Multi-walled carbon nanotubes prevent high temperature-induced damage by activating the ascorbate-glutathione cycle in Paeonia ostii T. Hong et J. X. Zhang

Multi-walled carbon nanotubes (MWCNTs) are considered important nanomaterials with rapidly growing applications. They are inevitably released into the environment, which has attracted considerable attention for their potential threats to ecosystems. In this study, Paeonia ostii T. Hong et J. X. Zhang was exposed to MWCNTs at different concentrations under high temperature. The results showed that high temperature-induced P. ostii damage was prevented by MWCNTs, and 200 mg/L was the most effective concentration. First, MWCNTs prevented increases in reactive oxygen species, relative electrical conductivity and free proline content, and reduced decreases in SPAD, chlorophyll and carotenoid contents. Moreover, the ascorbate-glutathione (ASA-GSH) cycle was activated in response to the MWCNTs treatments, whereas the superoxide dismutase and catalase activities were inhibited. And the MWCNTs treatments also resulted in higher photosynthesis and more intact anatomical structures. Furthermore, the metabolome also confirmed that the ASA-GSH cycle played a critical role in P. ostii high-temperature tolerance, and other biological processes also responded to the MWCNTs treatments. Additionally, the genes involved in the P. ostii ASA-GSH cycle were highly expressed in response to the MWCNTs treatments. These results elucidated the beneficial role of MWCNTs in P. ostii growth under high temperature