Rose Pigments

Biochemical Genetics 17(3-4): 267-296 (Apr 1979)
Distinguishing allozymes and isozymes of phosphoglucoisomerases by electrophoretic comparisons of pollen and somatic tissues
N. F. Weeden, L. D. Gottlieb
Abstract The different electrophoretic patterns of dimeric phosphoglucoisomerases extracted from haploid pollen and diploid somatic tissues of plants may be used to distinguish allozymes and isozymes. The analysis depends on the presence of two alleles at each locus in somatic tissues but only one or the other allele in pollen grains. Consequently, in heterozygotes, heterodimeric allozymes can be identified because they are formed in stems and leaves but not in pollen. The procedure is described in enzymes extracted from the diploid annual plant Clarkia dudleyana, which possesses three gene loci for PGI subunits. Comparison of the electrophoretic patterns of stem and pollen extracts makes it possible in many cases to identify allelic state without breeding tests. The technique also is likely to be useful in the interpretation of zymograms of other multimeric enzymes coded by more than one gene locus.

Bohm: Biosynthesis of Anthocyanins (1999)

Flower Breeding and Genetics: Issues, Challenges and Opportunities for the 21st Century (2007) p. 322
Griesbach; Flavonoid Genetic Engineering (2007)

Park et al: Flavonoid biosynthesis in Rice (2016)
This paper indicates that various substances may be produced by different pathways. I include it here mainly to give further evidence of substrate specificity, i.e., that two enzymes catalyzing the same change may favor different precursors.

Bloom: Pigment evolution in Ruellia (1976)

Anthocyanin Biosynthesis Diagram

Anthocyanins Biblio

Amat et al: Flavonoid colors (2009)

Geissman: Anthocyanins, Chalcones, Aurones and Flavones (1955)

Lawrence: Reactions of anthocyanins & flavones with ammonia & SO2(1929)

Lawrence: Mosaic Dahlia variabilis (1931)

Markham: Investigation of flower color at the cellular level (1998)

Qianqian: Variegation in Paeonia rockii (2017)

Li et al.: Delphinidin in Rubus (2002)

Kim: Pigments of Hibiscus syriacus (1989)

De: Hibiscus syriacus vacuoles (2000)

Werckmeister: Floridorin (1966) delphinidine-3-glucose-rhamnose-p-coumaric-acid

Cohen: Anthocyanin pigments in Glads (1986)

Forkman: Flavonoids as Flower Pigments: The Formation of the Natural Spectrum and its Extension by Genetic Engineering. Plant Breeding 106, 1-26 (1991)

Takanori et al.: Pelargonidin protects Tyrosine (2000)

Harrison & Stickland: Pathways strewn with plant pigments. New Scientist 72(1008): 70-71 (8 July 1976)

Harborne Pigments Biblio

Harborne: Zwitterionic Pigments (1988)

Stintzing et al: A Novel Zwitterionic Anthocyanin From Evergreen Blackberry (Rubus Laciniatus Willd.)

Filhol: On the Chemical Composition of Rosa gallica. The Pharmaceutical Journal and Transactions, 5(4): 185 (Oct 1, 1863)
The author published last year a work relative to the colouring matter of flowers, in which the occurrence of quercitrin was noted.* In again examining the flowers of the red rose, he has ascertained that their astringent property ought to be attributed in great degree to the quercitrin, and that but traces of true tannin can be found. When the petals, coarsely powdered, are exhausted with ether, a yellow tincture is obtained, the flowers retaining their beautiful red colour. The ethereal tincture by evaporation yields a soft greenish-yellow extract. Boiling water dissolves a part of this, forming a yellow solution, whilst a greenish fatty matter is left. This solution gives a deep bottle-green precipitate, with persalts of iron. It is coloured bright yellow by alkalies, and gives with lead salts, lakes of an intense yellow colour; and lastly, when evaporated to dryness, it leaves a dry residue, which assumes a lively yellow tint when moistened with strong hydrochloric acid. Quercitrin may be isolated from the lead precipitate. Rose leaves contain also a large portion of uncrystallizable sugar (20 per cent.), some cyanin, and gallic acid.—Répert, de Pharmacie, May, 1863, and Amer. Journ. Pharmacy.
*Pharm. Journ. second series, vol. iv. p, 133

de Vries: Flavonoids in rose petals (1974)
Quercetin correlated with Cyanidin, Kaempferol with Pelargonidin.

Dubois: Inheritance of color (1980)
Inheritance of colors

de Vries & Dubois: Rose pigments II (1980)
Inheritance of pigments

Chameleon Roses

Arisumi: Rosa Pigments (1963, 1964)
Some of the Floribunda roses and R. chinensis change their flower colour remarkably with the progress of anthesis. "Masquerade" and R. chinensis var. mutabilis are the typical examples. Such colour change was revealed chromatographically to be derived from the formation of the anthocyanins which have the 3-glycosidic configuration such as chrysanthemin and callistephin. These 3-monosides were scarcely detectable in flowers at their early stages of anthesis, but after full bloom a large amount of these pigments became to be recognizable.
[CybeRose note: 'Emmie Gray' and 'Plaisanterie' are other examples.]

Carter: Chameleon China Roses (1940)
Lesmesle belongs to a China type of which there are recorded other varieties whose colour changes were even more startling. Examples of these include Laffay's Courtesan [Belle Courtisane], a pure white changing to fiery red; Prevost's Camellia, pale rose passing to cerise; and Louis Noisette's Bengale à grandes feuilles, whose double blooms opened a delicate rose, changed to carmine, and ended bright purple. A century ago there was a small class — about a dozen — of China roses with spotted, striped and blotched flowers, none of which, so far as I know, exist today, except in one or two rare instances. I certainly do agree that China varieties in general are among the most brilliantly coloured roses in gardens, and that they delight in hot sunny conditions.

CybeRose note 10/22/2021: It occured to me this morning that the ruby border on some mauve roses (e.g., Angel Face, Paradise) suggests that the depth of the lilac coloring is limited by the availability of gallic acid. Otherwise, there would not be enough leucocyanidin to be converted to chrysanthemin and callistephin after the flower opwns.

And some sweet peas:

Gardeners' Chronicle ser. 3. 53: 60 (July 20, 1912)
Dragon Fly, sent by Messrs. ALDERSEY & JONES, is very quaint, for it shows close connection with the ancient Captain Clark and Columbia. The curious purple veins in the standard are a feature, but its chief peculiarity is that the flowers open cream and rapidly change to rosy-purple, finally turning purple and mauve.

'Blue Shift' from Dr. Keith Hammett of New Zealand,"is a Summer flowering sweet pea that has the amazing ability to morph as it ages from pink/mauve to shades of brilliant blues and aquamarines. This is the 'bluest' colour that exists currently in sweet peas."
CybeRose: I take this as evidence that co-pigments [presumably glucosides of kaempferol and quercitin] can have a "chameleon gene" that attaches the glucose molecule to the flavonols as the flower ages.

Blue Roses

Gene-splicing possibillities and efforts

Pushpa Lata: Effects of mutagens on rose pigments. Genética Ibérica 39: 171-186 (1987)
Precursors, kaempferol and quercetin give either yellow or ivory colours to the roses. There is a relationship between the anthocyanins and their precursors in roses (Arisumi, 1963). The kaempferol accompanies pelargonidin and the quercitin is present with cyanidins respectively. It is of interest that myricetin, the precursor of delphinidin was found in the leaves of rose cultivar "Samba" (Arisumi, 1968; Yamaguchi, 1968) and in the flowers of another cultivar "Una Wallace" (Gupta et al., 1957). But delphinidin which is present in most blue flowers of other plants, has not been found in roses.

