pelargonidin and aromadedrin

Vitis vinifera has been thought to be unable to produce pelargonidin-type anthocyanins because its dihydroflavonol 4-reductase (DFR) does not efficiently reduce dihydrokaempferol. However, in this study, pelargonidin 3- O-glucoside was detected in the skins of V. vinifera 'Pinot Noir', 'Cabernet Sauvignon', and 'Yan73', as well as in the flesh of 'Yan73' by HPLC-ESI-MS/MS. Additionally, pelargonidin 3- O-(6-acetyl)-glucoside was detected in 'Yan73' skin and flesh for the first time. To further confirm the presence of pelargonidin-type anthocyanins in these grape cultivars, their DFRs were cloned, expressed in Escherichia coli, and purified. An enzyme-activity analysis revealed that V. vinifera DFR can reduce dihydrokaempferol to produce leucopelargonidin, although it prefers dihydroquercetin and dihydromyricetin as substrates. Thus, the existence of a pelargonidin-based anthocyanin-biosynthetic pathway was confirmed in V. vinifera via mass-spectrometric and enzymatic methods and redirected anthocyanin biosynthesis in V. vinifera L. cultivars.

Topics: Alcohol Oxidoreductases; Anthocyanins; Biocatalysis; Chromatography, High Pressure Liquid; Citrus sinensis; Flavonoids; Oxidation-Reduction; Plant Proteins; Tandem Mass Spectrometry; Vitis

Anthocyanins are polyphenolic pigments which provide pink to blue colours in fruits and flowers. There is an increasing demand for anthocyanins, as food colorants and as health-promoting substances. Plant production of anthocyanins is often seasonal and cannot always meet demand due to low productivity and the complexity of the plant extracts. Therefore, a system of on-demand supply is useful. While a number of other (simpler) plant polyphenols have been successfully produced in the yeast Saccharomyces cerevisiae, production of anthocyanins has not yet been reported.. The results reported in this study demonstrate the proof-of-concept that S. cerevisiae is capable of de novo production of the anthocyanin pelargonidin 3-O-glucoside. Furthermore, while current conversion efficiencies are low, a number of clear bottlenecks have already been identified which, when overcome, have huge potential to enhance anthocyanin production efficiency. These results bode very well for the development of fermentation-based production systems for specific and individual anthocyanin molecules. Such systems have both great scientific value for identifying and characterising anthocyanin decorating enzymes as well as significant commercial potential for the production of, on-demand, pure bioactive compounds to be used in the food, health and even pharma industries.

Topics: Anthocyanins; Arabidopsis; Batch Cell Culture Techniques; Biological Products; Biosynthetic Pathways; Culture Media; Fermentation; Flavanones; Flavonoids; Glucose; Kaempferols; Metabolic Engineering; Phenylpropionates; Plant Proteins; Proof of Concept Study; Saccharomyces cerevisiae

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.

Topics: Alcohol Oxidoreductases; Anthocyanins; Cytochrome P-450 Enzyme System; Flavonoids; Flowers; Mixed Function Oxygenases; Mutation; Nicotiana; Oxidoreductases; Petunia; Plant Proteins; Plants, Genetically Modified