Flavonoid Data Research Articles

Systematic aspects of flavonoid biosynthesis and evolution

The use of flavonoids in evaluating contemporary taxonomic systems has relied almost exclusively on the distributional patterns of these compounds among plant groups thought to be “archaic” or “advanced” based on morphological and other non-chemical characters. The many positive correlations between flavonoid distributions and existing taxonomic frameworks have also fostered hypotheses of flavonoid evolution, thereby encouraging their use in plant phylogeny. However, as more surveys have been completed, various inconsistencies have been revealed since compounds thought to be structurally (= biosynthetically) “advanced” have been found in “primitive” or archaic plants. The resulting “devaluation” of the phylogenetic significance of flavonoids above the generic level may be mitigated to some extent by exploiting techniques that draw upon genetics, biosynthetic and statistical methods, as well as a more liberal interpretation of the phylogenetic import of flavonoid distribution in contemporary plants. For example, while individual steps in flavonoid biosynthesis are known to involve one or perhaps two genes per step, recent studies of genetic mutants show that integration of the overall flavonoid biosynthesis in a taxon is often under control by a series of genes, each of which may have qualitative/quantitative effects on several individual steps simultaneously. The production of genetic mutants whose flavonoid complements mimic those of natural taxa suggests the possibility of (1) documenting evolution of infra- and interspecific taxa chemically when morphology lacks discriminatory ability, and (2) shedding light on systematic controversies at higher taxonomic levels (i.e., betalains in the Caryophyllales). The presence of isozymes in the individual enzymatic steps of flavonoid biosynthesis suggests their potential systematic use at the infraspecific level, as has been done with other enzymes (e.g., phosphatases, sulfatases, hydrogenases), or even as high as the subclass level (e.g., dehydroquinate hydrolase). It may even be possible to evaluate the presence of the same flavonoid compound in two species by electrophoretic examination to determine if the enzymes for this final step in its formation are structurally/functionally identical, or only functionally the same (i.e., parallel evolution). Most recently flavonoids have been found in preserved fossil angiosperm leaves, some 22 × 106 K/A years old, so that direct chemotaxonomic comparisons between fossil and extant taxa are now possible and may allow some specific speculation about angiosperm evolution and phytogeography. These new, potentially useful types of data suggest that it is premature to exclude flavonoid data from phylogenetic consideration because of their ubiquity and sometimes contradictory occurrences. Considering the need for more surveys and some consistent form of statistical analysis and quantification of flavonoid distributions (a self-imposed methodological restriction rather than an informational one), overzealous criticism of the use of flavonoid data can be counterproductive, possibly discouraging attempts at creative treatments of flavonoid information beyond certain taxonomic levels.

Flavonoid patterns and systematics in Eleusine

A survey of leaf flavonoids was conducted on Eleusine coracana ssp. coracana and ssp. africana, E. indica, E. multiflora, E. tristachya, E. floccifolia, and E. compressa. Twenty phenolic compounds were detected. Those identified were: orientin, isoorientin, vitexin, isovitexin, saponarin, violanthin, lucenin-1, and tricin. The study revealed a general generic flavonoid pattern except for E. compressa, which occupies an isolated position in Eleusine. Flavonoids of the perennial E. floccifolia and the annuals E. multiflora and E. tristachya are markedly different from those of cultivated E. coracana, suggesting that these species are only distantly related to the crop. The morphologically well defined E. coracana—africana—indica group also forms a unit in respect of flavonoids. Subspecies africana exhibits a higher flavonoid similarity to ssp. coracana (finger millet) than does E. indica. The weedy race of ssp. africana usually combines flavonoids of both the wild and domesticated subspecies. The flavonoid pattern of the dedza race of ssp. africana is identical to that of finger millet, suggesting either a direct origin of the crop from this race, or extensive introgression from the crop into ssp. africana. A lack of qualitative differences in flavonoids between cultivated races of finger millet is indicative of the genetic stability of these compounds. The flavonoid data confirms the domestication of finger millet from ssp. africana.

Flavonoid chemistry, chromosome number and phylogenetic relationships of Helenium chihuahuensis

Five populations of Helenium chihuahuensis were examined for flavonoid content, chromosome number and morphological characteristics. Thirteen flavonoid compounds were detected of which eleven were at least partially identified and were found to be flavones. The chromosome number was determined to be 2 n = 15II . Helenium arizonicum also was found to have a chromosome number of 2 n = 15II . Helenium chihuahuensis, H. arizonicum, H. mexicanum and H. laciniatum were compared by constructing Wagner Networks, both excluding and including flavonoid data, in order to clarify their phylogenetic relationships.

