Overexpression of Rhodiola crenulata glutathione peroxidase 5 increases cold tolerance and enhances the pharmaceutical value of the hairy roots

Rhodiola crenulata , a plant of great medicinal value found in cold high -altitude regions, has been excessively exploited due to the difficulty in cultivation. Understanding Rhodiola crenulata's adaptation mechanisms to cold environment can provide a theoretical basis for artificial breeding. Glutathione peroxidases (GPXs), critical enzymes found in plants, play essential roles in antioxidant defense through the ascorbate - glutathione cycle. However, it is unknown whether GPX5 contributes to Rhodiola crenulata ' s cold tolerance. In this study, we investigated the role of GPX5 in Rhodiola crenulata ' s cold tolerance mechanisms. By overexpressing Rhodiola crenulata GPX5 ( RcGPX5 ) in yeast and Arabidopsis thaliana , we observed down -regulation of Arabidopsis thaliana GPX5 ( AtGPX5 ) and increased cold tolerance in both organisms. Furthermore, the levels of antioxidants and enzyme activities in the ascorbate - glutathione cycle were elevated, and cold -responsive genes such as AtCBFs and AtCORs were induced. Additionally, RcGPX5 overexpressing lines showed insensitivity to exogenous abscisic acid (ABA), suggesting a negative regulation of the ABA pathway by RcGPX5 . RcGPX5 also promoted the expression of several thioredoxin genes in Arabidopsis and interacted with two endogenous genes of Rhodiola crenulata , RcTrx2-3 and RcTrxo1 , located in mitochondria and chloroplasts. These findings suggest a significantly different model in Rhodiola crenulata compared to Arabidopsis thaliana , highlighting a complex network involving the function of RcGPX5 . Moreover, overexpressing RcGPX5 in Rhodiola crenulata hairy roots positively influenced the salidroside synthesis pathway, enhancing its pharmaceutical value for doxorubicin-induced cardiotoxicity. These results suggested that RcGPX5 might be a key component for Rhodiola crenulata to adapt to cold stress and overexpressing RcGPX5 could enhance the pharmaceutical value of the hairy roots.