Inhibition of downy blight and enhancement of resistance in litchi fruit by postharvest application of melatonin

• Published in: Food chemistry 2021-06, Vol.347, p.129009-129009, Article 129009
• Main Authors: Zhang, Zhengke, Wang, Tian, Liu, Gangshuai, Hu, Meijiao, Yun, Ze, Duan, Xuewu, Cai, Kun, Jiang, Guoxiang
• Format: Article
• Language: English
• Subjects: Energy Metabolism; Flavonoids - analysis; Flavonoids - metabolism; Fruit - chemistry; Induced resistance; Litchi - chemistry; Litchi - drug effects; Litchi - metabolism; Litchi - microbiology; Melatonin - chemistry; Melatonin - pharmacology; Mycoses - drug therapy; Peronophythora litchii; Phenols - analysis; Phenols - metabolism; Phenylalanine Ammonia-Lyase - analysis; Phenylalanine Ammonia-Lyase - metabolism; Phenylpropanoid pathway; Plant Diseases; Postharvest disease; Trans-Cinnamate 4-Monooxygenase - analysis; Trans-Cinnamate 4-Monooxygenase - metabolism
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2021.129009

•Melatonin inhibited litchi downy blight caused by Peronophythora litchii in litchis.•Melatonin activated phenylpropanoid and pentose phosphate pathways in litchis.•Melatonin maintained higher energy status by promoting energy metabolism in litchis.•The metabolic changes induced by melatonin contributed to enhanced fruit resistance. Litchis are tasty fruit with economic importance. However, the extreme susceptibility of harvested litchis to litchi downy blight caused by Peronophythora litchii leads to compromised quality. This study aimed to study the effects of melatonin on postharvest resistance to P. litchii in ‘Feizixiao’ litchis. Results showed that melatonin restricted lesion expansion in litchis after P. litchi inoculation. Melatonin enhanced the activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase and 4-hydroxycinnamate CoA ligase while promoting the accumulations of phenolics and flavonoids. Nicotinamide adenine dinucleotide phosphate content and glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase activities were higher in treated fruit than control fruit. Higher energy status along with elevated H+-ATPase, Ca2+-ATPase, succinate dehydrogenase and cytochrome C oxidase activities were observed in treated fruit. Ultrastructural observation showed reduced damage in mitochondria in treated fruit. The results suggest that melatonin induced resistance in litchis by modulating the phenylpropanoid and pentose phosphate pathways as well as energy metabolism. .