Orange- to red-colored flowers are difficult to produce by conventional breeding techniques in some floricultural plants. This is due to the deficiency in the formation of pelargonidin, which confers orange to red colors, in their flowers. Previous researchers have reported that brick-red colored flowers can be produced by introducing a foreign dihydroflavonol 4-reductase (DFR) with different substrate specificity in Petunia hybrida, which does not accumulate pelargonidin pigments naturally. However, because these experiments used dihydrokaempferol (DHK)-accumulated mutants as transformation hosts, this strategy cannot be applied directly to other floricultural plants. Thus in this study, we attempted to produce red-flowered plants by suppressing two endogenous genes and expressing one foreign gene using tobacco as a model plant. We used a chimeric RNAi construct for suppression of two genes (flavonol synthase [FLS] and flavonoid 3'-hydroxylase [F3'H]) and expression of the gerbera DFR gene in order to accumulate pelargonidin pigments in tobacco flowers. We successfully produced red-flowered tobacco plants containing high amounts of additional pelargonidin as confirmed by HPLC analysis. The flavonol content was reduced in the transgenic plants as expected, although complete inhibition was not achieved. Expression analysis also showed that reduction of the two-targeted genes and expression of the foreign gene occurred simultaneously. These results demonstrate that flower color modification can be achieved by multiple gene regulation without use of mutants if the vector constructs are designed resourcefully.

中文翻译：

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通过多种类黄酮生物合成基因的基因工程生产红花植物。


在一些花卉植物中，通过常规育种技术很难产生橙色至红色的花朵。这是由于天竺葵素的形成不足，天竺葵素赋予其花朵橙色到红色的颜色。此前研究人员报道，通过在矮牵牛中引入一种具有不同底物特异性的外源二氢黄酮醇4-还原酶（DFR），可以产生砖红色的花朵，而矮牵牛不会自然积累天竺葵素色素。然而，由于这些实验使用二氢山奈酚（DHK）积累的突变体作为转化宿主，该策略不能直接应用于其他花卉植物。因此，在这项研究中，我们尝试使用烟草作为模型植物，通过抑制两个内源基因并表达一个外源基因来生产红花植物。我们使用嵌合 RNAi 构建体来抑制两个基因（黄酮醇合酶 [FLS] 和类黄酮 3'-羟化酶 [F3'H]）和非洲菊 DFR 基因的表达，以便在烟草花中积累天竺葵素色素。 HPLC 分析证实，我们成功生产出含有大量额外天竺葵素的红花烟草植物。正如预期的那样，转基因植物中的黄酮醇含量降低了，尽管没有实现完全抑制。表达分析还表明，两个靶基因的减少和外源基因的表达同时发生。这些结果表明，如果载体构建体设计巧妙，可以通过多基因调控来实现花色修饰，而无需使用突变体。