Roberts & Humphreys: Colour in Roses. The Rose Annual (1980) pp. 133-136
Although the flavonoid pigments of a great many garden varieties of roses have been investigated, it would appear from the literature on this subject that investigations on species roses have been far from exhaustive. It is, therefore, quite possible that new pigments still remain to be discovered. Obviously there is considerable interest in whether or not the flavonoid pigment known as delphinidin, which is able to confer a delphinium blue colour, is present in the genus. It has, in fact, been found by the Japanese biochemist Arisumi in the variety 'Samba' (Kordes 1964) but only in the leaves. Interest has also focused on a pigment called myricetin which is closely similar to quercetin and kaempferol. Myricetin is thought to be a pigment from which delphinidin can be synthesized in the cell. If a species or variety was found with flowers which contained myricetin, it is possible that it could be induced to mutate to a blue flower rose containing delpinindin.

Chemistry of Natural Compounds, Vol. 47, No. 1, 2011 [Russian original No. 1, January-February, 2011]
Anthocyanins from fruit of two species of the genus Rosa
A. R. Novruzov and L. A. Shamsizade
Thus, cyanidin-3-glucoside, cyanidin-3,5-diglucoside, delphinidin-3-glucoside, and delphinidin-3,5-diglucoside were identified for the first time in total anthocyanins from fruit pulp of R. hracziana using chromatography, spectroscopy, total and stepwise hydrolysis, oxidation by H2O2, and comparison with authentic samples. All components with the exception of delphinidin-3,5-diglucoside were found in R. spinosissima anthocyanidins.
    The monoglucosides of cyanidin and delphinidin dominated quantitatively the anthocyanin complex from fruit of both Rosa species.

[CybeRose note: Rosa hracziana Tamamsch. was described by S. G. Tamamshyan in 1949 from the right bank of the River Razdan in Aparan floristic region of Armenia. The species is distinguished by carnose, dark red, stoutish and quite long fruit-stalks.]

Katsumoto, et al.: Engineering the Rose Flavonoid Biosynthetic Pathway Successfully Generated Blue-Hued Flowers Accumulating Delphinidin (2007)
Table 1. Flavonoid composition of commercial bluish rose varieties

Other Blue Flowers (More added 3 May 2020

Pigment + Co-pigment

Pecket: Development of Anthocyanin Pigmentation in Flowers of Lathyrus odoratus. J. Exp. Bot. (1966) 17 (1): 177-184.
ABSTRACT: A quantitative study has been made of developmental changes in the anthocyanins and a flavonol glycoside in the red/blue bicoloured flowers of Lathyrus odoratus L. Anthocyanin formation occurs during the period of most rapid growth of the petals. At maturity about four times as much anthocyanin is present in the standard petal as in the pair of wing petals, which are together comparable in fresh weight to the standard. The pattern of development of flavonol glycoside is quite different; some are formed well before anthocyanin formation occurs and at maturity about six times as much flavonol glycoside is present in the wings as in the standard per unit amount of anthocyanin. Some further evidence is thus provide that the flavonol glycoside may be acting as a co-pigment which modifies the wing petal colour to blue.
INTRODUCTION: IN previous work on flower colour variation in the genus Lathyrus it was found that pigmentation of wild material was always due to anthocyanins of the delphinidin series—delphinidin, petunidin, and malvidin glycosides (Pecket, 1960). No correlation was discovered between flower colour and the presence of particular anthocyanins of the delphinidin series nor with pH. However, a correlation was revealed between blueness of petals and the presence of flavonols (now believed to occur as glycosides). It was suggested that the latter substances acted as co-pigments which modified flower colour towards blue (Pecket, 1960), a view which has been held to account for certain instances of blueness in some other genera since the work of Robinson and Robinson (1931). Evidence supporting this view came from the study of interspecific hybrids in Lathyrus (Pecket and Selim, 1962).

[CybeRose note: The wings have 6 times the co-pigment as the standard, and 1/4th the pigment. That means the co-pigment to pigment ratio in the wings is 24 times that of the standard.]

Harborne: Lathyrus pigments (1960) More pigments, and their rhamnosides.

Osawa: Fuchsia copigmentation (1982)

Xue, Cronk: Molecular basis of Painted Lady sweet pea (2017)

A similar example in roses involving cyanidin and flavonol:

X =
Ballerina   Baby Faurax   Marjorie Fair

Yasuda: Color Expression in Roses (1964-68)
In this paper, the surface structures of petals of the group being velvety dark red were compared morphologically with those of other red group. And the author observed that a certain structural difference between the two groups was a main cause for the different expression of color tone.

Yasuda: Insoluble Anthocyanins (1974-79)
The upper epidermal cells of certain cultivars of black roses, e.g. Charles Mallerin, Josephine Bruce, Bonne Nuit and so on, occasionally hold in the cell vacuoles massive structures colored purple or purplish-red.
     It was observed histochemically that these massive structures showed a color change from either purplish-red or from purple to red with dilute hydrochloric acid and to bluish purple with a weak solution of sodium hydroxide. From these results the massive structure found in the red rose petals can be regarded as the insoluble state of anthocyanin.
     In the surface view of those petals having these massive structures in their upper epidermal cells, the numerous black spots, which are considered to be shadows of epidermal cells, are visible even in petals whose height/width ratio of the upper epidermal cells are within the range of the red petal ones, It can therefore be said that the insoluble state of anthocyanin present in the red rose petals may play an important role in the blackening effect on the petal color.

Yasuda: Studies on "Bluing Effect" in the Petals of Red Rose (1970-85)
Microscopical observations showed that two types of bluing exist in the petals of red rose, the one being due to the presence of bluish spherule in epidermal cells, and the other to the cell sap of bluish tinge. The present paper deals with some cytochemical tests for the bluing of the former type.

Yasuda, Aoyama: Studies on the Development of Black Brown Color in Rose Petals, (1988)
These results offered a new explanation that the black brown of petals such as Black Tea was given by the compound of two colors, one being orange of pelargonidin glycoside and the other being blue of the tannin body causing bluing effects in red petals.

Journal of Genetics, 32: 117-170 (1936)
A Biochemical Survey of Factors for Flower Colour
Rose Scott-Montcrieff

Geschwind on his Erinnerung an Brod: "In not too dry summer and soil the large, densely filled, flat flower is almost purplish-blue or violet-blue, usually with a dark red heart."
CybeRose observation on Baby Faurax: Usually the color is light purple or lilac-pink, rather than this eggplant color which I've only seen in cool, damp weather. Louis XIV also varies considerably. On one occasion, on a cool, damp autumn day, it bore a velvety brown blossom.
CR: Reine des Violettes also seems to be of this group. When its pollen was used on Veilchenblau, the resulting Mme E. Rocque inherited the violet-blue color of its parents.

p. 127. Complex anthocyanins occur more often in nature than might be supposed from the results of isolation and identification. Although some can be obtained in pure and even in crystalline form (monardacin, delphinin, violanin), others are very unstable, dissociating to give the normal glycosides even on drying the petals or on standing for a few days in cold dilute acid. Variation from complex to normal anthocyanin pigmentation during the life of the plant has been noticed by the Robinsons, e.g. the flowers of Hydrangea hortensis contain a complex delphinidin glycoside at first, but this is found to be normal later in the season. Similarly, late grown Hyacinthus "King of the Blues" has not a complex pigment like that of the same variety grown early in heat. The most interesting case recorded is that of the rose "Veilchenblau", which appeared to develop less blue-red flowers in the very dry 1934 season than normally. The bluer petals were separated and found to contain complex as well as normal 3-5-dimonoside, while the redder petals contained less of the complex pigment. It is possible that acylation is an important stage in pigment metabolism.
p. 149. Rosa polyantha: An interesting spray of flowers from a sporting Polyantha Rose ('Paul Krampel') was recently sent by Mr R. E. Cooper of the Royal Botanic Garden, Edinburgh. While the normal flowers were scarlet two distinct mutations had occurred; one to crimson and the other to a dog-rose pink.
    A chemical examination of the pigments involved showed that the normal scarlet flowers were deeply pigmented with pelargonin and some flavone, while in the two sports cyanin took the place of pelargonin, the pale pink flowers having a smaller amount of anthocyanin than either the scarlet or crimson flowers, together with a proportional increase in flavone content. All three types of flowers contained large amounts of tannin.
    The mutation from scarlet to crimson thus involves a change in pigment to a more oxidized anthocyanin with a similar 3-5-dimonosidic residue, while the change from scarlet to pink appears also to involve co-pigmentation and a change in the anthocyanin-flavone balance, and is apparently due to a double mutation.


