The abundance of a single domain cyclophilin in Solanaceae is regulated as a function of organ type and high temperature and not by other environmental constraints.

The abundance of a single domain cyclophilin (CyP), designated as SsCyP, was investigated in Solanum sogarandinum and Solanum tuberosum plants during development and in response to various environmental constraints. We show that under control conditions, SsCyP is distributed throughout the plant but in an organ-specific manner. In both Solanum species, the highest protein levels are observed in transporting organs and in tubers, and substantial amounts are noticed in open flowers and in stamens. We also show that the SsCyP abundance in leaves strongly decreases with age. In in vitro-grown plantlets of S. sogarandinum, the SsCyP gene is induced by low temperature at the transcript level but not at the protein level, indicating that post-transcriptional mechanisms control SsCyP expression under cold conditions. In in vivo-grown Solanum plants, the organ-dependent SsCyP protein distribution and abundance are not modified by cold, drought, salinity and photooxidative treatments. In contrast, the protein abundance substantially decreases in all organs of Solanum plants subjected to heat shock. We conclude that the SsCyP protein acts mainly during development and does not belong to the group of stress-induced CyPs.