Tikunov Yury M, Verstappen Francel W A, Hall Robert D
Center for BioSystems Genomics, Wageningen, The Netherlands.
Methods Mol Biol. 2007;358:39-53. doi: 10.1007/978-1-59745-244-1_3.
Plants are a fabulously rich source of naturally volatile metabolites, which are derived from a range of contrasting biochemical pathways (e.g., mono-, di-, and sesquiterpenoids, benzoates, alcohols, esters). Such volatiles may immediately be released from the plant or they may be stored, e.g., in glycosylated form for release later "on demand." Certain roles for these molecules have already been determined in that they can function as attractants (e.g., to pollinators, seed dispersers, and others) or as protectants (repellants, pathogen inhibitors, and so on). The flavor and fragrance of plant materials to humans and other animals are also, to a great extent, determined by natural volatiles. Other more sophisticated roles have also been elucidated where plant volatiles have been shown to be involved either as signal molecules to attract the predators of damaging herbivorous insects or potentially even as signal molecules warning other plants of imminent danger. As such, detailed knowledge of these components can be valuable in relation to breeding crop varieties for enhanced product quality or for achieving improved resistance to pathogens and insects. Furthermore, knowledge of the metabolites can result in a corresponding knowledge of the genes responsible for their synthesis and this can lead to dedicated strategies for their in vitro production through, e.g., reverse genetics in heterologous microbial expression systems in fermentors for the production of high-value fine chemicals. Various analytical techniques based on gas chromatography-mass spectrometry have been devised for the analysis of this complex group of metabolites. Two of these key methods are detailed in this chapter.
植物是天然挥发性代谢物极其丰富的来源，这些代谢物源自一系列截然不同的生化途径（例如，单萜类、倍半萜类、二萜类、苯甲酸酯类、醇类、酯类）。此类挥发物可能会立即从植物中释放出来，或者它们可能会被储存起来，例如以糖基化形式储存，以便日后“按需”释放。这些分子的某些作用已经确定，它们可以作为引诱剂（例如，吸引传粉者、种子传播者等）或作为保护剂（驱避剂、病原体抑制剂等）发挥作用。植物材料对人类和其他动物的风味和香气在很大程度上也由天然挥发物决定。其他更复杂的作用也已得到阐明，植物挥发物已被证明要么作为信号分子吸引有害食草昆虫的捕食者，要么甚至可能作为信号分子警告其他植物即将来临的危险。因此，详细了解这些成分对于培育提高产品质量或增强对病原体和昆虫抗性的作物品种可能很有价值。此外，对代谢物的了解可以相应地了解负责其合成的基因，这可以导致通过例如在发酵罐中的异源微生物表达系统中的反向遗传学来制定专门的体外生产策略，以生产高价值的精细化学品。已经设计了各种基于气相色谱 - 质谱联用的分析技术来分析这一复杂的代谢物组。本章详细介绍了其中两种关键方法。