The section in the green box distinguishes the various anthocyanin pigments. If only the terminal carbon has the -OH, the molecule is pelargonidin. When both of the side carbons have -OH, the molecule is delphinidin. And if the above right molecule has -OCH3 it is peonidin. It appears that a peonidin-based rosacyanin is possible, but probably not in Rosa because, according to reports, the modification occurs after addition of one or two glucose molecules.

Arisumi: Rosa Pigments (1963, 1964)
Another line of approach to the so-called blue roses have been substantiated by "Grey Pearl" which was introduced in 1944. The pigment participated showed complete peculiarities in their chemical behaviours, as they could not been extracted either by the hydrochloric acid or the petroleum ether. Repeated treatments with these solvents could dissolve out the ordinary anthocyanin and carotenoid from the petals of "Grey Pearl", so that the remnant has shown the beautiful bluish tinge. But it was rather lavender and far from the true blueness. From the offsprings of "Grey Pearl" we have reached to "Sterling Silver", which is considered to be the most successful performance of this colour range, but there is no discrimination between the intact petals of "Sterling Silver" and those of "Grey Pearl", from which co-existing anthocyanin and carotenoid were fully removed. Thus we may conclude that the endeavours to produce true blue rose have been directed to eliminate the contaminative pigments from "Grey Pearl", which disturb the effect of the above undefined lavender pigment.

Osawa: Copigmentation of Anthocyanins (1982)
Harborne (1961) attributed the color of blue roses to copigmentation of cyanin with gallotannin or leucocyanidin. K. Toki, N. Saito, M. Yokoi, and Y. Osawa (unpublished results) found that there is no difference in the basic flavonoid pattern between red and blue roses, but the concentration ratio of flavonols to cyanin varies considerably between the two types of roses: it is 30 to 50 in blue roses and only 1 to 3 in red roses. Suspecting copigmentation, they prepared mixed solutions containing 5 x 10-4 M cyanin and varying concentrations of quercitrin, a major flavonol of blue roses.
    In the absorption spectra of the preceding solutions, the authors could not see the 600-nm shoulder, which is characteristic of blue rose spectra. By Sephadex column chromatography, they were able to separate two dull-looking pigments, one reddish-purple and the other bluish-purple (Fig. 12)
    The authors tentatively concluded that the blueness of the Blue Moon roses are due to the dull-purplish pigments together with the flavonol-copigmented cyanin.

[CybeRose note: 'Blue Moon' and 'Mme Violet' are half-siblings, sharing the parent 'Sterling Silver'. Presumably the two "dull-purplish pigments" (above) are the two "rosacyanins" (below), and derived from 'Grey Pearl'.]

Fukui, et al.: Structure of rosacyanin B, a novel pigment from the petals of Rosa hybrida (2002)
Abstract—A novel violet pigment, rosacyanin B, was isolated from the petals of Rosa hybrida cv. ‘M’me Violet’, and its structure was elucidated by spectroscopic methods. rosacyanin B is the first C-4 substituted anthocyanidin isolated from intact plants.

Fukui, et al.: Two novel blue pigments with ellagitannin moiety, rosacyanins A1 and A2, isolated from the petals of Rosa hybrida. Tetrahedron 62(41): 9661-9670 (9 October 2006)
Two novel blue pigments, rosacyanins A1 and A2, were isolated from the petals of Rosa hybrida cv. 'Mme. Violet'. Their structures were elucidated on the basis of high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (HR-FT-ICR-MS), FABMS/MS/MS, 1H, 13C and two-dimensional NMR. The molecular formulas of rosacyanin A1 (1) and A2 (2) are C56H37O31 and C63H41O35, respectively. The structures of rosacyanins A1 and A2 consisted of a common chromophore containing cyanidin with a galloyl group link between positions 4 and 5 of the hydroxyl group of the flavylium nucleus and tellimagrandins (1 or 2). These pigments in which anthocyanidin nuclei linked to ellagitannin through an ether bond are the first compounds isolated from natural sources.

Anderson: Rosacyanins (2008)
The first pyranoanthocyanidin isolated from intact plants, rosacyanin B (35) (Fig. 7.3) was isolated in small amounts from the petals of Rosa hybrida cv. 'M'me Violet' (Fukui et al., 2002). Rosacyanin B is very stable in acidic alcoholic solutions, however, under neutral or weakly acidic aqueous conditions it is precipitated before forming the colorless pseudobase. The structure of this violet pigment, which was revealed mainly by high-resolution fast atom bombardment mass spectrometry (FAB MS) and NMR, contains no sugar units. However, in a recent paper the same group showed that rosacyanin B was connected to tannins in two novel pigments, rosacyanins A1 and A2 (Fukui et al., 2006). These blue pigments had a common chromophore, which contained cyanidin with a galloyl group link between positions 4 and 5 of the hydroxy group of the flavylium nucleus, and tellimagrandin 1 and 2. respectively, at C-3 of the cyanidin nucleus. These are the first known natural pigments in which the flavylium nucleus binds to ellagitannins.

Journal of Food Quality 1-10 (2017)
Profile of the Phenolic Compounds of Rosa rugosa Petals
Andrzej Cendrowski, Iwona Ucibisz, Marta Mitek, Marek Kieliszek, and Joanna Kolniak-Ostek
Rosa rugosa petals are a rich source of phenolic compounds, which determined their antioxidant properties.The aim of this study was to determine the polyphenolic composition of not processed petals of Rosa rugosa collected from the commodity crops and to determine the variability of the contained therein polyphenols between harvesting seasons. Twenty polyphenols were identified by UPLC-ESI-MS. The main fraction of polyphenols was ellagitannins, which are 69 to 74% of the total polyphenols of the petals. In the petals of Rosa rugosa, four anthocyanins have been identified: cyanidin 3,5-di-O-glucoside, peonidin 3-O-sophoroside, peonidin 3,5-di-O-glucoside, and peonidin 3-O-glucoside, of which the predominant peonidin 3,5-di-O-glucoside represented approx. 85% of all the determined anthocyanin compounds. It was found that the petals of Rosa rugosa are a valuable source of bioactive compounds and can be considered as a healthy valuable resource.

CybeRose note: The petals also contain Myricetin 3,5-di-O-glucoside. Myricetin is derived from dihydromyricetin, the precursor to delphinidin.

Nicolas: A Rose Odyssey (1937)
In 1933 I had found a curious sport on 'Margaret McGredy'. The foliage strongly resembled Rugosa but the plant characteristics also leaned toward R. cinnamomea, the wood being almost thornless, as with Cinnamomea. I mentioned this fact to Sam III [McGredy] when I visited him in 1934. Sam could not account for the sport. He had never used species in his breeding. His brother-in-law, Walter I. Johnston, spoke up, 'Your father did much work with species.' We adjourned to the office, where complete hybridizing records from the early days of the firm are kept, one volume for each year, a valuable library. After several hours of research we traced the origin of 'Margaret McGredy' to crosses of Rugosa and Cinnamomea. They were, of course, many generations back. But as these two species are in the blood stream of 'Margaret McGredy' and all modern McGredy roses, the possibility of the sport was explained.

CybeRose note: It may not be a mere coincidence that 'Grey Pearl', the first of the rosacyanin roses, was bred by Sam III from a line derived in part from Rosa rugosa.

