Long Marianne, Millar David J, Kimura Yukiko, Donovan Georgina, Rees Jon, Fraser Paul D, Bramley Peter M, Bolwell G Paul
School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK.
Phytochemistry. 2006 Aug;67(16):1750-7. doi: 10.1016/j.phytochem.2006.02.022. Epub 2006 Apr 17.
Plant secondary metabolism is highly regulated within the major pathways to terpenoids, phenolics and alkaloids. Such regulation can occur at multiple levels from transcription through to the compartmentation of the product. However, the possibility exists for cross-talk between these pathways, the regulation of which is largely unknown at present. Such phenomena are important to understand in the application of plant breeding, where unintended effects of transgenesis or mutation can have an impact on the environment or human health. In an effort to improve dietary antioxidant content of crop plants, the tomato has been a major focus of effort for engineering both lipophilic antioxidants such as carotenoids and hydrophilic antioxidants such as flavonoid glycosides. In this study, a panel of transgenic and mutant tomato lines has been subjected to metabolite profiling in comparison with wild type Ailsa Craig for both carotenoids and phenolics. A range of mutants and transgenic lines were selected showing a range of phenotypes varying from down-regulation through to increased levels of lycopene and beta-carotene. All mutants altered in structural genes for carotenoid biosynthesis showed that perturbations in carotenoid biosynthesis do not generally alter phenolic or flavonoids content significantly even when devoid of carotenoids. Reciprocally, the down-regulation of ferulate 5-hydroxylase had no effect on carotenoid content. In contrast mutants defective in light perception such as the high pigment (hp-1) and LA3771 possess elevated chlorogenic acid and rutin as well as increased carotenoid content. These lines can act as the hosts for further genetic manipulation for increased antioxidant content.
植物次生代谢在萜类、酚类和生物碱的主要生物合成途径中受到高度调控。这种调控可以发生在从转录到产物区室化的多个水平。然而，这些途径之间存在相互作用的可能性，目前对其调控机制知之甚少。在植物育种应用中理解这些现象很重要，因为转基因或突变的意外效应可能会对环境或人类健康产生影响。为了提高作物的膳食抗氧化剂含量，番茄一直是工程化亲脂性抗氧化剂（如类胡萝卜素）和亲水性抗氧化剂（如黄酮糖苷）的主要研究对象。在本研究中，一组转基因和突变番茄品系与野生型艾尔莎·克雷格（Ailsa Craig）进行了类胡萝卜素和酚类物质的代谢物谱分析比较。选择了一系列突变体和转基因品系，它们表现出从下调到番茄红素和β-胡萝卜素水平增加的一系列表型。所有类胡萝卜素生物合成结构基因发生改变的突变体表明，即使缺乏类胡萝卜素，类胡萝卜素生物合成的扰动通常也不会显著改变酚类或黄酮类物质的含量。相反，阿魏酸5-羟化酶的下调对类胡萝卜素含量没有影响。相比之下，光感知缺陷的突变体，如高色素（hp-1）和LA3771，其绿原酸和芦丁含量升高，类胡萝卜素含量也增加。这些品系可作为进一步基因操作以提高抗氧化剂含量研究的宿主。
