National Institute of Agricultural Sciences, Rural Development Administration, JeonJu 54874, Korea.
Int J Mol Sci. 2020 Feb 4;21(3):1011. doi: 10.3390/ijms21031011.
The onion ( L.) () gene, encoding an enzyme responsible for flavonol biosynthesis in yellow onion, was recently identified and enzymatically characterized. Here, we performed an in vivo feeding assay involving bacterial expression of AcFLS-HRB and observed that it exhibited both flavanone 3-hydroxylase (F3H) and FLS activity. Transgenic tobacco () expressing produced lighter-pink flowers compared to wild-type plants. In transgenic petals, was highly expressed at the mRNA and protein levels, and most AcFLS-HRB protein accumulated in the insoluble microsomal fractions. High-performance liquid chromatography (HPLC) analysis showed that flavonol levels increased but anthocyanin levels decreased in transgenic petals, indicating that is a functional gene in planta. Gene expression analysis showed the reduced transcript levels of general phenylpropanoid biosynthetic genes and flavonoid biosynthetic genes in overexpressed tobacco petals. Additionally, transgenic tobacco plants at the seedling stages showed increased primary root and root hair length and enhanced quercetin signals in roots. Exogenous supplementation with quercetin 3--rutinoside (rutin) led to the same phenotypic changes in root growth, suggesting that rutin is the causal compound that promotes root growth in tobacco. Therefore, augmenting flavonol levels affects both flower color and root growth in tobacco.
洋葱（L.）（）基因，编码在黄洋葱中负责类黄酮生物合成的酶，最近被鉴定并进行了酶学表征。在这里，我们进行了涉及细菌表达 AcFLS-HRB 的体内喂养实验，观察到它表现出类黄酮 3-羟化酶（F3H）和 FLS 活性。表达的转基因烟草（）与野生型植物相比，花朵呈现出更浅的粉红色。在转基因花瓣中，在 mRNA 和蛋白质水平上高度表达，并且大多数 AcFLS-HRB 蛋白积累在不可溶的微粒体部分中。高效液相色谱（HPLC）分析表明，转基因花瓣中的类黄酮水平增加，但花色苷水平降低，表明是在体内具有功能的基因。基因表达分析表明，在过表达烟草花瓣中，一般苯丙烷生物合成基因和类黄酮生物合成基因的转录本水平降低。此外，在幼苗阶段的转基因烟草植物中，主根和根毛长度增加，根中的槲皮素信号增强。外源补充槲皮素 3--芸香糖苷（芦丁）导致根生长的相同表型变化，表明芦丁是促进烟草根生长的因果化合物。因此，增加类黄酮水平会影响烟草的花颜色和根生长。
