Ozone gas induces plant defense enzymes and mitigates ethylene biosynthesis to control fruit rot disease and maintain harvested jackfruit quality

Fruit rot disease poses a significant problem in harvested jackfruit. In response to this, ozone treatment emerges as a potential approach for suppressing microbial infections, particularly fungal ones. This study investigated the effects of 325–350 ppm ozone treatment on disease severity and the activity of plant defense–related enzymes in jackfruit stored at 13 ˚C for 20 days, compared with untreated fruit (control). The results revealed that ozone treatment led to a 53.4 % reduction in disease severity and significantly enhanced the activities of plant defense enzymes, including phenylalanine ammonia-lyase (PAL), peroxidase (POD), chitinase (CHI), and β-1,3-glucanase (GLU), compared with the control group. Further, ozone treatment affected the physicochemical properties and quality of the fruit, suppressing ethylene production by inhibiting 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC synthase (ACS) and ACC oxidase (ACO) activities, as well as the respiration rate, which contributed to reduced fruit quality deterioration. Ozone treatment preserved color, total soluble solids (TSS), and fruit firmness. Additionally, it increased total phenolic content, ascorbic acid levels, and antioxidant activity (2,2- diphenyl-1-picrylhydrazyl (DPPH) inhibition). These findings suggest that ozone treatment is an effective and safe method for controlling fruit rot disease, achieved by inducing plant defense–related enzymes and maintaining the quality of harvested jackfruit by mitigating ethylene biosynthesis enzymes.