Structure and Molecular Stacking of Anthocyanins ‐ Flower Color Variation
TL;DR: In this paper, the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking.
Abstract: In 1913 Willstatter made the striking observation that the same pigment can give rise to different colors. Thus, the same pigment, cyanin, is found in the blue cornflower and in the red rose. Willstatter attributed the variety of flower colors to different pH values in solution. Indeed, anthocyanin changes its color with pH; it appears red in acidic, violet in neutral, and blue in basic aqueous solution. Willstatter's pH-theory for explaining flower color variation is still to be found in major text books of organic chemistry. Very recently, however, reinvestigation has disclosed that the color variation and stabilization of anthocyanins in aqueous solution could have other causes, namely self-association, copigmentation and intramolecular sandwich-type stacking. The stacking would be mainly brought about by intermolecular or intramolecular hydrophobic interaction between aromatic nuclei such as anthocyanidins, flavones and aromatic acids. In addition, hydrogen bonds and charge transfer interactions may also be involved. The most interesting molecular complexes of anthocyanins are the metalloanthocyanins such as commelinin and protocyanin (blue cornflower pigment). These seemingly pure blue complexes each consist of six anthocyanin and six flavone molecules and two metal ions; their molecular weight is nearly 10000. A structure is proposed for commelinin.
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TL;DR: Current knowledge regarding the reaction mechanisms involved in some of these processes and the structures of the resulting products is reviewed, and their effects on organoleptic and nutritional quality are also discussed.
657 citations
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...Color intensification resulting from interactions of anthocyanins with other compounds (ie, copigmentation) is well documented (56, 57)....
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TL;DR: This work down-regulated the endogenous dihydroflavonol 4-reductase (DFR) gene and overexpressed the Irisxhollandica DFR gene in addition to the viola F3'5'H gene in a rose cultivar, resulting in the accumulation of a high percentage of delphinidin and a novel bluish flower color.
Abstract: Flower color is mainly determined by anthocyanins. Rosa hybrida lacks violet to blue flower varieties due to the absence of delphinidin-based anthocyanins, usually the major constituents of violet and blue flowers, because roses do not possess flavonoid 3',5'-hydoxylase (F3'5'H), a key enzyme for delphinidin biosynthesis. Other factors such as the presence of co-pigments and the vacuolar pH also affect flower color. We analyzed the flavonoid composition of hundreds of rose cultivars and measured the pH of their petal juice in order to select hosts of genetic transformation that would be suitable for the exclusive accumulation of delphinidin and the resulting color change toward blue. Expression of the viola F3'5'H gene in some of the selected cultivars resulted in the accumulation of a high percentage of delphinidin (up to 95%) and a novel bluish flower color. For more exclusive and dominant accumulation of delphinidin irrespective of the hosts, we down-regulated the endogenous dihydroflavonol 4-reductase (DFR) gene and overexpressed the Irisxhollandica DFR gene in addition to the viola F3'5'H gene in a rose cultivar. The resultant roses exclusively accumulated delphinidin in the petals, and the flowers had blue hues not achieved by hybridization breeding. Moreover, the ability for exclusive accumulation of delphinidin was inherited by the next generations.
408 citations
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...…color depending on the pH of the vacuole in which anthocyanins localize; their color is bluer in weakly acidic or neutral pH, and redder in acidic pH. Co-pigments, usually flavones and flavonols, cause a bathochromic shift of anthocyanins when they stack with anthocyanins (Goto and Kondo 1991)....
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01 Jan 2000
TL;DR: The UBIC gene opens a new biosynthetic pathway in plants and regulates tropane alkaloid metabolism in plants an plant cell cultures K.M. Davies and R.J. Verpoorte.
Abstract: Details of Contributors. Preface. 1. Plant secondary metabolism R. Verpoorte. 2. General strategies R. Verpoorte, et al. 3. Agrobacterium, a natural metabolic engineer of plants P.J.J. Hooykaas. 4. Particle gun methodology as a tool in metabolic engineering M.J. Leech, et al. 5. Modulation of plant function and plant pathogens by antibody expression R. Fischer, et al. 6. Transcriptional regulators to modify secondary metabolism J. Memelink, et al. 7. Plant colour and fragrance K.M. Davies. 8. Metabolic engineering of condensed tannins and other phenolic pathways in forage and fodder crops M.P. Robbins, P. Morris. 9. Metabolic engineering of crops with the tryptophan decarboxylase of Catharanthus roseus V. De Luca. 10. Metabolic engineering of enzymes diverting amino acids into secondary metabolism J. Berlin, L. Fecker. 11. Modification of plant secondary metabolism by genetic engineering R. Hain, B. Grimmig. 12. Expression of the bacterial UBIC gene opens a new biosynthetic pathway in plants L. Heide. 13. Regulation of tropane alkaloid metabolism in plants an plant cell cultures K.M. Oksman-Caldentey, R. Arroo.
278 citations
TL;DR: The anthocyanin pigments consist of two or three chemical units: an aglycon base or flavylium ring (anthocyanidin), sugars, and possibly acylating groups.
