Cyclophilins were first identified as intracellular targets of the immunosuppressant cyclosporin A. Using a cDNA library constructed from petunia petal protoplast culture cells, we have isolated cDNAs corresponding to three different cyclophilins and the corresponding genes have been designated PhCyP1, PhCyP2 and PhCyP3 (Petunia hybrida Cyclophilin). Here we report expression patterns of these three genes by Northern analysis and by RT-PCR. PhCyP1 and PhCyP3 transcripts were expressed in all plant tissues (root, stem, leaf, and flower) examined, although PhCyP1 showed much stronger expression than PhCyP3. Examination of expression patterns in whole plants showed that PhCyP transcripts were predominantly expressed at the early stage of floral development. The accumulation of PhCyP1 mRNA in petal protoplast cultures increased after 1 day and reached a maximum level at 4 days of culture. These findings further suggest that cyclophilins might play a functional role in actively growing cells and plant growth.