Molecular phenotyping of lignin-modified tobacco reveals associated changes in cell-wall metabolism, primary metabolism, stress metabolism and photorespiration
Molecular phenotyping of lignin-modified tobacco reveals associated changes in cell-wall metabolism, primary metabolism, stress metabolism and photorespiration
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DOI：
10.1111/j.1365-313x.2007.03233.x
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发表时间：
2007-10-01
期刊：
影响因子：
7.2
通讯作者：
Boerjan, Wout
中科院分区：
文献类型：
--
作者：
Dauwe, Rebecca;Morreel, Kris;Boerjan, Wout
木质素是次生增厚细胞壁的重要组成部分。肉桂酰辅酶a还原酶（CCR）和肉桂醇脱氢酶（CAD）是催化单脂醇生物合成的倒数第二步和最后一步的关键酶。烟草（Nicotiana tabacum）中CCR的下调已被证明会降低木质素含量，而烟草中因CAD而下调的木质素则含有更多的醛类。我们表明，改变烟草中任一或两个基因的表达对转录组和代谢组有深远的影响。基于dna扩增片段长度多态性的转录物分析，结合HPLC和gc - ms的代谢物分析，揭示了单脂醇生物合成中的差异转录物和代谢物，以及单脂醇与其他代谢途径之间的相互作用网络。总的来说，在所有转基因品系中，苯丙素生物合成途径下调，而淀粉动员上调。ccr -下调株系的特征是解毒和碳水化合物代谢水平的变化，而cad -下调株系的分子表型则富集了光和细胞壁相关基因的转录本。此外，转录物和代谢物数据表明，光氧化应激和光呼吸增加，主要发生在ccr下调的品系中。这些对光合装置的预测效应随后被荧光和气体交换测量从生理学上证实。我们的数据提供了植物对改变的单脂醇生物合成反应的分子图。
Lignin is an important component of secondarily thickened cell walls. Cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) are two key enzymes that catalyse the penultimate and last steps in the biosynthesis of the monolignols. Downregulation of CCR in tobacco (Nicotiana tabacum) has been shown to reduce lignin content, whereas lignin in tobacco downregulated for CAD incorporates more aldehydes. We show that altering the expression of either or both genes in tobacco has far-reaching consequences on the transcriptome and metabolome. cDNA-amplified fragment length polymorphism-based transcript profiling, combined with HPLC and GC-MS-based metabolite profiling, revealed differential transcripts and metabolites within monolignol biosynthesis, as well as a substantial network of interactions between monolignol and other metabolic pathways. In general, in all transgenic lines, the phenylpropanoid biosynthetic pathway was downregulated, whereas starch mobilization was upregulated. CCR-downregulated lines were characterized by changes at the level of detoxification and carbohydrate metabolism, whereas the molecular phenotype of CAD-downregulated tobacco was enriched in transcript of light- and cell-wall-related genes. In addition, the transcript and metabolite data suggested photo-oxidative stress and increased photorespiration, mainly in the CCR-downregulated lines. These predicted effects on the photosynthetic apparatus were subsequently confirmed physiologically by fluorescence and gas-exchange measurements. Our data provide a molecular picture of a plant's response to altered monolignol biosynthesis.