关键词: 铁皮石斛, 亲环蛋白, DoCyP, qRT-PCR, 低温胁迫

Abstract: The cyclophilin gene（DoCyP）in Dendrobium officinale was cloned by RT-PCR. The full-length of DoCyP was 522 bp，encoding 173 amino acids. Bioinformatics predicted that DoCyP is a stable hydrophilic protein with a relative molecular mass of 18.25 kD，containing a peptide-prolyl cis-transisomerase domain. The theoretical isoelectric point of DoCyP is 8.72，and no transmembrane domain. SOPMA predicted that the secondary structure of DoCyP primarily consists of random coils and extended chains. The phylogenetic tree indicated that DoCyP of D. officinale has a relatively close genetic relationship with Apostasia shenzhenica CyP. qRT-PCR results revealed that DoCyP was constitutively expressed in different tissues of D. officinale. The relative expression of DoCyP was higher in roots，compared to leaves and stems. Under low-temperature（4 ℃）stress，the expression of DoCyP in different D. officinale tissues showed different trends. Compared with normal expression level，DoCyP expression after treatment with 4 ℃ for 12 h was up-regulated in roots，while down-regulated in stems and leaves，suggesting that DoCyP may take part in response to low temperature stress in D. officinale.

Key words: Dendrobium officinale, cyclophilin, DoCyP, qRT-PCR, low temperature stress