Chrysanthemum ( Ramat) is a valuable crop mainly used for medicine, beverages and ornament. Enzymatic browning causes serious postharvest flower deterioration of chrysanthemum, but the mechanism remains unclear. To clarify the mechanism involved, the cellular ultrastructure, metabolites, browning products, and differentially expressed genes of chrysanthemum were studied systematically. During the browning process, cellular compartmentalization was severely disrupted and the contents of chlorogenic acid derivatives and flavonoid glycosides decreased significantly. A browning product with a dihydrobenzofuran skeleton was purified and identified for the first time from a simulated browning reaction of chlorogenic acid catalyzed by peroxidase. Moreover, six differentially expressed genes were for the first time identified to be involved in the regulation of oxidase by transcriptome and qPCR, and one of which (c76073_g1) was validated using in vitro enzyme activity determination. This research elucidates the inherent mechanism of enzymatic browning, provides a scientific explanation for the steam-treated processing of chrysanthemums and lays the foundation for the molecular breeding of anti-browning chrysanthemum varieties.

中文翻译：

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综合代谢表型和基因表达谱揭示了采后菊花的酶促褐变机制

菊花（Ramat）是一种名贵作物，主要用于药用、饮料和装饰品。酶促褐变导致菊花采后花部严重劣化，但其机制尚不清楚。为了阐明其机制，对菊花的细胞超微结构、代谢产物、褐变产物和差异表达基因进行了系统研究。在褐变过程中，细胞区室化被严重破坏，绿原酸衍生物和黄酮苷的含量显着下降。首次从过氧化物酶催化绿原酸的模拟褐变反应中纯化鉴定出具有二氢苯并呋喃骨架的褐变产物。此外，通过转录组和qPCR首次鉴定出6个差异表达基因参与氧化酶的调节，其中一个（c76073_g1）通过体外酶活性测定得到验证。该研究阐明了酶促褐变的内在机理，为菊花蒸汽处理加工提供了科学解释，为抗褐变菊花品种的分子育种奠定了基础。