Effects of nitric oxide on the alleviation of postharvest disease induced by Penicillium italicum in navel orange fruits

Abstract

SummaryThe present study evaluated the effects of 15 μL L‐1 nitric oxide (NO) on the fruit defence response of ‘Newhall’ navel orange. The decay rate of NO‐treated navel orange fruits was significantly lower than that of control fruits during storage at 20 °C storage (P < 0.05). Treatment with NO suppressed the increase in disease incidence and lesion area in orange fruits inoculated with Penicillium italicum (P. italicum); significantly increased the activities of phenolic metabolism‐associated enzymes and pathogenesis‐related (PR) proteins, including polyphenoloxidase (PPO), phenylalanine ammonia‐lyase (PAL), β‐1,3‐glucanase (GLU) and chitinase (CHT); and enhanced the activities of key enzymes, including 4‐coumarate: CoA ligase (4CL), cinnamate‐4‐hydroxylase (C4H) and chalcone isomerase (CHI) in the phenylpropanoid pathway. The contents of total phenolics, flavonoids and lignin were also higher in NO‐treated fruits than in control fruits. The findings suggest that exogenous NO could induce disease resistance against P. italicum in navel orange fruits.