| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5515664 | Plant Physiology and Biochemistry | 2016 | 9 Pages |
â¢Silencing of two DFR genes of flavonoid biosynthetic pathway can change the flower color in tobacco.â¢Silencing of DFR genes has affected in the genes expression of the flavonoid biosynthetic pathway in flower.â¢The level of small RNA production in DFR RNAi tobacco is consistent with the color change in flower and seed.
To examine flux regulation in the flavonoid pathway of tobacco flowers, we suppressed two genes for dihydroflavonol 4-reductase (NtDFR 1 and 2) by RNA interference (Ri)-mediated post transcriptional gene silencing in pink-flowered tobacco. Two phenotypes were observed, pale pink (DFR-Ri_PP)- and white (DFR-Ri_W)-flowered lines. The relative mRNA levels of NtDFR genes in DFR-Ri_PP and DFR-Ri_W lines were reduced by 79%-95% relative to non-transformed (NT) plants. DFR-Ri_W lines had five-fold higher levels of small interference RNAs compared to DFR-Ri_PP lines. Expression of eight structural genes in the flavonoid pathway was significantly increased in DFR-Ri_W lines but not in DFR-Ri_PP lines based on quantitative RT-PCR. Anthocyanin contents correlated with flower color, with a reduction of 72%-97% in DFR-Ri_PP and DFR-Ri_W lines. Decreases in anthocyanin in flower were proportional with reductions of proanthocyanidin content in seeds. Two pale pink lines, DFR-Ri_PP 17 and 20, with anthocyanin decreases and the lowest level of DFR gene silencing, had higher (dihydro) flavonol production than a white flowered line, DFR-Ri_W 67. This finding suggests that suppression of DFR can increase the total levels of flavonoids due to (dihydro) flavonol biosynthesis. Our observations that higher suppression of DFR had a greater influence on the expression of flavonoid biosynthetic genes demonstrates the key role of DFR in the pathway and allows selection among DFR-Ri lines for plants with specific gene expression profiles to fine-tune flux through the pathway.