Novel compound contained in blue rose (2009) (delphinidin-based rosacyanin)
US 20120011771 A1
Yuko Fukui, Yoshikazu Tanaka
Suntory Holdings Limited
    Since rosacyanins have a cyanidin backbone in a portion of their structure, there the possibility that they are synthesized based on cyanidin, a common precursor with cyanidin or an analog of cyanidin. However, since this remains to be only speculation, what types of substances are actually used as precursors and what types of pathways are used in synthesis have yet to be clearly determined.
    On the other hand, delphinidin is synthesized instead of a portion of the cyanidin in roses in which flavonoid 3 2,5 2-hydroxylase gene is expressed as a result of genetic recombination as previously described. If the aforementioned hypothesis regarding the rosacyanin synthesis pathway, namely that rosacyanin is synthesized by using cyanidin as a precursor, is correct, then rosacyanin would not be synthesized in these genetically modified roses in which cyanidin serving as precursor is essentially absent.
    When the inventors of the present invention conducted an analysis to obtain findings regarding rosacyanin synthesis using the aforementioned genetically modified roses that hardly contain any cyanidin or have a considerably decreased cyanidin content in comparison with a host as described in Patent Document 1 or Patent Document 2, contrary to expectations, a novel compound was found to be present having a chemical structure that clearly differed from that of rosacyanins inherently possessed by roses. Moreover, this novel compound was clearly determined to be uniquely present in roses in which flavonoid 3 2,5 2-hydroxylase gene was expressed by genetic recombination, thereby leading to completion of the present invention.

CybeRose note: I suspect that there is, or could be, a pelargonidin-based rosacyanin in roses. It may have been overlooked because it is not easily distinguished from the cyanidin version. In fact, this may have been seen by Stoddard (1980) in a seedling from Orangeade x Angel Face, that was "soft gray with an orange edging".

CybeRose note 10/22/2021: It occured to me this morning that the ruby border on some mauve roses (e.g., Angel Face, Paradise) suggests that the depth of the lilac coloring is limited by the availability of gallic acid. Otherwise, there would not be enough leucocyanidin to be converted to chrysanthemin or callistephin after the flower opwns.

(Anthocyanic vacuolar inclusions)

Kallam: AVIs (2017)
"... we deduced that AVIs are not bound by a membrane, they are formed when anthocyanins precipitate out of solution in the vacuole, and this is dependent upon pH."

Pourcel: Anthocyanic Vacuolar Inclusions (2010)
Arabidopsis mutants that fail to glycosylate anthocyanidins at the 5-O position (5gt mutant) accumulate AVIs in almost every epidermal cell of the cotyledons, as compared to wild-type seedlings, where only a small fraction of the cells show AVIs.

Plant Biology 6:29 (2006)
New insight into the structures and formation of anthocyanic vacuolar inclusions in flower petals
Huaibi Zhang, Lei Wang, Simon Deroles, Raymond Bennett and Kevin Davies
Although the biosynthetic pathways for anthocyanins and their regulation have been well studied, the mechanism of anthocyanin accumulation in the cell is still poorly understood. Different models have been proposed to explain the transport of anthocyanins from biosynthetic sites to the central vacuole, but cellular and subcellular information is still lacking for reconciliation of different lines of evidence in various anthocyanin sequestration studies. Here, we used light and electron microscopy to investigate the structures and the formation of anthocyanic vacuolar inclusions (AVIs) in lisianthus (Eustoma grandiflorum) petals.
    Results AVIs in the epidermal cells of different regions of the petal were investigated. Three different forms of AVIs were observed: vesicle-like, rod-like and irregular shaped. In all cases, EM examinations showed no membrane encompassing the AVI. Instead, the AVI itself consisted of membranous and thread structures throughout. Light and EM microscopy analyses demonstrated that anthocyanins accumulated as vesicle-like bodies in the cytoplasm, which themselves were contained in prevacuolar compartments (PVCs). The vesicle-like bodies seemed to be transported into the central vacuole through the merging of the PVCs and the central vacuole in the epidermal cells. These anthocyanin-containing vesicle-like bodies were subsequently ruptured to form threads in the vacuole. The ultimate irregular AVIs in the cells possessed a very condensed inner and relatively loose outer structure.
    Conclusion Our results strongly suggest the existence of mass transport for anthocyanins from biosynthetic sites in the cytoplasm to the central vacuole. Anthocyanin-containing PVCs are important intracellular vesicles during the anthocyanin sequestration to the central vacuole and these specific PVCs are likely derived directly from endoplasmic reticulum (ER) in a similar manner to the transport vesicles of vacuolar storage proteins. The membrane-like and thread structures of AVIs point to the involvement of intravacuolar membranes and/or anthocyanin intermolecular association in the central vacuole.

J. Agric. Food Chem. 51: 4990-4994. (2003)
Origin of the Color of Cv. 'Rhapsody in Blue' Rose and Some Other So-called “Blue” Roses.
Gonnet, J-F. 2003.
Flowers of the rose cultivar 'Rhapsody in Blue' display unusual colors, changing as they age, from a vivid red-purple to a lighter and duller purple, which are based on tonalities corresponding to hue angles between 340 and 320° in the CIELAB scale. Unexpectedly, the chemical basis of these colors is among the simplest, featuring cyanin (cyanidin 3,5-di-O-glucoside), the most frequent anthocyanin in flowers, as the sole pigment and quercetin kaempferol glycosides as copigments at a relatively low copigment/pigment ratio (about 3/1), which usually produces magenta or red shades in roses. This color shift to bluer shades is coupled with the progressive accumulation of cyanin into vacuolar anthocyanic inclusions (AVIs), the occurrence of which increases as the petals grow older. In addition to the normal λmax of cyanin at ~545 nm, the transmission spectra of live petals and of epidermal cells exhibit a second λmax in the 620-625 nm range, the relative importance increasing with the presence of AVIs. In petals of fully opened flowers, the only pigmented structures in the vacuoles of epidermal cells are AVIs; their intense and massive absorption in the 520-640 nm area produces a much darker and bluer color than measured for the vacuolar solution present at the very first opening stage. Cyanin is probably "trapped" into AVIs at higher concentrations than would be possible in a vacuolar solution and in quinonoidal form, appearing purple-blue because of additional absorption in the 580-630 nm area. Quite similar pigmentation features were found in very ancient rose cultivars (cv. L’Evêque or Bleu Magenta), also displaying this type of so-called "blue" color.

Phytochemistry. 55(4):327-36 (Oct 2000)
Anthocyanic vacuolar inclusions — their nature and significance in flower colouration.
Markham KR, Gould KS, Winefield CS, Mitchell KA, Bloor SJ, Boase MR.
NZ Institute for Industrial Research and Development
Abstract: The petals of a number of flowers are shown to contain similar intensely coloured intravacuolar bodies referred to herein as anthocyanic vacuolar inclusions (AVIs). The AVIs in a blue-grey carnation and in purple lisianthus have been studied in detail. AVIs occur predominantly in the adaxial epidermal cells and their presence is shown to have a major influence on flower colour by enhancing both intensity and blueness. The latter effect is especially dramatic in the carnation where the normally pink pelargonidin pigments produce a blue-grey colouration. In lisianthus, the presence of large AVIs produces marked colour intensification in the inner zone of the petal by concentrating anthocyanins above levels that would be possible in vacuolar solution. Electron microscopy studies on lisianthus epidermal tissue failed to detect a membrane boundary in AVI bodies. AVIs isolated from lisianthus cells are shown to have a protein matrix. Bound to this matrix are four cyanidin and delphinidin acylated 3,5-diglycosides (three, new to lisianthus), which are relatively minor anthocyanins in whole petal extracts where acylated delphinidin triglycosides predominate. Flavonol glycosides were not bound. A high level of anthocyanin structural specificity in this association is thus implied. The specificity and effectiveness of this anthocyanin "trapping" is confirmed by the presence in the surrounding vacuolar solution of only delphinidin triglycosides, accompanied by the full range of flavonol glycosides. "Trapped" anthocyanins are shown to differ from solution anthocyanins only in that they lack a terminal rhamnose on the 3-linked galactose. The results of this study define for the first time the substantial effect AVIs have on flower colour, and provide insights into their nature and their specificity as vacuolar anthocyanin traps.

