AUTHOR=Qu Guangfan , Wu Wenneng , Ba Liangjie , Ma Chao , Ji Ning , Cao Sen 

TITLE=Melatonin Enhances the Postharvest Disease Resistance of Blueberries Fruit by Modulating the Jasmonic Acid Signaling Pathway and Phenylpropanoid Metabolites

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.957581

DOI=10.3389/fchem.2022.957581

ISSN=2296-2646

ABSTRACT=<p>In this study, to investigate the physiological and molecular mechanisms of melatonin inhibiting the postharvest rot of blueberry fruits, blueberry fruits were dipped in 0.3 mmol L<sup>−1</sup> melatonin solution for 3 min and stored at 0°C for 80 days. The results indicated that melatonin did not significantly (<italic>p</italic> &gt; 0.05) inhibit the mycelial growth or spore germination of <italic>Alternaria alternata</italic>, <italic>Botrytis cinerea</italic>, and <italic>Colletotrichum gloeosporioides</italic>. In addition, an <italic>in vivo</italic> study revealed that melatonin treatment increased the enzymatic activities of phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), polyphenol oxidase (PPO), and peroxidase (POD) in fruits. Furthermore, genes related to jasmonic acid synthesis were upregulated (<italic>VaLOX</italic>, <italic>VaAOS</italic>, and <italic>VaAOC</italic>), as were those related to pathogenesis-related proteins (<italic>VaGLU</italic> and <italic>VaCHT</italic>) and phenylpropane metabolism (<italic>VaPAL</italic>, <italic>VaC4H</italic>, <italic>Va4CL</italic>, <italic>VaCAD</italic>, <italic>VaPPO</italic>, and <italic>VaPOD</italic>), which promoted the accumulation of total phenols, flavonoids, anthocyanins, and lignin in the fruits. These results suggest that melatonin enhances the postharvest disease resistance of blueberry fruits by mediating the jasmonic acid signaling pathway and the phenylpropane pathway.</p>