Apyrase MaAPY2 regulates the chilling tolerance of banana fruit as a negative modulator

Abstract

Chilling injury (CI) affects greatly postharvest quality of banana fruit during storage at < 13 °C. Apyrases (APYs) as a class of nucleoside triphosphate diphosphohydrolases (NTPDases) play a crucial role in regulating energy levels under various stress conditions. The potential effects of MaAPY2 on CI in banana fruit stored for 6 d at 6 °C involved in the regulation of antioxidant ability and energy status were investigated. Ultrastructural observation revealed more severe mitochondrial structures in the transient overexpressed MaAPY2 (OE-MaAPY2) fruit. Furthermore, enhanced generation of reactive oxygen species, in association with the accelerated CI symptoms in the OE-MaAPY2 fruit under cold stress condition was observed, with low activities of antioxidant enzymes, including superoxide dismutase, catalase, and peroxidase, accompanied by a high activity of polyphenol oxidase. Transcriptomic analysis was performed to uncover the variations of transcriptional levels in banana fruit during CI development. Overall, these results implied that MaAPY2 to serve as a negative modulator could reinforce CI symptom in banana fruit by triggering oxidative stress and damaging mitochondrial integrity, which provided new insights on the regulatory CI mechanism of banana fruit during low-temperature storage.