Shoji et al: Blue color in tulip (2006)
The entire flower of Tulipa gesneriana cv. Murasakizuisho is purple, except the bottom, which is blue. ... We have established that Fe3+ is essential for blue color development in the tulip.

Wang & Jiji: Resolution of localized small molecule-Aβ interactions by deep-ultraviolet resonance Raman spectroscopy. Biophys Chem. 2011 Oct;158(2-3):96-103.
Fresh, un-oxidized myricetin exhibited excitation and emission fluorescence maxima at 481 and 531 nm, respectively.

Marshall and Collicutt: Breeding For Red Colors in Roses. American Rose Annual, 1983
In our study at Morden, pigment extracts from about 3000 roses were analyzed from 1973 to 1981. These samples were taken from native species, hardy and nonhardy cultivars and a large number of seedlings. Analyses of the results from 45 families of seedlings has given some insight into the color relationships found in roses. Paper chromatography was used to separate pigments. Amounts of pigments after separation were rated in daylight. These ratings were compared to those rated under long wave ultra violet (UV) light where the pink fluorescence of peonin and the yellow fluorescence of pelargonin served to confirm their identification and rating. Light absorption curves for the three pigments from roses and from other sources were developed using a spectrophotometer as a further check.

Werckmeister: Iris colors and pigments. Bull. Amer. Iris Soc. no. 158: 25-33 (1960)
Trivalent aluminum, for example, forms chelates only with organic molecules with three hydroxyl groups of which two must be adjacent to each other. Therefore, of all the known anthocyanidins only delphinidin, petunidin and cyanidin are able to form aluminum chelates.

Plant Pigments, p. 338 (1988), Trevor Walworth Goodwin
Hedin et al. (1983) have observed that cyanidin 3-glucoside is an important factor in the resistance of cotton leaves to the feeding of the tobacco budworm in field experiments. Proanthocyanidins are also present in cotton leaves, but their distribution is not correlated with resistance, as it is with cyanidin 3-glucoside. Laboratory experiments (Table 7.9) confirm the effectiveness of anthocyanins in reducing larval growth in this insect Heliothis viriscens. The mechanism by which anthocyanins exert this effect is not yet clear.
     This discovery does raise the question of whether leaf anthocyanins generally have a protective role against insect feeding. Can some insects perceive the colour of red leaves and avoid feeding, without even tasting them? Further experiments along these lines would be of interest, comparing for example herbivory on ordinary beech leaves with that on copper beech leaves.

Table 7.9 Inhibitory effects of flavonoids on larval growth in the tobacco budworm

Flavonoid ED50
(+)-Catechin 0.052
Proanthocyanidin 0.063
Quercetin 0.042
Quercetin 3-glucoside 0.060
Cyanidin 0.166
Delphinidin 0.138
Cyanidin 3-glucoside 0.070

ED50 = percentage concentration in the diet which reduces larval growth of Heliothis viriscens by 50%.

CybeRose note: This may explain why thrips favor light colored flowers over darker varieties. Mrs. H. K. Woodruff of Cocoa, Florida (Favorite Hybrid Tea Roses in Florida. The American Rose Magazine, May-June 1936) reported that 'Mrs. Charles Bell' is more susceptible to thrips than 'Radiance' and 'Red Radiance'. She also noted that 'Antoine Rivoire' " absolutely disease-proof, as compared to most Florida roses. It seldom 'thrips', which is most unusual in so light a rose."

Nayeshiro, Kyosuke & Hans Eugster, Conrad. (1989). Notiz über Ellagitannine und Flavonol-glycoside aus Rosenblüten. Helvetica Chimica Acta. 72. 985-992.
Note on Ellagitannins and Flavonol Glycosides from Rose Petals [Papa Meilland and Veilchenblau]
Petals from two garden roses proved to be very rich in ellagitannins and flavonol glycosides. Rutin (1), spiraeoside (2), quercitrin (3), isoquercitrin (4), nicotiflorin (5), eugeniin (6), rugosin A (7), rugosin D (10), casuarictin (8), and tellimagrandin I (9) were isolated. Spiraeoside, at physiological pH, exerts a pronounced stabilisation of the anthocyanin colour with enhancement of extinction and bathochromic shift of the absorption maximum in the visible range. The abundance of gallic-acid derivatives 6-10 is in contrast to the apparent inability of rose flowers to produce anthocyanins with a trihydroxylated ring B, a prerequisite in breeding true blue-coloured roses.

Eugster & Märki-Fischer: Carotenoids in Roses (1991)

Eugster & Märki-Fischer: Anthocyanins in Roses (1991)
Pelargonin (62; see Fig. 8) did not appear in roses in color-determining concentrations until 1929. In other garden plants, such as pelargoniums and geraniums, it had been known for years. However, analysis shows that pelargonin is hardly ever formed on its own, but is accompanied in almost all scarlet roses by cyanin (66). 'Gloria Mundi' is one of the very few roses that contains almost pure pelargonin (Fig. 8). Since then, the unexpected appearance of 62 in roses has been traced by many authors (cf. Ref. [62]) to a mutation. Now, however, analyses show that even very old varieties contain significant amounts of 62; examples are R. centfolia muscosa (moss rose, appeared before 1750), 'Königin von Dänemark' (Booth, 1816, alba hybrid?), 'Général Jaqueminot' (Roussel, 1853, hybrid perpetual), 'Crimson Rambler' (Japan, pre 1890, multiflora hybrid), and 'Soleil d'Or'. In contrast to the views of Refs., we also found pelargonin in botanical roses, such as R. pendulina, R. willmottiae, R. rugosa, R. pomifera, and R. gallica versicolor.
....The mysterious 'Crimson Rambler' and 'Königin von Dänemark' also contain unexpectedly high levels of peonin, which throws new light on their unknown pedigrees.

Close-up, papilate surface of 'Ville d'Ettelbruck' rose

Kay, et al. Optical properties of petals (1981)
Petal structure and the distribution of pigments in petals were studied in relation to the functional anatomy of petals and the ways in which petals absorb and reflect light. We examined 201 species from 60 angiosperm families. Anthocyanins, betalains and ultraviolet-absorbing flavonoids were normally confined to the epidermal cells, occurring in solution in the vacuole; carotenoids were found in the epidermis and in smaller quantities in the mesophyll, normally in chromoplasts. In a few species, mainly blue-flowered members of the Boraginaceae and Liliaceae-Scilleae, anthocyanins were confined to the mesophyll.
    Six basic kinds of petal epidermis anatomy were found, sometimes in combination; papillate (112 species) and multiple-papillate (13 species), in which the conical-papillate form of the cells traps incident light and scatters emergent light, with surface striations aiding these functions in many cases; reversed-papillate (4 species), multiple reversed-papillate (29 species), lenticular (32 species) and flat (11 species), all with surface striations in some cases. Light is usually reflected from petals mainly by an aerenchymatous unpigmented reflective mesophyll; in certain species this is replaced by a reflective layer of starch grains in the upper mesophyll.

Nature 435, 757-758 (9 June 2005)
Plant biochemistry: Anthocyanin biosynthesis in roses
Jun Ogata, Yoshiaki Kanno, Yoshio Itoh, Hidehito Tsugawa & Masahiko Suzuki
    Anthocyanin is the principal pigment in flowers, conferring intense red-to-blue cyanic colours on petals and helping to attract pollinators. Its biosynthesis involves glycosylation steps that are important for the stability of the pigment and for its aqueous solubility in vacuoles. Here we describe anthocyanin biosynthesis in roses (Rosa hybrida), which is unlike the pathway used in other flowers in that it relies on a single enzyme to achieve glycosylation at two different positions on the precursor molecule. Phylogenetic analysis also indicates that this previously unknown glucosyltransferase enzyme may be unique to roses, with glycosylation having apparently evolved into a single stabilizing step in other plants.