Abstract: Anthocyanins belong to a large group of secondary plant metabolites collectively known as flavonoids, a subclass of the polyphenol family. They are a group of very efficient bioactive compounds that are widely distributed in plant food. Anthocyanins occur in all plant tissues, including leaves, stems, roots, flowers, and fruits. Research on phenolic compounds through the last century, from the chemical, biochemical, and biological points of view, has focused mainly on the anthocyanins. Anthocyanins have structures consisting of two aromatic rings linked by three carbons in an oxygenated heterocycle (i.e., a chromane ring bearing a second aromatic ring in position 2). The basic chromophore of anthocyanins is the 7-hydroxyflavilyum ion. Anthocyanin pigments consist of two or three chemical units: an aglycon base or flavylium ring (anthocyanidin), sugars, and possibly acylating groups. Only six of the different anthocyanidins found in nature occur frequently and are of dietary importance: cyanidin, delphinid...
201 citations
TL;DR: A classification of models based on their complexity is proposed, defined as whether and how they model the mechanisms of chromatic adaptation and receptor opponency, the nonlinear association between the stimulus and its perception, and whether or not models have been fitted to experimental data.
Abstract: The recognition that animals sense the world in a different way than we do has unlocked important lines of research in ecology and evolutionary biology. In practice, the subjective study of natural stimuli has been permitted by perceptual spaces, which are graphical models of how stimuli are perceived by a given animal. Because colour vision is arguably the best-known sensory modality in most animals, a diversity of colour spaces are now available to visual ecologists, ranging from generalist and basic models allowing rough but robust predictions on colour perception, to species-specific, more complex models giving accurate but context-dependent predictions. Selecting among these models is most often influenced by historical contingencies that have associated models to specific questions and organisms; however, these associations are not always optimal. The aim of this review is to provide visual ecologists with a critical perspective on how models of colour space are built, how well they perform and where their main limitations are with regard to their most frequent uses in ecology and evolutionary biology. We propose a classification of models based on their complexity, defined as whether and how they model the mechanisms of chromatic adaptation and receptor opponency, the nonlinear association between the stimulus and its perception, and whether or not models have been fitted to experimental data. Then, we review the effect of modelling these mechanisms on predictions of colour detection and discrimination, colour conspicuousness, colour diversity and diversification, and for comparing the perception of colour traits between distinct perceivers. While a few rules emerge (e.g. opponent log-linear models should be preferred when analysing very distinct colours), in general model parameters still have poorly known effects. Colour spaces have nonetheless permitted significant advances in ecology and evolutionary biology, and more progress is expected if ecologists compare results between models and perform behavioural experiments more routinely. Such an approach would further contribute to a better understanding of colour vision and its links to the behavioural ecology of animals. While visual ecology is essentially a transfer of knowledge from visual sciences to evolutionary ecology, we hope that the discipline will benefit both fields more evenly in the future.
137 citations
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...When gradual and continuous changes in the producing mechanisms correlate linearly with spectral changes, the spectral space can be very useful (e.g. pH-determined variation from red to blue in flowers; Goto & Kondo, 1991)....
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References
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TL;DR: Theorie zur Erklarung der Blutenfarbenvariation is immer noch in wichtigen Lehrbuchern der Organischen Chemie zu finden.
Abstract: 1914 machte Willstatter die uberraschende Beobachtung, das ein Pigment verschiedene Farben hervorbringen kann. So findet sich in der blauen Kornblume und in der roten Rose das gleiche Pigment: Cyanin. Die Vielfalt an Blutenfarben fuhrte Willstatter auf unterschiedliche pH-Werte in Losung zuruck. Anthocyan andert in der Tat die Farbe mit dem pH-Wert: Es erscheint rot in saurer, violett in neutraler und blau in alkalischer wasriger Losung. Willstatters pH-Wert-Theorie zur Erklarung der Blutenfarbenvariation ist immer noch in wichtigen Lehrbuchern der Organischen Chemie zu finden. Vor kurzem jedoch zeigten erneute Untersuchungen, das die Farbvariation und die Stabilisierung von Anthocyanen in wasriger Losung andere Ursachen haben konnten, namlich Selbstassoziation, Copigmentierung und intermolekulare sandwichartige Stapelung. Die Stapelung kame hauptsachlich durch intermolekulare oder intramolekulare hydrophobe Wechselwirkungen zwischen aromatischen Ringen etwa von Anthocyanidinen, Flavonen und aromatischen Sauren zustande. Zusatzlich konnten Wasserstoffbrucken und Charge-Transfer-Wechselwirkungen eine Rolle spielen. Die interessantesten Molekulkomplexe von Anthocyanen sind Metalloanthocyane wie Commelinin und Protocyanin (Pigment der blauen Kornblume). Diese rein blau erscheinenden Komplexe bestehen aus jeweils sechs Anthocyan- und sechs Flavonmolekulen sowie zwei Metall-Ionen. Ihr Molekulargewicht betragt beinahe 10000. Ein annahernder Strukturvorschlag liegt fur Commelinin vor.
41 citations