Near-freezing temperature storage preserves prune quality by modulating respiratory and energy metabolism

Maintaining energy homeostasis is essential for preserving postharvest fruit quality. This study investigated the effects of near-freezing temperature (NFT, −1 ± 0.5 °C) storage on respiratory and energy metabolism in prunes (Prunus domestica L.) compared with conventional low-temperature (LT, 4 ± 0.5 °C) storage. Over 42 d, NFT-treated prunes exhibited significantly lower weight loss, firmer texture, and delayed color changes relative to LT samples. NFT suppressed respiration rate and ethylene production, reduced cell membrane permeability and malondialdehyde accumulation, and better preserved mitochondrial structure. At the metabolic level, NFT maintained higher adenosine triphosphate (ATP) and energy charge, enhanced nicotinamide adenine dinucleotide phosphate (NADPH) accumulation, and delayed the decline of nicotinamide adenine dinucleotide kinase activity. NFT downregulated hexokinase and phosphoglucose isomerase, conserving ATP and redirecting glucose-6-phosphate flux toward the pentose phosphate pathway, thereby promoting redox balance. The expression of pyruvate kinase was upregulated under NFT, facilitating pyruvate entry into the tricarboxylic acid cycle while suppressing pyruvate decarboxylase and alcohol dehydrogenase expression, thus limiting anaerobic fermentation. The activities of key mitochondrial enzymes, including succinate dehydrogenase, cytochrome c oxidase, and ATPase, were consistently higher under NFT, supporting efficient oxidative phosphorylation. NFT modulated respiratory and energy metabolism to maintain energy stability, delay senescence, and extend storage life in prunes. These findings highlight NFT as an effective strategy to preserve postharvest quality and provide mechanistic insights into temperature-mediated regulation of fruit metabolism.