Figure 1 | A previously undiscovered rose anthocyanidin glucosyltransferase and its phylogeny. a, Comparison of the reaction pathways of anthocyanin glycosylation in the rose and in other plants: the rose glucosyltransferase RhGT1 catalyses two reactions instead of one. 3-GT, glucosyltransferase specific for the hydroxyl group at position 3 on the anthocyanidin molecule.

    Like cyanidin, anthocyanidin 5-O-glucoside is unstable without the additional glycosylation at its 3-OH residue and so does not exist as a stoichiometric intermediate. In the rose pathway, anthocyanidin 3,5-O-diglucoside is therefore the first stable anthocyanin, whereas this is usually anthocyanidin 3-O-glucoside in other plants (Fig. 1a). Anthocyanidin 3,5-O-diglucoside and anthocyanidin 3-O-glucoside are therefore responsible for flower coloration in roses and in other plants, respectively. Although many angiosperms produce anthocyanin derivatives from anthocyanidin 3-O-glucoside as a precursor, this is evolutionarily precluded in roses by their different glycosylation pattern, which may be unique to members of the Rosaceae.

Experientia, 17: 72-73 (1961)
The anthocyanins of roses. Occurrence of peonin.
Harborne, JB and Corner, JJ
Although the garden rose contains a great range of colour varieties, only two anthocyanins have been so far been identified in the petals of cyanic forms. Cyanin (cyanidin 3:5-diglucoside) was isolated from Rosa gallica by WILLSTÄTTER and NOLAN in 19151and a pelargonidin 3:5-dimonoside (presumably the 3:5-diglucoside, pelargonin) was reported in the scarlet polyantha varieties 'Gloria Mundi,' 'Prince of Orange' and 'Paul Crampel' 2,3. The related flavonols, quercetin and kampferol were also known to occur in glycosidic form in rose petals. A third flavonol, myricetin, was recently described as occurring in about 20 Hybrid Tea varieties by SESHADRI et al.4. Since current work in this laboratory has shown that delphinidin and its methylated derivatives occur in association with myricetin in purple or mauve petals of a number of garden flowers5,6, a search for a delphinidin derivative among the anthocyanins of roses was undertaken. In particular, blooms of well established purple and mauve varieties as well as those of the latest and bluest breeding lines were examined.

No delphinidin was found and a re-examination of the rose varieties reported to contain some myricetin4 showed that only kampferol and quercetin were present. In the course of this Survey, however, a third major anthocyanin was discovered in Rosa rugosa and derived varieties, e.g. 'Roseraie de L'Hay'. The pinkish red petals of these plants contain cyanin and the new pigment, which was readily identified as peonin (Tab. I). Since peonin is rare and has only previously been found in quantity in peony blooms7, its presence in pink roses provides a valuable alternative source. Other new sources are the pink flowered garden geranium (Tab. I), a plant already known to contain pelargonin and malvin2, and dark red varieties of Lathyrus odoratus8.

Of the two previously known anthocyanins of roses cyanin is the most widely distributed, being present in all but two of the hundred or so varieties examined. The pelargonidin derivative, whose identity with pelargonin has now been confirmed, occurs in a number of scarlet varieties (e.g. 'Radar' and 'Will Scarlet') besides those already mentioned. Colour in the rose is therefore mainly due to pelargonin, cyanin or peonin or to mixtures of these pigments. Traces of the related 3-glucosides accompany these 3:5-diglucosides in some varieties. Purple or mauve colours are produced by co-pigmentation of cyanin; a fact which has been established by spectral measurements of aqueous acid extracts of the appropriate varieties (Tab. II).

Tab. II Co-pigmentation in mauve roses

Variety Petal
Visual max
in 1% aqu.
HCl (in mµ)
forned on acid
Belle Poitevine red 507 cyanidin
Reine des Violettes violet 509 cyanidin
McGredy 56/944 violet blue 510 cyanidin
McGredy 55/1965 mauve 512 cyanidin
  1. R. Willstätter and T. J. Nolan, Liebigs Ann. 408, 1 (1915).
  2. G. M. Robinson and R. Robinson, Biochem. J. 28, 1712 (1934).
  3. R. Scott-Moncrieff, J. Genet. 32, 117 (1936).
  4. S. R. Gupta, K. S. Pankajamani, and T. R. Seshadri, J. Sci. Ind. Res. B. (India) 16, 154 (1957). [Journal of Scientific & Industrial Research]
  5. J. B. Harborne, Biochem. J. 68, 12 P (1958).
  6. J. B. Harborne, Biochem. J. 74, 262 (1960).
  7. R. Willstätter and T. J. Nolan, Liebigs Ann. 408, 136 (1915).
  8. J. B. Harborne, Nature, Lond. 187, 240 (1960).

S. R. Gupta, K. S. Pankajamani, and T. R. Seshadri, J. Sci. Ind. Res. B. (India) 16, 154 (1957). [Journal of Scientific & Industrial Research]
Petals of the fresh winter flowers were extracted with hot alcohol, hydrolysed with mineral acid, the crude aglycones taken up in ether and analysed by circular paper chromatography using phenol-water (lower layer) as the solvent. Though the anthocyanins present in the red flowers are also extracted by alcohol, after the hydrolysis only the flavonols are taken up by ether and the anthocyanidins are left behind. Among all the varieties examined a maximum of three rings was met with. The innermost ring had Rf 0.33 and indicated the presence of myricetin; the next had Rf 0.57 corresponding to quercetin and the outermost had Rf 0.79 corresponding to kaempferol. No other entities could be detected.

[The following varieties were found to contain at least a trace of myricetin. Only 'Una Wallace' contains myricetin as the major constituent.
Advocate, Betty, Blanche Messing, Charles K. Douglas, Clovelly, Dean Hole, Dorina Neave, Fred J. Harrison, Golden Ophelia, Hadley, Lady Hillingdon, Lucile Barker, Madame Edourd Herriot, Margaret Spaull, McGredy's Sunset, McGredy's Yellow, Mrs. A. R. Waddell, Pharisaer, Sir Henry Segrave, Talisman, Trigo, Una Wallace.]

Wang & Jiji: Resolution of localized small molecule-Aβ interactions by deep-ultraviolet resonance Raman spectroscopy. Biophys Chem. 2011 Oct;158(2-3):96-103.
Fresh, un-oxidized myricetin exhibited excitation and emission fluorescence maxima at 481 and 531 nm, respectively.

J. Japan. Soc. Hort. Sci.) 62(4): 857-866. (1994)
Flower Flavonoid Distribution in Rosa rugosa Thunb. ex Murray and Intcrspccific Rose Hybrids.
Mikanagi et al.
Flower flavonoids of interspecific hybrids between Rosa rugosa Thunb. ex Murray (section Rosa) and Rosa species under sect. Synstytae and sect. Pimpinellifoliae were analyzed to study the mode of flavonoid transmission from parental species to progenies.

  1. The major flavonoids in R. rugosa petals were kaempferol (K) and/or quercetin (Q) 3-sophorosides. These flavonols were present in the petals of all intersectional hybrids with sect. Synstytae and sect. Pimpinellifoliae.
  2. Large amounts of K and Q 3-glucosides were present in the Rosa species under sect. Synstylae as well as in all intersectional hybrids with sect. Rosa.
  3. Unique flavonols, K and Q 4'-glucosides were distributed in the Rosa species under sect. Pimpinellifoliae and were the major flavonols in the intersectional hybrids with sect. Rosa.

