ASHS 2025 Conference

The incidence of necrotic peel disorders during cold storage is a severe CI symptom observed in hardy kiwifruit, impacting fruit visual quality. This study focuses on understanding the mechanisms of necrotic peel disorder in ‘Daebo’ hardy kiwifruit cultivar during cold storage. This research aimed to investigate the effects of different soluble solids content (SSC)-based fruit maturity at harvest on the severity of peel disorder after storage and to present the associated biochemical alteration using integrated transcriptomic, antioxidant, and lipidomic analyses. The fruit of ‘Daebo’ hardy kiwifruit cultivar harvested at various SSC levels, including 5.5%, 6.1%, and 7.2%, were cold-stored for upto four weeks. Fruit harvested at 5.5% SSC exhibited the highest severity of necrotic peel disorder, accompanied by significant weight loss and elevated reactive oxygen species (ROS) levels. The enhanced activities of antioxidant scavenging enzymes, such as superoxide dismutase and ascorbate peroxidase, were observed, indicating the response of fruit to oxidative stress. However, lower enzymatic activities of dehydroascorbate reductase and glutathione reductase were insufficient to restore the ascorbic acid-glutathione cycle. In contrast, the 7.2% SSC fruit contained higher concentrations of phenolic compounds, suggesting their role as natural antioxidants in mitigating oxidative damage. Additionally, lipid analysis revealed increased levels of phosphatidylcholine and fatty acids during fruit maturation, which are crucial for membrane stability. Notably, the differences in phosphatidic acid concentrations between SSC levels indicated its potential role in ROS scavenging. Overall, this study elucidates the biochemical mechanisms contributing to necrotic peel disorder in hardy kiwifruit during cold storage, highlighting the importance of SSC at harvest in managing fruit quality. These findings can comprehensively understand necrotic peel disorder and fruit maturity in hardy kiwifruit.