Overexpression of PpmTERF18 enhances the antioxidant capacity of peach fruit to alleviate oxidative damage

Mitochondrial transcription termination factors (mTERFs) are involved in the replication, transcription, and translation of mitochondrial genes and have essential biological functions in plant development and stress response. However, the functions and regulatory mechanisms of many mTERF family members are still unclear. In this study, the cDNA coding region sequence of the mitochondrial transcription termination factor 18 (mTERF18) gene in peaches was cloned, the peaches mTERF18 protein was predicted and analyzed, and the gene was conducted transient transformation in tomato and peach to investigate the roles of PpmTERF18 in fruit mitochondrial function and antioxidant capacity. The results showed that the PpmTERF18 gene encoded 573 amino acids, mainly composed of α-helix and β-sheet, an alkaline-labile protein in mitochondria. The results showed that overexpression of PpmTERF18 in tomatoes delayed the color change, and overexpression of PpmTERF18 in peach fruit could maintain the quality of peach fruit. Overexpression of PpmTERF18 increased the activities and the expression levels of mitochondrial antioxidant-related genes, reduced mitochondrial oxygen consumption and cytochrome c content, inhibited the opening of mitochondrial permeability transition pore (MPTP), and maintained mitochondrial functions in tomato and peach fruit. After cold stress treatment, overexpression of PpmTERF18 increased the proline content and phenylalanine ammonia-lyase (PAL) activity in peach fruit, decreased the content of malondialdehyde (MDA), improved the antioxidant capacity of the fruit, and maintained the quality of the fruit.