UV-C delays senescence in 'Lingwu long' jujube fruit by regulating ROS and phenylpropanoid metabolism.

Ultraviolet (UV–C), a no residual environmentally friendly physical treatment, plays an important role in delaying the senescence in fruit. In this study, 'Lingwu long' jujubes were treated with UV-C (5 kJ m−2) to investigate the impacts of cell wall degrading enzymes (CWDEs) activities, reactive oxygen species (ROS) metabolism, and phenylpropanoid metabolism under storage at 4 ± 1 °C for 30 d. UV-C treatment reduced respiration rate and decay index. Treated fruit exhibited lower polygalacturonase (PG), pectinate lyases (PL), cellulase (Cel), and β-galactosidase (β-gal) activities which ultimately delayed the reduction of firmness. UV-C treatment increased hydrogen peroxide (H 2 O 2), free radical scavenging ability, and superoxide dismutase (SOD) and catalase (CAT) activities, reduced superoxide anion (O 2 −) and malondialdehyde (MDA) content. In addition, ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) activities were activated by UV-C treatment, leading to glutathione (GSH) and ascorbic acid (AsA) increased. Besides, phenolic compounds of jujube fruit treated with UV-C were also increased, which might be due to the enhanced phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL) activities. In conclusion, UV-C was recommended for improving overall quality and alleviating senescence in jujube fruit. • UV-C delayed the softening rate in jujube fruit. • UV-C inhibited membrane lipid peroxidation in jujube fruit. • UV-C improved the reactive oxygen species scavenging ability in jujube fruit. • UV-C activated the phenylpropane metabolic pathway. • UV-C treatment showed great potential to delay senescence in jujube fruit. [ABSTRACT FROM AUTHOR]