Expression of a Solanum tuberosum cyclophilin gene is regulated by fungal infection and abiotic stress conditions

Abstract

Cyclophilins (CyPs) are ubiquitous proteins with an intrinsic enzymatic activity of peptidyl-prolyl cis- trans isomerase that catalyzes the rotation of X-Pro peptide bonds. These enzymes are believed to play a role in the folding of certain proteins. In addition, CyPs might be important in signal transduction processes. A cDNA library was prepared from potato ( Solanum tuberosusm) tubers infected with the fungus Fusarium solani f. sp eumartii. Using a PCR-amplified subtracted cDNA probe, a clone encoding a cytosolic form of CyP, called StCyP ( S̱ olanum ṯ uberosum CyP), was isolated. Except in tubers, StCyP is expressed at high levels in tissues of healthy potato plants. Northern blot analyses revealed that both wounding and fungal infection increased the level of StCyP mRNA in tubers. However, whereas wounding causes a transient accumulation of StCyP mRNA, fungal infection results in a maintained accumulation of this transcript. StCyP mRNA accumulation is also stimulated by the application of absicic acid (ABA) and methyl jasmonate (MeJA) in tubers. Treatment with fungal elicitor or salicilic acid (SA) has no effect on the level of StCyP mRNA accumulation. Together these results indicate that the observed accumulation of StCyP mRNAs in fungal-infected potato tubers might be a response to the wound produced by the penetration and colonization of the tissue by the pathogen. Furthermore, accumulation of StCyP transcripts was also detected when the potato tubers were exposed to heat-shock treatment. These findings support a role for cyclophilins in the plant response to environmental stresses.