Flavonoid Analysis of Hybridization in Rhododendron Section Pentanthera (Ericaceae)

Flavonoid Analysis of Hybridization in Rhododendron Section Pentanthera (Ericaceae)

Comparison of Numerical Taxonomic Methods Used to Estimate Flavonoid Similarities in the Limnanthaceae

The Limnanthaceae is a small family of North American herbs with uncertain internal relationships. Taxa of the family were compared on the basis of 46 flavonol glycosides occurring in all plant tissues or in petals only. The flavonoid data were analyzed by 3 numerical taxonomic techniques: 1) clustering by the Weighted Pair Group method considering positive and negative matches (Using Simple Matching coefficient) ; 2) clustering by the Weighted Pair Group method considering only positive matches (using Jaccard coefficient) ; 3) Varimax Factor Analysis with rotation. No significantly different results were produced by the two clustering methods. Factor analysis provided a clearer indication of relationships among taxa of the Limnanthaceae than did conventional clustering analysis. Apparently, ordination of taxa in three dimensions is necessary to accurately express relationships between divergent evolutionary lines of the family since much of the expressed variation in flavonoids cannot be accounted for by a one-dimensional clustering technique.

Seed Protein Profiles in the Narrow-Leaved Species of Chenopodium of the Western United States: Taxonomic Value and Comparison with Distribution of Flavonoid Compounds

Water soluble seed proteins from 69 populations representing seven species of Chenopodium were separated electrophoretically. Very little or no intraspecific variation was detected. The use of seed proteins as taxonomic characters was evaluated and compared to data from flavonoid chemistry. Seed proteins are of value in distinguishing C. atrovirens and C. leptophyllum, something which could not be done with flavonoids. Proteins and flavonoid data demonstrated that C. hians and C. leptophyllum are distinct. An analysis of storage proteins failed to differentiate C. desiccatum from C. atrovirens and C. pratericola even though the species are distinct in flavonoids and other characters. Chenopodium atrovirens and C. pratericola produce similar or identical seed proteins, just as they are identical in flavonoids. Seed proteins indicated that plants referable to C. incognitum represent two biological entities, one apparently a minor morphological variant of C. atrovirens and the other conspecific with C. hians. The same interpretation had been given on the basis of flavonoid chemistry. The protein data suggest a close relationship between C. subglabrum on the one hand and C. atrovirens and/or C. desiccatum on the other.

SEED PROTEIN PROFILES IN THE NARROW‐LEAVED SPECIES OF CHENOPODIUM OF THE WESTERN UNITED STATES: TAXONOMIC VALUE AND COMPARISON WITH DISTRIBUTION OF FLAVONOID COMPOUNDS

Water soluble seed proteins from 69 populations representing seven species of Chenopodium were separated electrophoretically. Very little or no intraspecific variation was detected. The use of seed proteins as taxonomic characters was evaluated and compared to data from flavonoid chemistry. Seed proteins are of value in distinguishing C. atrovirens and C. leptophyllum, something which could not be done with flavonoids. Proteins and flavonoid data demonstrated that C. hians and C. leptophyllum are distinct. An analysis of storage proteins failed to differentiate C. desiccatum from C. atrovirens and C. pratericola even though the species are distinct in flavonoids and other characters. Chenopodium atrovirens and C. pratericola produce similar or identical seed proteins, just as they are identical in flavonoids. Seed proteins indicated that plants referable to C. incognitum represent two biological entities, one apparently a minor morphological variant of C. atrovirens and the other conspecific with C. hians. The same interpretation had been given on the basis of flavonoid chemistry. The protein data suggest a close relationship between C. subglabrum on the one hand and C. atrovirens and/or C. desiccatum on the other.

A Systematic Study of the Genus Balduina (Compositae, Heliantheae)

The genusBalduina, endemic to the southeastern United States as interpreted here, includes a complex of three species:B. atropurpurea Harper,B. angustifolia (Pursh) Robinson, andB. uniflora Nutt. The first two species have a chromosome number ofn = 18 andB. uniflora hasn = 36. Hybridization experiments demonstrated strong internal reproductive isolating mechanisms. Flavonoid and sesquiterpene lactone data suggest a possible relationship to the tribe Helenieae.

Flavonoid data and populational observations in support of hybrid status for Populus acuminata

Flavonoid distribution and populational composition at the collection sites of several samples of Populus acuminata strongly suggest that this taxon is an inter-sectional hybrid between P. angustifolia, sect. Tacamahaca and any one of two or three different species of the section Aigeiros, when the entire range is considered. In the vicinity of the type locality, the Aigeiros parent is P. sargentii. Within any population, foliage of trees of P. acuminata is characterized by morphological intermediacy and an essentially additive flavonoid profile, as compared to the two parental taxa present. In habit the trees resemble those of P. sargentii, and habitats at the collection sites were found to be somewhat intermediate. Fifteen flavonoid compounds were consistently present in samples of the putative hybrid. Twelve of these had diagnostic value because they were absent in one of the parental species. One compound, apigenin 7- O- diglucoside , was found only in P. acuminata. In part, our identifications correspond to compounds reported by Crawford in a morphological and chemical study of P. acuminiata.

Internal flavonoid patterns of diploids and tetraploids of two exudate chemotypes of Pityrogramma triangularis (Kaulf.) Maxon

The internal flavonoid patterns of Pityrogramma triangularis fronds were found to distinguish diploids and tetraploids of two exudate chemotypes (the ceroptin and the kaempferol methyl ether types). The flavonoid data suggest that the tetraploid-kaempferol methyl ether chemotype is of alloploid origin involving the two diploid chemotypes because the flavonoid pattern for the former represents a pattern additive of the two diploids, while the tetraploid-ceroptin chemotype may be of autoploid origin, as deduced from the similarity of the diploids and tetraploids.

