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The Identification and Inheritance of the Yellow Flower Pigments in Desmodium Sandwhicense E. Mey.
|Title:||The Identification and Inheritance of the Yellow Flower Pigments in Desmodium Sandwhicense E. Mey.|
|Authors:||Walker, Phyllis Ann|
|Abstract:||The purpose of this thesis was to study the chemistry and genetics of flower pigments in D. sandwicense E. Mey. Eleven parental lines, exhibiting flower color variation from near-white to light and dark purple, were selected for this study. Crosses were attempted among the lines, using white-flowered plants as the female parents. Due to difficulties encountered in the crossing, attributable to technique and/or environmental conditions, and/or inherent in the species, no true crosses were obtained. Consequently, the inheritance studies proposed were abandoned.|
Pigment identification using paper chromatography involved two steps: 1) analysis of the aglycones present and 2) analysis of the glycosides present. Aglycone extracts were obtained using hydrolysis of the petal tissue, and glycosides were obtained by extraction with methanol or methanol-HCl. BAW was the primary solvent system used; other systems were HAc-HCl, 1%HCl, 15%HAc, 60%HAc, 60%IP, (IPnisopropyl alcohol), Forestal, and TAW. The components of these solvent systems are readily available in the literature. Identifications were based upon Rf-values for the various solvent systems and upon color reactions in visible and ultraviolet light, both with and without ammonia vapor.
Sufficient quantities of concentrated extract were difficult to obtain, thereby hindering conclusive identification of the compounds present. It was indicated that the phenolic composition of the petals was much more complex than previously reported. An earlier study demonstrated the presence of an anthocyanidin, malvidin, as well as glucose, and a single anthocyanin, malvidin 3, 5-diglucoside. In addition, the presence of eight yellow pigments and three colorless compounds, which fluoresced in ultraviolet light, was demonstrated (42, 44).
In the present study, a considerably larger number of components than the above was indicated. Tentative identification of the aglycones and glycosides is presented below.
Aglycones: malvidin, kaempferol, quercetin, ferulic acid, ellagic acid. Less conclusive evidence suggested: gossypetin, mimuletin, patuletin, isorhamnatin, p-coumaric acid, sinapic acid. Glycosides: malvidin 3, 5-diglugoside. At least two glycosides of flavones and/or flavonols; one may have been kaempferol 3-glucoside.
Interrelationships among the pigments in the production of phenotypic color variation in the species may be summarized as follows:
Delphinidin*: blue, mauve
Malvidin (methylation): reddening
Malvidin 3, 5-diglucoside (3,5-diglycosylation): intensifying
* Malvidin is a methylated derivative of delphinidin.
Possible scylation*: dulling
Co-pigmentation, due to presence of flavones.
Background effects, due to:
1) Presence of flavones, flavonols: cream or yellow background, if these pigments are present in high concentrations; etc.;
2) Chalcones, aurones(?): orange or yellow background; and/or
3) Carotenoids(?): background effect of plastid-borne pigments
Flavonols and flavones: give “body” to white petals; may contribute to whiteness
Chalcones and aurones (?): orange- or yellowing
Carotenoids (?) + anthocyanins: result in purple or magenta colors
pH effects (?), due to:
1) Low pH: reddening; or
2) High pH: blueing; colorless pseudo-base.
The interaction of these effects results in very complicated interrelationships in the production of phenotypic flower color in D. sandwicense. The conclusive identification of all pigments and phenolic compounds present, and the determination of their distribution and concentration among color classes, would have to precede elucidation of the above interactions.
* The possibility of acylation was suggested by the tentative identification of cinnamic acids.
|Appears in Collections:||
M.S. - Agronomy and Soil Science|
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