Abstract: A new plant gene was identified by randomly cloning and sequencing from cDNA library constructed from Chimonanthus praecox flowers. The gene has an open reading frame（ORF）of 384 bp encoding a putative 127aa-polypeptide，and its mature form contains a conservative YIXY domain，a YXRGC domain and four cysteine residues characteristic to the RALF gene. This gene was thereafter named as CpRALF（GenBank accession No. JQ217379）. Real-time fluorescence quantitative PCR demonstrated that steady-state expression of CpRALF was higher in root and blooming flower compared to that in stem and leaf. And there is a lower expression level in cotyledon and tender leaves. During the lifespan，the expression of CpRALF was more abundant in bud stage and wither period than in other periods. The expression of CpRALF was inducible under various abiotic stresses including high temperature，salinity and heavy metals，while low temperature could inhibit the expression of CpRALF. The transcriptional responses of CpRALF subject to salinity and heavy metal treatments were more sensitive and severe than other treatments. In conclusion，we propose that the CpRALF gene may play a significant role in Chimonanthus praecox flower development and abiotic stress responses.

Key words: Chimonanthus praecox, rapid alkalinization factor（RALF）, gene clone, expression analysis