Metabolic Profiling and Molecular Mechanisms Underlying Melatonin-Induced Secondary Metabolism of Postharvest Goji Berry (Lycium barbarum L.)

Junjie Wang; Huaiyu Zhang; Jie Hou; En Yang; Lunaike Zhao; Yueli Zhou; Wenping Ma; Danmei Ma; Jiayi Li

doi:10.3390/foods12234326

Metabolic Profiling and Molecular Mechanisms Underlying Melatonin-Induced Secondary Metabolism of Postharvest Goji Berry (Lycium barbarum L.)

Foods. 2023 Nov 29;12(23):4326. doi: 10.3390/foods12234326.

Authors

Junjie Wang¹, Huaiyu Zhang^{1

2}, Jie Hou¹, En Yang¹, Lunaike Zhao¹, Yueli Zhou¹, Wenping Ma¹, Danmei Ma¹, Jiayi Li¹

Affiliations

¹ Key Laboratory of Storage and Processing of Plant Agro-Products, School of Biological Science and Engineering, North Minzu University, Yinchuan 750021, China.
² School of Food and Biological Engineering, Hefei University of Technology, Hefei 230601, China.

Abstract

Postharvest decay of goji berries, mainly caused by Alternaria alternata, results in significant economic losses. To investigate the effects of melatonin (MLT) on resistance to Alternaria rot in goji berries, the fruits were immersed in the MLT solutions with varying concentrations (0, 25, 50, and 75 μmol L^-1) and then inoculated with A. alternata. The results showed that the fruits treated with 50 μmol L^-1 MLT exhibited the lowest disease incidence and least lesion diameter. Meanwhile, endogenous MLT in the fruits treated with 50 μmol L^-1 MLT showed higher levels than in the control fruits during storage at 4 ± 0.5 °C. Further, the enzymatic activities and expressions of genes encoding peroxidase, phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4-coumarate-CoA ligase, chalcone synthase, chalcone isomerase, and cinnamyl alcohol dehydrogenase were induced in the treated fruit during storage. UPLC-ESI-MS/MS revealed that secondary metabolites in the fruits on day 0, in order of highest to lowest levels, were rutin, p-coumaric acid, chlorogenic acid, ferulic acid, caffeic acid, naringenin, quercetin, kaempferol, and protocatechuic acid. MLT-treated fruits exhibited higher levels of secondary metabolites than the control. In conclusion, MLT treatment contributed to controlling the postharvest decay of goji fruit during storage by boosting endogenous MLT levels, thus activating the antioxidant system and secondary metabolism.

Keywords: Lycium barbarum L.; antioxidant enzyme; melatonin; phenylpropanoid pathway; secondary products.

Grants and funding

This research was funded by the Key Program of Natural Scientific Foundation of Ningxia (Grant No. 2020AAC02030 and 2022AAC02047), the Natural Scientific Foundation of Ningxia (Grant No. 2022AAC03229), and the School-level Key Program of North Minzu University (Grant No. 2021KJCX08).