The mode of transmission of characteristic flavonoids from parental species to progenies in the three Rosa sections was established by this study. Although the parentage may be unknown, seedlings possessing K and Q 3-sophorosides in their petals can be considered to be hybrids of R. rugosa. Using flavonoid analysis to identify the parentage of R. rugosa hybrids is herein proposed.

Biochemical Systematics and Ecology 23(2): 183-200 (1995)
Flower flavonol and anthocyanin distribution in subgenus Rosa
Mikanagi,Yokoi, Ueda, Saito
Abstract: In a survey of flower flavonoids in 120 taxa from 10 sections of subgenus Rosa, 19 flavonols and six anthocyanins were detected: six kaempferol (K) glycosides; 3-glucoside (in 99% taxa), 3-rutinoside (63%), 3-sophoroside (60%), 3-rhamnoside (70%), 7-glucoside (94%) and 4'-glucoside (4%); and six quercetin (Q) glycosides: 3-glucoside (91%), 3-glucuronide (62%), 3-rutinoside (63%), 3-sophoroside (69%), 7-glucoside (90%) and 4'-glucoside (4%), and seven unidentified flavonols, and two cyanidin glycosides; 3,5-diglucoside (68%) and 3-glucoside (16%) and two peonidin glycosides; 3,5-diglucoside (41%) and 3-glucoside (4%) and two unidentified anthocyanins. From the flavonoid distribution patterns of this analysis, 120 taxa in the subgenus Rosa were divided into three groups as follows.
    The first group was characterized by much containing of K and Q 3-glucosides, and the absence of K and Q 4'-glucosides. Fifty-nine taxa from six sections (Gallicanae 32, Chinenses 14, Synstylae 6, Laevigatae 2, Bracteatae 1 and Banksianae 4) were classified into this group. Small amounts of K and Q 3-sophorosides were found in sections Synstylae, Laevigatae and Bracteatae, but they were sporadically present in sections Gallicanae and Chinenses and were absent in sect. Banksianae. In the second group, 55 taxa from three sections (Caninae 21, Carolinae 7 and Rosa 27) were placed. These plants contained large amounts of K and Q 3-sophorosides and anthocyanins in their petals, but they did not contain 4'-glucosides. The last group contained only one section, Pimpinellifoliae (six taxa). This group was unique in containing a large amount of K and Q 4'-glucosides. Rosa hemisphaerica, however, did not contain any flavonol and anthocyanin except a small amount of K 3-glucoside. By multivariate analyses, three chemotaxonomical groups of subgenus Rosa were confirmed, and interrelationship among these groups was discussed.
Table 2

Biochemical Systematics and Ecology 28: 887-902 (2000)
Anthocyanins in flowers of genus Rosa, sections Cinnamomeae (=Rosa), Chinenses, Gallicanae and some modern garden roses
Mikanagi, Saito, Yokoi, Tatsuzawa
Abstract: Forty-four taxa of three sections (Cinnamomeae (=Rosa) 26, Chinenses 8 and Gallicanae 10) and eight modern garden roses in the genus Rosa were surveyed for their floral anthocyanins. Eleven anthocyanins: 3-glucosides and 3,5-diglucosides of cyanidin (Cy), pelargonidin (Pg) and peonidin (Pn), 3-rutinosides and 3-ρ-coumaroylglucoside-5-glucosides of Cy and Pn, and Cy 3-sophoroside, were isolated from flowers of these taxa and identified by chemical and spectroscopic techniques. Four anthocyanins: Cy 3-rutinoside, Pn 3-rutinoside, Pn 3-ρ-coumaroylglucoside-5-glucoside and Cy 3-sophoroside were found for the first time in Rosa flowers.
     Investigated sections of wild roses showed characteristic distribution of anthocyanins. Cy 3,5-diglucoside was the dominant anthocyanin detected in all three sections, but accumulation of Pn 3,5-diglucoside distinguished sections Cinnamomeae from other sections, and the occurrence of Cy 3-glucoside separates section Chinenses from others.
    Cy 3-sophoroside was detected in large amount in some taxa of section Cinnamomeae: e.g., R. moyesii and its related cultivars, and R. rugosa cv. Salmon Pink. The acylated Cy glycoside was found in all sections and also in some modern garden roses, while the acylated Pn glycoside was detected in the section Cinnamomeae, but not in sections Chinenses and Gallicanae. According to anthocyanin distribution patterns, eight groups were classified chemotaxonomically in genus Rosa.
.....In particular, the blood-red coloured flowers of R. moyesii cv. Geranium contained [cyanidin 3-sophoroside] as 56% of total anthocyanins. This pigment is probably associated with the special colour of that cultivar.
Table 4

Harborne and Wiliams: Anthocyanins and other flavonoids. Nat. Prod. Rep., 2001, 18: 310-333
Rose flowers have been well investigated in the past and glycosidic patterns based on 3-glucoside and 3,5-diglucoside described. However, a recent survey of wild and cultivated roses has uncovered four pigments new to Rosa: cyanidin and peonidin 3-rutinoside, cyanidin 3-sophoroside and peonidin 3-(p-coumarylglucoside)-5-glucoside. The discovery of cyanidin 3-sophoroside is of biosynthetic interest, since the related flavonol 3-sophorosides are dominant copigments in rose petals.

Kamemoto: Purple Anthurium (1996)
Marutani et al. (1987) identified two anthocyanins from both the spathe and spadix of A. amnicola: cyanidin 3-rutinoside and peonidin 3-rutinoside. The former occurred in much larger amounts than the latter. Pelargonidin 3-rutinoside was not detected. Because cyanidin 3-rutinoside (magenta) and peonidin 3-rutinoside (pink) are present in A. amnicola, the lavender to purple color is probably influenced by copigmentation and pH of plant tissues.
[CybeRose note: Mikanagi, et al. (2000) found cyanidin 3-rutinoside and peonidin 3-rutinoside in 'Arthur Hillier' (Rosa macrophylla x R. moyesii).]


Journal of Experimental Botany (25)4: 614-623. (1974)
Factors Determining Petal Colour of Baccara Roses I. The contribution of epidermis and mesophyll
I. Biran, M. Robinson and A. H. Halevy
The partition of light radiated on to the outer epidermis of a Baccara rose petal or on to an intact petal was examined. Most of the red light was either reflected or transmitted whereas other wavelengths and especially the green range were absorbed. When the total amount of light transmitted (epidermis) or reflected (intact petal) increased, a rise in the blue range was recorded and the colour of the petal, determined objectively by CIE or Munsell's method, became more purple.
    Examination of the partition of light in the different layers of the petal revealed that light reflected from the outer epidermis is made up of two parts; one part is reflected directly and the other part is first transmitted through the epidermis, reaches the mesophyll, is reflected from it and is then transmitted through the epidermis. This latter part causes a shift in colour from purple to red.
    Colour differences between different petals on one flower and different parts of the same petal were defined objectively. The change from red to purple colour was connected with vigorous growth of either the petal or epidermal cells, respectively.
    The contribution of the mesophyll in changing the reflectance curve of petals is explained and it is suggested that although the mesophyll is colourless, it contributes to a great extent to the changes occurring in petal colour.

Journal of Experimental Botany 25(4): 624-631. (1974)
Factors Determining Petal Colour of Baccara Roses II. The effect of pigment concentration
I. Biran, M. Robinson and A. H. Halevy
'Blueing' in young and senescing petals was compared in the red rose cv. Baccara. The 'blueing' of senescing flowers is accompanied by a bathochromic shift in the light reflectance curve, a rise in the pH value and a decrease in the malic acid concentration of the petal tissue. These factors indicate that a complex with a co-pigment is produced. Similar changes were not found in the 'blueing' of young flowers, where a decrease was found in pigment concentration per unit weight as well as per unit area of petal. A similar 'blueing' was achieved by diluting a solution of crystalline cyanin. The phenomenon of 'blueing' by dilution is discussed in the light of Bougeur's law.

