Li Houhua, Flachowsky Henryk, Fischer Thilo C, Hanke Magda-Viola, Forkmann Gert, Treutter Dieter, Schwab Wilfried, Hoffmann Thomas, Szankowski Iris
Institute of Biological Production Systems, Fruit Science Section, Leibniz University of Hannover, Herrenhaeuser Str. 2, 30419 Hannover, Germany.
Planta. 2007 Oct;226(5):1243-54. doi: 10.1007/s00425-007-0573-4. Epub 2007 Jul 6.
Flavonoids are a large family of polyphenolic compounds with manifold functions in plants. Present in a wide range of vegetables and fruits, flavonoids form an integral part of the human diet and confer multiple health benefits. Here, we report on metabolic engineering of the flavonoid biosynthetic pathways in apple (Malus domestica Borkh.) by overexpression of the maize (Zea mays L.) leaf colour (Lc) regulatory gene. The Lc gene was transferred into the M. domestica cultivar Holsteiner Cox via Agrobacterium tumefaciens-mediated transformation which resulted in enhanced anthocyanin accumulation in regenerated shoots. Five independent Lc lines were investigated for integration of Lc into the plant genome by Southern blot and PCR analyses. The Lc-transgenic lines contained one or two Lc gene copies and showed increased mRNA levels for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), flavanone 3 beta-hydroxylase (FHT), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin reductases (LAR), anthocyanidin synthase (ANS) and anthocyanidin reductase (ANR). HPLC-DAD and LC-MS analyses revealed higher levels of the anthocyanin idaein (12-fold), the flavan 3-ol epicatechin (14-fold), and especially the isomeric catechin (41-fold), and some distinct dimeric proanthocyanidins (7 to 134-fold) in leaf tissues of Lc-transgenic lines. The levels of phenylpropanoids and their derivatives were only slightly increased. Thus, Lc overexpression in Malus domestica resulted in enhanced biosynthesis of specific flavonoid classes, which play important roles in both phytopathology and human health.
类黄酮是一大类多酚化合物，在植物中具有多种功能。类黄酮存在于多种蔬菜和水果中，是人类饮食中不可或缺的一部分，并具有多种健康益处。在此，我们报道了通过过量表达玉米（Zea mays L.）叶色（Lc）调控基因对苹果（Malus domestica Borkh.）类黄酮生物合成途径进行代谢工程改造。通过根癌农杆菌介导的转化，将Lc基因导入苹果品种霍尔斯泰纳考克斯（Holsteiner Cox），导致再生芽中花青素积累增加。通过Southern杂交和PCR分析，对5个独立的Lc株系进行了Lc整合到植物基因组中的研究。Lc转基因株系含有1个或2个Lc基因拷贝，并且苯丙氨酸解氨酶（PAL）、查尔酮合酶（CHS）、黄烷酮3β-羟化酶（FHT）、二氢黄酮醇4-还原酶（DFR）、无色花青素还原酶（LAR）、花青素合酶（ANS）和花青素还原酶（ANR）的mRNA水平升高。HPLC-DAD和LC-MS分析显示，Lc转基因株系叶片组织中花青素idaein（12倍）、黄烷-3-醇表儿茶素（14倍），尤其是异构体儿茶素（41倍）以及一些独特的二聚体原花青素（7至134倍）的含量更高。苯丙烷类及其衍生物的含量仅略有增加。因此，在苹果中过量表达Lc导致特定类黄酮的生物合成增强，这些类黄酮在植物病理学和人类健康中都起着重要作用。
