Abstract：
Phenylpropanoid metabolism plays an important role in cantaloupe ripening and senescence, but the mechanism of ozone regulation on phenylpropanoid metabolism remains unclear. This study investigated how ozone treatment modulates the levels of secondary metabolites associated with phenylpropanoid metabolism, the related enzyme activities, and gene expression in cantaloupe. Treating cantaloupes with 15 mg/m3 of ozone after precooling can help maintain postharvest hardness. This treatment also enhances the production and accumulation of secondary metabolites, such as total phenols, flavonoids, and lignin. These metabolites are essential components of the phenylpropanoid metabolic pathway, activating enzymes like phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4CL, chalcone synthase, and chalcone isomerase. The results of the transcriptional expression patterns showed that differential gene expression related to phenylpropanoid metabolism in the peel of ozone-treated cantaloupes was primarily observed during the middle and late storage stages. In contrast, the pulp exhibited significant differential gene expression mainly during the early storage stage. Furthermore, it was observed that the level of gene expression in the peel was generally higher than that in the pulp. The correlation between the relative amount of gene changes in cantaloupe, activity of selected enzymes, and concentration of secondary metabolites could be accompanied by positive regulation of the phenylpropanoid metabolic pathway. Therefore, ozone stress induction positively enhances the biosynthesis of flavonoids in cantaloupes, leading to an increased accumulation of secondary metabolites. Additionally, it also improves the postharvest storage quality of cantaloupes.
摘要：
苯丙素代谢在哈密瓜成熟和衰老中起重要作用，但臭氧对苯丙素代谢的调控机制尚不清楚。这项研究调查了臭氧处理如何调节与苯丙素代谢相关的次级代谢产物的水平，相关的酶活性，和哈密瓜中的基因表达。预冷后用15mg/m3的臭氧处理哈密瓜有助于保持采后硬度。这种处理还增强了次生代谢产物的产生和积累，如总酚，黄酮类化合物，和木质素。这些代谢物是苯丙素代谢途径的重要组成部分，激活酶如苯丙氨酸氨裂解酶，肉桂酸4-羟化酶，4CL,查尔酮合成酶，和查尔酮异构酶。转录表达模式的结果表明，臭氧处理的哈密瓜果皮中与苯丙素代谢相关的差异基因表达主要在贮藏中后期观察到。相比之下,果肉主要在贮藏早期表现出显著的差异基因表达。此外，观察到果皮中的基因表达水平通常高于果肉中的基因表达水平。哈密瓜基因变化的相对数量之间的相关性，选定酶的活性，和次级代谢产物的浓度可以伴随着苯丙烷代谢途径的正向调节。因此,臭氧胁迫诱导积极增强哈密瓜中黄酮类化合物的生物合成，导致次生代谢产物积累增加。此外,还提高了哈密瓜的采后贮藏质量。
