Abstract: Carrot（Daucus carota L.）is a biennial species and requires vernalization for flowering.
The premature bolting of carrot occurs in winter-spring plastic tunnel and spring cultivation，and results in
a complete loss of commercial value，but limited progress reported on the control of bolting and flowering
in carrot. Basis on the transcriptome sequences，carrot FLOWERING LOCUS C homologues（DcFLCs）
were screened. Cultivar‘Amsterdam’（Af）tolerance to premature bolting and wild sensitive species
‘Songzi’（Ws）were selected to study the relative expression of DcFLCs under cold and photoperiod
treatment examined by real-time qPCR. Three FLC homologues（DcFLC1，DcFLC2 and DcFLC3）were
annotated with complete ORFs，MADS-box and K-box conserved regions，which encoded 209，212 and
219 amino acids，respectively. Phylogenetic analysis showed that DcFLCs were clustered with other plants
FLC homologous. DcFLC1 and DcFLC2 were confirmed to express in all species by RT-PCR，but
DcFLC3 only in some. The relative expression of DcFLC1 and DcFLC3 were improved in Af young plants
and roots during vernalization，while DcFLC2 was only improved in roots but no significance in young plants. DcFLC1 were improved in Ws young plants but no significance in roots during vernalization，while
DcFLC2 in contrary. Both of the relative expression of DcFLC1 and DcFLC2 were improved in Af young
plants under continuous illumination，but different in Ws.

Key words: carrot, DcFLCs, low temperature, photoperiod, gene expression