Dynamic changes in ROS-antioxidant-metabolite network in dragon fruit infected with Neoscytalidium dimidiatum

This study investigates the effects of Neoscytalidium dimidiatum (N. dimidiatum) infection on the postharvest quality of dragon fruit. Infection accelerated fruit softening, decay, and weight loss, while increasing the respiration rate and total acid (TA) content, and decreasing soluble solids (TSS) content. Pathogen infection triggered a rapid reactive oxygen species (ROS) burst, leading to oxidative stress, with O₂ ^- and malondialdehyde (MDA) levels 2.11 and 1.58 fold higher than those of the controls, respectively. Antioxidant enzymes (SOD, CAT, POD, APX) were initially activated (0-2 days) but declined sharply later (6-10 days), resulting in increased ROS accumulation and decreased disease resistance. GC-MS analysis identified 87 metabolites (55 primary metabolites and 32 VOCs), revealing an increase in carbohydrates (glycerol, sorbitol) and a decrease in amino acids, organic acids, and heterocyclic compounds. These findings highlight a ROS-antioxidant-metabolite network underlying disease resistance, providing valuable insights for sustainable postharvest management.