Cyclophilin Atroc1(S58f) Confers Arabidopsis Cold Tolerance By Modulating Jasmonic Acid Signaling And Antioxidant Metabolism

Cyclophilins (CYPs), a class of proteins with a conserved peptidyl-prolyl cis-trans isomerase domain, are widely involved in the regulation of plant growth and development, as well as in the response to abiotic stresses including cold. In our previous study, we identified an Arabidopsis gain-of-function mutant ROC1(S)(58F) with enhanced cold-tolerance and enhanced expression of jasmonic acid (JA) and oxidative stress responsive genes. Here, we show the underlying molecular mechanisms for the improved cold tolerance observed in the ROC1(S)(58F) mutant. Compared to the WT, the ROC1(S)(58F) mutant showed an increased survival rates and a reduced level of electrolyte leakage and endogenous JA content under the freezing treatment. Correspondingly, the JA biosynthesis genes (AtAOC1 and AtOPR3) and signaling genes (AtJAZ5, AtJAZ10 and AtMYB15) are down-regulated in the ROC1(S)(58F) mutant compared with the WT. Moreover, both the transcripts and activities of the ROS-scavenging enzymes (SOD/POD/MDHAR) increased in cold-stressed ROC1(S)(58F) mutant, which might mitigate the ROS-induced oxidative stress and contribute to the mutant freezing tolerance. Taken together, our findings indicate that AtROC1(S)(58F) confers Arabidopsis freezing tolerance by modulating JA signaling and antioxidant metabolism jointly. This research thus provides a molecular mechanism for AtROC1(S)(58F)-conferred freezing resistance in Arabidopsis and offers guidance for crop breeding towards an improved cold tolerance.