Volatiles affect tea (Camellia sinensis) aroma quality and have roles in tea plant defense against stresses. Some volatiles defend against stresses through their toxicity, which might affect tea safety. Benzyl nitrile is a defense-related toxic volatile compound that accumulates in tea under stresses, but its formation mechanism in tea remains unknown. In this study, l-[2H8]phenylalanine feeding experiments and enzyme reactions showed that benzyl nitrile was generated from l-phenylalanine via phenylacetaldoxime in tea. CsCYP79D73 showed activity for converting l-phenylalanine into phenylacetaldoxime, while CsCYP71AT96s showed activity for converting phenylacetaldoxime into benzyl nitrile. Continuous wounding in the oolong tea process significantly enhanced the CsCYP79D73 expression level and phenylacetaldoxime and benzyl nitrile contents. Benzyl nitrile accumulation under continuous wounding stress was attributed to an increase in jasmonic acid, which activated CsCYP79D73 expression. This represents the first elucidation of the formation mechanism of benzyl nitrile in tea.

中文翻译：

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茶（茶树）中1-苯丙氨酸衍生的苄腈的生化途径及其对采后胁迫的响应

挥发物影响茶（茶树）的香气质量，并在茶树抵御压力中发挥作用。一些挥发物通过其毒性防御压力，这可能会影响茶的安全性。苄腈是一种与防御有关的有毒挥发性化合物，可在压力下积聚在茶中，但其在茶中的形成机理仍然未知。在这项研究中，l- [2H8]苯丙氨酸的进料实验和酶促反应表明，l-苯丙氨酸通过茶中的苯乙醛肟生成了苄腈。CsCYP79D73具有将L-苯丙氨酸转化为苯乙醛肟的活性，而CsCYP71AT96s具有将苯乙醛肟转化为苄腈的活性。乌龙茶加工过程中连续受伤可显着提高CsCYP79D73表达水平以及苯乙醛肟和苄腈含量。连续创伤应力下苄基腈的积累归因于茉莉酸的增加，茉莉酸激活了CsCYP79D73的表达。这代表了首次阐明茶中苄腈的形成机理。