Journal of Experimental Botany 25(4): 632-637. (1974)
Factors Determining Petal Colour of Baccara Roses III. Effect of the ratio between cyanin and pelargonin
I. Biran, M. Robinson and A. H. Halevy
The changes in colour and in the pigment concentration of the two sides of Baccara rose petals which occur when plants are grown under various temperature regimes, were examined. The inner side of the petal is redder and the predominant pigment is pelargonin whereas the outer petal surface tends to 'blue', and, the predominant pigment on this side is cyanin. The cyanin:pelargonin ratio on the outer side of petals increased three-fold under the influence of low temperatures.
    The outer surface of petals growing for a long period under low temperatures was 'blue' when compared with the red petals which had been subjected to low temperatures for a short period. The cyanin:pelargonin ratio of 'blue' petals was higher than that of red petals. Total pigment content was similar in both types of petal. Flowers grown under high temperatures 'blued' without a concomitant fall in the cyanin:pelargonin ratio.

Chemistry and Biochemistry of Plant Pigments. Edit. T. W. Goodwin (1976)
Chapter 16 — Functions of flavonoids in plants
J. B. Harborne
p 744-5
One example is the garden rose, most varieties of which contain cyanidin and in which mutations to pelargonidin are of rather rare occurrence. The orange-red varieties available today are derived from the dwarf polyantha 'Paul Crampel', which was introduced about 1930. This orange-flowered variety is unusual in that it back-mutates somatically to produce crimson-flowered offshoots, which are pigmented by cyanidin.
    Two wild Antirrhinum species (A. cornutum and A. nuttallianum) have blue delphinidin-containing flowers (Harborne, 1963b), so that there is a reasonable chance that a blue snapdragon will be produced one day.
p 746
Another example is Rosa, in which cyanidin-peonidin mixtures are found almost exclusively in pinker varieties (Rosa rugosa and derived hybrids) whereas crimson and deeper red varieties have only cyanidin. (Harborne, 1961).
p 748
Variations in the amounts of anthocyanin in the petal have profound effects on colour and large discontinuous differences in anthocyanin content have been noted in the flowers of some plant varieties. At one end of the scale, low pigment concentrations give flowers with a faint pinkish blush (e.g. the rose 'Madame Butterfly') and at the other, high concentrations are found in the deep purple-black petals of the tulip 'Queen of the Night' or of the pansy 'Jet Black'.
p 750
Co-pigmentation is also a factor controlling flower colour in the genus Rosa. A blue rose has long been searched for; the rather unsatisfactory mauve and purple varieties (e.g. 'Reine de Violette') so far available contain the cyanidin 3,5-diglucoside of crimson roses co-pigmented with large amounts of gallotannin. The spectral shift in rose is from 507 to 512 nm (Harborne, 1961).
p 753
...protocyanin from the blue cornflower Centaurea cyanus.
Protocyanin, on the other hand, is based on cyanidin 3,5-diglucoside (cyanin) complexed with iron (Bayer et al., 1960; Saito and Hayashi, 1965) and the flavone, apigenin 7-glucuronide-4'-glucoside (Asen and Horowitz, 1974). The crystalline pigment in this case is an iron complex with four molecules of cyanin to three of the flavone (Asen and Jurd, 1967).
p 754
...shifts in flower colour in the rose cultivar 'Better Times' (Asen et al., 1971a) and the garden statice Limonium (Asen et al. 1973) have been attributed to small changes in pH.
p 755
Brown colours formed by magenta cyanidin on a yellow carotenoid background can be seen in the wallflower Cheiranthus cheiri, in Primula polyanthus and in rose varieties, e.g. the coffee-coloured 'Cafe'. Brown colors are not confined to the flower; brown anthers of the flowers of some Solanum plants are coloured by the petunidin glycoside, petanin, on a carotenoid background.
p 756
...the popular rose 'Masquerade' is yellow in bud, orange-yellow when freshly open and deep red before fading. It is clear that yellow carotenoid is produced at an early stage of development, whereas the synthesis of the anthocyanin, cyanin, is delayed until maturity. Significantly, the undersides of red petals have yellow patches, indicating that anthocyanin synthesis is particularly light dependent.
p 761
(3) The common flavonols probably contribute to yellow flower colour when (a) they are methylated or (b) they are present in certain unusual glycosidic forms. Thus a myricetin dimethyl ether (syringetin) contributes yellow colour in the meadow pea Lathyrus pratensis, and isorhamnetin (quercetin 3'-methyl ether) may do the same in the common marigold Calendula officinalis. Quercetin 7- and 4'-glucosides have absorption spectra similar to quercetin itself and may therefore provide some yellow in gorse Ulex europeaus, in Rosa foetida and in other petals in which they occur.
p 766
Many of the plants that show leaf coloration are of considerable ornamental value. The copper beech, a "sport" from the normal green Fagus sylvatica, is pigmented with the 3-galactosides of cyanidin and pelargonidin. Cyanidin glycosides also provide permanent colours in Begonia (B. rex has a deep purple-red leaf), in Coleus (notable for the striking anthocyanin patterning), in Rosa, in Acer and in Rubus.

Journal of Photochemistry and Photobiology A. 136(1-2): 87-91 (31 August 2000)
The photostabilities of naturally occurring 5-hydroxyflavones, flavonols, their glycosides and their aluminium complexes
Gerald J. Smith, Scott J. Thomsen, Kenneth R. Markham, Claude Andary and Dominique Cardon
    In aqueous methanol solution, luteolin and flavonol 3-glycosides exhibited no degradation over periods of up to 15 h of UV irradiation. However, the flavonols studied were all found to degrade and their relative photostabilities correlate with their redox potentials. Quercetin was the least stable. In the presence of aluminium ions, all the flavonoids, including luteolin, were degraded by UV irradiation.
   In contrast to the absorption spectra in dilute solution, the reflectance spectra of both quercetin and luteolin deposited on a cellulosic substrate exhibited strong absorptions beyond 400 nm. On this substrate these flavonoids displayed the characteristic yellow colour associated with flavonoids in some environments. Although the quercetin yellow faded rapidly on exposure to UV radiation, the colour of luteolin darkened. This was due to the formation of a photoproduct absorbing maximally at 450 nm.

Natural Science 14: 143-149 (1899)
Red and Blue Colouring Matters of Flowers
P. Q. Keegan
p. 147. All the genera mentioned are, with the exception of Erythrina, capable of producing a blue or purple flower in some of their specific forms. Fuchsia, Plumbago, Lycium, and Salvia produce one or more pure blue efflorescences; while Pelargonium, Phaseolus, Echinacea, Impatiens, Polygonum, Camellia, Paeonia, and Rosa produce purples more or less deep and frequently approaching deep blue. Of all these, Fuchsia, Plumbago, Pelargonium, Lycium, Polygonum, Camellia, Paeonia, and Rosa contain either an iron-blueing tannin or gallic acid in small quantity, and it is the colouring matter of just these flowers which is most distinctively blued by ammonia vapour or solution. In point of fact, I think it must needs be concluded that in all these instances it is the gallic acid resulting from the oxidation of gallo-tannin or of some nearly allied benzene derivative, which is solely responsible for the blue more or less pure and clear which they so beautifully display. Rosa and Polygonum are exceptional, inasmuch as they are genera which contain a highly phlobaphenic tannin, i.e. a chromogen which on advanced oxidation evolves brown-red or muddy anhydrides more than sufficient to neutralise and overcome any tendency to blue coloration incident to the presence of gallic acid.

Yoon et al.: Chasing the Trails of SNAREs (2011)
Among natural compounds, polyphenols deserve special attention because they are abundant in natural products, have ring structures, and are known to be versatile in protein binding. Some polyphenols in diets can cross the bloodbrain barrier (Ehrnhoeferet al., 2006; Kocisko et al., 2003), suggesting that they can target SNARE proteins in central nervous system once identified as SNARE blockers.

Some Properties of Quercetin