Lim Sun-Hyung, Kim Da-Hye, Jung Jae-A, Hyung Nam-In, Youn YeoJin, Lee Jong-Yeol
Division of Horticultural Biotechnology, School of Biotechnology, Hankyong National University, Anseong 17579, Korea.
Research Institute of International Technology and Information, Hankyong National University, Anseong 17579, Korea.
Plants (Basel). 2022 Jun 24;11(13):1681. doi: 10.3390/plants11131681.
Flavonoid biosynthesis requires the activities of several enzymes, which form weakly-bound, ordered protein complexes termed metabolons. To decipher flux regulation in the flavonoid biosynthetic pathway of chrysanthemum ( Ramat), we suppressed the gene-encoding dihydroflavonol 4-reductase (DFR) through RNA interference (RNAi)-mediated post-transcriptional gene silencing under a floral-specific promoter. Transgenic -RNAi chrysanthemum plants were obtained by -mediated transformation. Genomic PCR analysis of -RNAi chrysanthemums propagated by several rounds of stem cuttings verified stable transgene integration into the genome. mRNA levels were reduced by 60-80% in -RNAi lines compared to those in wild-type (WT) plants in ray florets, but not leaves. Additionally, transcript levels of flavonoid biosynthetic genes were highly upregulated in ray florets of -RNAi chrysanthemum relative to those in WT plants, while transcript levels in leaves were similar to WT. Total flavonoid contents were high in ray florets of -RNAi chrysanthemums, but flavonoid contents of leaves were similar to WT, consistent with transcript levels of flavonoid biosynthetic genes. Ray florets of -RNAi chrysanthemums exhibited stronger antioxidant capacity than those of WT plants. We propose that post-transcriptional silencing of in ray florets modifies metabolic flux, resulting in enhanced flavonoid content and antioxidant activity.
类黄酮生物合成需要几种酶的活性，这些酶形成称为代谢体的弱结合、有序蛋白质复合物。为了解析菊花（Ramat）类黄酮生物合成途径中的通量调控，我们通过RNA干扰（RNAi）介导的转录后基因沉默，在花特异性启动子下抑制编码二氢黄酮醇4-还原酶（DFR）的基因。通过介导的转化获得了转基因RNAi菊花植株。对通过几轮茎插繁殖的RNAi菊花进行基因组PCR分析，验证了转基因稳定整合到基因组中。与野生型（WT）植株的舌状花相比，RNAi株系的mRNA水平降低了60-80%，但叶片中没有降低。此外，相对于WT植株，RNAi菊花舌状花中类黄酮生物合成基因的转录水平高度上调，而叶片中的转录水平与WT相似。RNAi菊花舌状花中的总类黄酮含量较高，但叶片中的类黄酮含量与WT相似，这与类黄酮生物合成基因的转录水平一致。RNAi菊花的舌状花比WT植株表现出更强的抗氧化能力。我们认为，舌状花中DFR的转录后沉默改变了代谢通量，导致类黄酮含量和抗氧化活性增强。
