FLD result in delayed flowering, an increase in FLC expression and hyper acetylation of histones present in FLC chromatin. Therefore some genes assigned to the autonomous pathway encode negative regulators of FLC that act to cause histone deacetylation (He et al., 2003) .
Cloning of LUMINIDEPENDENS
LUMINIDEPENDENS (LD) was cloned through the use of T-DNA mutagenesis (Redei, 1962; Lee et al., 1994) . LD contains both a nucleic acid-binding homeodomain and an acidic rich carboxyl terminal, enriched with homopolymeric glutamine residues. These features are related to transcriptional activators of genes from Drosophila, Yeast and Antennapedia (van Nocker, 2001). Therefore, LD probably acts as a transcriptional regulator, the LD protein is localised to the nucleus, is expressed ubiquitously, and is involved in the regulation of the meristem identity gene LEAFY (LFY) (Aukerman et al., 1999) .
Therefore genes assigned to the autonomous pathway seem to represent protein complexes involved in RNA processing or histone modification and FLC expression seems particularly sensitive to disruption of these processes.
Forward to Vernalisation pathway