Abstract: The LEAFY gene plays a key role in the regulation network of plant flower development，
and its homologous gene named AcLFY（GenBank accession No.：JX275962）was isolated from onion
（Allium cepa L.‘1007’）using homology gene cloning and RACE-PCR. Sequence analysis showed that
the AcLFY gene has a 1 119 bp open reading frame（ORF）encoding 372 amino acids. The amino acid
sequence contains a 5′-N praline-rich region，a leucine zipper and a central acidic region，which are typical
structure features of LEAFY（FLO）family. Homology analysis showed that the deduced AcLFY protein is
highly homologous to other LEAFY proteins from different species，especially to the one from Narcissus
tazetta with approximately 70% identity. Phylogenetic tree analysis indicated that AcLFY is more related to
LEAFY in monocotyledons than those in dicotyledonous plants. The real-time PCR results showed that the
AcLFY was detected during the whole period of bolting and flowering in onion，and it had a high
transcription level in inflorescence meristem at the beginning of the bolting but nearly no transcription in
floral organ. After the development of floral organ，the AcLFY gene mainly expressed in leaves

Key words: Allium cepa, AcLFY, bolting and flowering, gene cloning, expression analysis