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高等植物中黄酮醇合成酶催化二氢黄酮醇转化生成黄酮醇,是类黄酮代谢途径的关键酶之一。本研究在烟草基因组数据库中搜索获得两个类黄酮合成酶基因,即NtFLS1和NtFLS2,二者表达模式一致,均在叶片中高水平表达。在NtFLS2基因过表达载体的转化株中获得一个共抑制株系KD36,荧光定量PCR分析表明NtFLS1和NtFLS2基因表达水平均被显著抑制,类黄酮途径其它结构基因的表达水平未发生显著变化。KD36株系中二氢槲皮素含量显著上升,是对照的12倍,槲皮素、山奈酚、二氢山奈酚含量未发生显著变化。KD36株系花色更红,花青素含量是对照植株2.4倍。上述研究揭示了烟草黄酮醇合成酶基因的功能,为进一步研究烟草类黄酮代谢提供了一定的理论依据。
Flavonol synthase in higher plants catalyzes the conversion of dihydroflavonols to flavonols, which is one of the key enzymes in the flavonoid metabolism pathway. In this study, two flavonoid synthase genes, NtFLS1 and NtFLS2, were searched in the tobacco genome database. The expression patterns of the two flavonoid synthase genes were consistent and expressed in the leaves at high level. A costimulatory KD36 was obtained from the transformants of NtFLS2 overexpression vector. Fluorescence quantitative PCR analysis showed that NtFLS1 and NtFLS2 gene expression levels were significantly inhibited, and the expression levels of other structural genes in the flavonoid pathway did not change significantly. The content of dihydroquercetin in KD36 strain increased significantly, which was 12 times that of the control, and the content of quercetin, kaempferol and dihydro-kaempferol did not change significantly. KD36 lines were more reddish, anthocyanin content was 2.4 times the control plants. The above study revealed the function of tobacco flavonol synthase gene and provided a theoretical basis for further study of tobacco flavonoid metabolism.