Structures of flavone and flavonol glycosides
SummaryLiterature information on the structures of O-glycosides of flavones and flavonols has been generalized. Using the methods of combinatorial mathematics, the possibility of a great diversity of the structure of the glycosides has been shown without taking into account their acylation, the dimensions of the oxide rings of the sugars, and the nature of the glycosidic bonds.
A Study of Trillium cuneatum and T. luteum
A systematic study was made of two taxa of the genus Trillium subgenus Phyllantherum. }'rorphologi cal, biochemical, ecological, and distributional data were analyzed in order to reevaluate past taxonomic treatments of Trillium cuneatum and T. luteum. Morphological studies revealed the similarities of the two taxa. It was noted that T. cuneatum exhibited great plasticity with respect to morphology, whereas T. luteum shO"tled more homogeneous features. This same relationship was noted with the flavonoids of the two taxa with T. cuneatum showing more variability than T. luteum. The chemistry of the two taxa was unique in that quercetin and kaempferol compounds identified portrayed significant glycoside diversity. A survey of past literature dealing with similar phenolic compounds resulted in an elucidation of the color variation seen ~"i thin allopatric populations of T. cuneatum and led to a belief that T. luteum originally evolved from T. cuneatum as a homozygous recessive form which was favored due to more efficient sexual reproduction accompanying apomictic reproduction. Scanning electron micrographs revealed different types of pollen grains which appeared to have taxonomic significance. The abaxial surfaces of the bracts apparently iii were identical. Photom:icrographs were useful also in revealing spiders as possible pollinating agents within the genus. Predator--prey relationships and cryp tic coloring are discussed as possible factors affecting reproductive success of the plants. iv Recent taxonomic treatments were reviewed and possible taxonomic considerations were considered. Based on the results of this study and past work of other botanis ts, it was concluded that the two taxa should be recognized as distinct spocies in keeping with traditional tre a t~ents. It is believed that the two taxi represent a good case of directional selection resulting in divergent evolution . Whether this divergence will result in more speci Rtion in the future or whether the two taxa l.~ill merge into a single unit via introgressive hybridization, is a stimulating academic consideration.
FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM. I. SPECIES SPECIFIC PIGMENTATION PATTERNS
A B S T R A C T Previous work on cotton flower pigments is outlined. The major flavonoids are glycosides of gossypetin, quercetin, and kampferol. Twelve flavonol glycosides have been tentatively isolated and identified, while a number of minor components remain unidentified. The gossypetin glycosides are gossypin, gossypitrin and a C7-linked glycoside of unknown sugar residue. The quercetin glycosides include isoquercitrin, rutin, a third C3-linked glycoside with unknown sugar residue, quercimeritrin and a second C7-linked glycoside with sugar residue unknown. The kampferol glycosides include trifolin, kampferol rutinoside and 2 other C3-linked glycosides with unknown sugar residues. The major anthocyanin throughout the genus is cyanidin. Mutants which affect visible flower color were studied in 3 species (G. arboreum, G. hirsutum, and G. barbadense). The majority of these mutants act to decrease or prevent the synthesis of gossypetin glycosides. The only exceptions to this are the mutants at the Ya locus in G. arboreum, which affect all of the C7linked glycosides in one case, and in the other reduce over-all flavonol production. In all instances, the species could be positively identified by the residual array of pigments not affected by the mutant alleles concerned; i.e., visual similarity of phenotypes did not obscure the basic pattern of pigmentation characteristic of the different species. WITHIN any one species, striking differences in flower pigment constitution are often attributable to the effects of genetically simple mutants. It is quite likely that the same or similar mutants could occur in parallel in several species. Therefore, in comparing species which have flowers of different colors, the possible effects of superficial mutational differences have to be compensated for, if a valid taxonomic comparison is to be made. On the other hand, those components of a pigment array that can be shown to be independent of simple mutational differences can be used with confidence in interspecific comparisons. The purpose of this paper is to compare pigment components of mutant phenotypes to those of the usual pigment phenotype to determine if the mutants alter the flavonoid nmakeup to such a degree that the species under consideration can no longer be distinguished by its array of petal flavonoids. The Gossypium species which carry