Thoughts about the taxonomical relationships within the lemnaceae

A survey is given of the taxonomy of the Lemnaceae based on classic morphological characters. This taxonomic system has been compared with the results of phytochemical research, particularly that on flavonoid chemistry by McClure and co-workers; it appears that the classical taxonomical system and the phytochemical data are largely in agreement, except in the case of Wolffia. Subdivisions within the genera based on morphological characters do not coincide with subdivisions based on phytochemical data; in the genus Lemna it appears that flavonoid data, lignin data and morphological data result in three different subdivisions. Therefore, great care is needed for the application of such characters to the taxonomy above the species level. The available cytological data are at present still insufficient to give any indication on systematic relations. It is recommended to direct future research particularly at the flavonoid chemistry and the cytology of the Wolffioideae.

Leaf flavonoids ofGalium sect.Aparinoides (Rubiaceae)

13 taxa belonging to 4 “species groups” ofGalium L. sect.Aparinoides (Jord.)Gren. produce 15 leaf flavonoids: Apigenin-7-diglucoside, Luteolin-7-monoglucoside and 7-diglucoside, Diosmetin, Diosmetin-7-monoglucoside and 7-diglucoside; Kaempferol-3-rutinoside, Kaempferol-3,7-diglucoside, Quercetin, two Quercetin-3-monoglycosides, Rutin, Quercetin-3-rutinoside-7-glucoside, Quercetin-7-glycoside and an unidentified aglycone. TheG. trifidum, G. obtusum andG. palustre groups (with the exception of theG. tinctorium subspecies andG. elongatum) have similar flavone-flavonole patterns, while theG. antarcticum group produces a specific pattern. Leaf flavonoids of theG. trifidum andG. antarcticum group are inhomogenous, becauseG. tinctorium subsp.tinctorium andG. antarcticum lack flavones. For all taxa (with the exception of those of theG. antarcticum group) intraspecific variation is demonstrated, and 4 populations ofG. trifidum subsp.trifidum, G. tinctorium subsp.tinctorium,G. obtusum subsp.obtusum andG. labradoricum even exhibit intrapopulation variation. The implications of flavonoid data on the systematics and the astonishing intrapopulation and intraspecific variation are discussed.

Negatively charged flavones and tricin as chemosystematic markers in the palmae

A survey of 125 species of the Palmae revealed a complex pattern of flavonoids in the leaf. C-Glycosylflavones, leucoanthocyanins and tricin, luteolin and quercetin glycosides were common, being present in 84, 66, 51, 30 and 24% of the species respectively. Apigenin and kaempferol were recorded in only a few species and isorhamnetin only once. Eighteen flavonoids were identified: the 7-glucoside, 7-diglucoside and 7-rutinoside of both luteolin and tricin, tricin 5-glucoside, apigenin 7-rutinoside, quercetin 3-rutinoside-7-galactoside, isorhamnetin 7-rutinoside, orientin, iso-orientin, vitexin, isovitexin and vitexin 7- O-glucoside. Many of the C- and O-flavonoid glycosides were present as the potassium bisulphate salts and negatively charged compounds were detected in 50% of the species. The distribution patterns are correlated with the taxonomy of the family in several ways. Thus, the Phoenicoideae and Caryotoideae have distinctive flavonoid patterns, there is evidence to support the separation of the subfamilies Phytelephantoideae and Nypoideae, and tricin is a useful marker at tribal level. At the generic level, Cocos is clearly separated from Butia, and other Cocoseae and Mascarena and Chamaedorea form well defined groups within the Arecoideae. A numerical analysis of these biochemical data, together with morphological characters, produces a new classification which suggests that the flavonoid data may have more systematic value than is indicated when they are applied to the traditional classification.

Chemosystematics of the Leguminosae. Flavonoid and isoflavonoid patterns in the tribe Genisteae

Leaves of 128 species of 22 genera of the tribe of Genisteae sensu lato were surveyed for flavonoids and isoflavonoids. The isoflavones daidzein, formononetin, genistein and 5- O-methylgenistein were found variously in 73 species; they were detected in all except three of the genera of the Genisteae sensu strictu, but not in five associated genera. Leucoanthocyanidins were only found outside the Genisteae s.l. in Hypocalyptus and Loddigesia. Kaempferol, quercetin, luteolin or C-glycosylflavones based on luteolin or apigenin were noted in the majority of species; the distribution of the first three compounds in the genus Genista (46 species surveyed) largely followed sectional groupings. Luteolin was present in Genista mainly as the 7-glucoside but occurred exceptionally in three species of the section Spartioides as the 5-glucoside, galuteolin, earlier reported in the same family in Galega (Galegeae). The presence of galuteolin and 5-methylgenistein (in 17 spp.) in Genista and of glycoflavones in Cytisus (in 4 of 11 species) were the only clear-cut chemical differences between the morphologically similar genera Cytisus and Genista. The flavonoid data in general support Rothmaler's circumscription of the tribe and discount the more recent classification of Hutchinson.