Photosensitization of riboflavin reduces the susceptibility to gray mold in postharvest kiwifruit

Kiwifruits are vulnerable to gray mold, and although the beneficial impacts of riboflavin on plant immunity have been acknowledged, there is a limited exploration into the influence of riboflavin photosensitization on gray mold. The impacts on gray mold susceptibility in postharvest kiwifruit were investigated at 25 °C for 8 d, and underlying mechanisms regarding oxidative stress, energy, jasmonic acid (JA), and sugars were evaluated. The morphological results showed that photosensitized riboflavin reduced the severity of gray mold. Biochemical and molecular assays indicated that riboflavin enhanced energy status, JA biosynthesis, glucose accumulation, and ameliorated oxidative stress, irrespective of photosensitization. Notably, photosensitized riboflavin exhibited three distinct effects: heightened impacts on oxidative stress and JA production; sustained electron transport chain activity without energy level increase; delayed early sucrose degradation. Collectively, these findings underscore the pivotal roles played by photosensitization-primed responses involving early stimulation of JA biosynthesis, and compromise of sucrose degradation, in enhancing resistance to gray mold in kiwifruit.