Ectopic expression of a Penicillium oxalicum cyclophilin gene in Arabidopsis thaliana imparts tolerance to cold stress.

Cyclophilins are ubiquitous proteins that are essential for cis-trans isomerisation of peptide bonds preceding the proline residue. Apart from catalysing the cis-trans isomerization, these proteins are also implicated in diverse cellular functions. We investigated the role of a cyclophilin gene PoxCYP62-2, isolated from a halotolerant strain of Penicillium oxalicum, in abiotic stress tolerance of plants. Ectopic expression of PoxCYP62-2 gene in transgenic Arabidopsis thaliana plants conferred tolerance to cold stress. The transgenic plants exhibited higher rosette fresh and dry mass, lower MDA content, and increase in chlorophyll and proline content. Metabolite profiling revealed cold-induced increase in several metabolites that are known to enhance cold tolerance of plants in transgenic plants. Confocal microscopy suggested that PoxCYP62-2 protein was localized to nucleus in agroinfiltrated leaves of Nicotiana benthamiana. These findings suggests that PoxCYP62-2 gene is a potential candidate for enhancing cold stress-tolerance of crop plants.