Flower Pigmentation

We are now familiar with the carotenoids and the flavan derivatives and they represent the most important flower pigments. Carotenoids are responsible for yellow to red colors and flavan derivatives for whitish, yellow, red, and blue colors. Anthocyanins are the red and blue flavan pigments. 

The realization of a particular flower coloration is determined by a number of factors, the most important of which are considered below. 

This completes our discussion of the phenols, the second largest group of secondary plant substances after the terpenoids. Listing the biosynthetic pathways in order of increasing importance for higher plants, phenols are formed by the acetate-mevalonate pathway, the acetate-malo-nate pathway, and, particularly, the shikimic acid pathway (Fig. 112). The cinnamic acids occupy a central position in phenol metabolism, participating as they do in the biosynthesis of all other important phenols. 

In the discussion of translation, the amino acids were taken for granted. In this chapter we must discuss several aspects of their biosynthesis. Their name is derived from the fact that in all frequently occurring amino acids an amino group is found in the a-position to a carboxyl group. We shall concern ourselves first with the origin of this reduced N and then see how it is transferred to the C skeleton, i.e. how the amino acids are formed. 

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Blumen blatt, n. petal. erde, /, garden mold, gelb, n. any yellow flower pigment. kohl, m. cauhflower, seite, /. (Leather) hair side, staub, m. pollen. tee, m. imperial tea. topf, m. flower pot. 

TLC and HPLC have been applied for the separation of the flower pigments of some Delphinium species. Anthocyanins were extracted with 70 per cent aqueous ACN containing... 

K. Honda, K. Tsutsui and K. Hosokawa, Analysis of the flower pigments of some Delphinium species and their interspecific hybrids produced via ovule culture. Sci. Hort. 82 (1999) 125-134. 

The functions of phenylpropanoid derivatives are as diverse as their structural variations. Phenylpropanoids serve as phytoalexins, UV protectants, insect repellents, flower pigments, and signal molecules for plant-microbe interactions. They also function as polymeric constituents of support and surface structures such as lignins and suberins [1]. Therefore, biosynthesis of phenylpropanoids has received much interest in relation to these functions. In addition, the biosynthesis of these compounds has been intensively studied because they are often chiral, and naturally occurring samples of these compounds are usually optically active. Elucidation of these enantioselective mechanisms may contribute to the development of novel biomimetic systems for enantioselective organic synthesis. 

Martin, C. et al.. Molecular analysis of instability in flower pigmentation of Antirrhinum majus, following isolation of the pallida locus by transposon tagging. EMBO J., 4, 1625, 1985. 

Elomaa, P. et al., Agrobacterium-mtdidXtd transfer of antisense chalcone synthase cDNA to Gerbera hybrida inhibits flower pigmentation. Biotechnology, 11, 508, 1993. 

Eorkmann, G., Elavonoids as flower pigments the formation of the natural spectrum and its extension by genetic engineering, Plant Breeding, 106, 1, 1991. 

Nakayama, M. et al.. Identification of cyanidin 3-0-(3",6"-beta-dimalonyl-beta-glucopyranoside) as a flower pigment of chrysanthemum Dendranthema grandiflorum), Biosci. Biotechnol. Biochem., 61, 1607, 1997. 

Norbaek, R. et al.. Flower pigment composition of Crocus species and cultivars used for a chemotaxonomic investigation, Biochem. Syst. Ecol, 30, 763, 2002. 

Similarly, Karrer and oo-workers discovered that the carotenoid flower pigment trollixanthin (XV),103 as veil aa the related substances anthoroxsnthin, M, i4 violaxanthin, 1 and epoxylutein, 10-(1 all contain epoxide units. The. subject of naturally-occurring carotenoid epoxides ha been reviewed recently.1. 8 8 and attention called to the possible need for revision in certain of the structural assignments made by Karrer and hie associates.885... 

Jorgensen, E.C. and Geissman, T.A. 1955. The chemistry of flower pigmentation in Antirrhinum majus color genotypes. 111. Relative anthocyanin and aurone concentrations. Biochem. Biophys. 55 389-402. 

Ellestad GA. 2006. Structure and chiroptical properties of supramolecular flower pigments. Chirality 18 134-144. 

Weiss D. 2000. Regulation of flower pigmentation and growth Multiple signaling pathways control anthocyanin synthesis in expanding petals. Physiol Plant 110 152-157. 

Pyrylium ions are six-membered heterocycles in which a positively charged sp2-hybridized oxygen replaces the nitrogen in pyridine. The pyrylium ring appears in many naturally occurring flower pigments. 

DE VETTEN, N, QUATTROCCfflO, F MOL, J., KOES, R., The anil locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals, Genes Dev., 1997,11, 1422-1434. 

So far we have started the chain with acetate, but many other starter units are used, Some important groups of compounds use shikimic acid metabolites such as cinnamic acid (Chapter 50) as starter units. They include the widespread plant flavones and the anthocyanidin flower pigments. 

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