Okanin 4′-O-diglucoside from Coreopsis petrophiloides and comments on anthochlors and evolution in Coreopsis

A new chalcone glycoside, okanin 4′-O-diglucoside, is identified from the ray florets of Coreopsis petrophiloides. The known distribution of anthochlors in Coreopsis indicates that two of the most primitive sections produce in their floral parts complex glucosides of butein (and sulfuretin). The more advanced sections synthesize the monoglucosides of okanin (marein), butein (coreospin) and lanceoletin (lanceolin) and their corresponding aurones. The co-occurrence of marein and lanceolin is thus far restricted to members of sect. Coreopsis.     

PHYLOGENETIC IMPLICATIONS OF DIFFERENCES IN NUMBER OF PLASTID PHOSPHOGLUCOSE ISOMERASE ISOZYMES IN NORTH AMERICAN COREOPSIS (ASTERACEAE: HELIANTHEAE: COREOPSIDINAE)

Enzyme electrophoresis was employed to ascertain the number of loci encoding plastid phosphoglucose isomerase (PGI) in species representing all sections of North American Coreopsis. Several species from each of the closely related genera Bidens, Coreocarpus, Cosmos, and Thelesperma were also examined. Species in nine of the 11 sections of North American Coreopsis have two isozymes for plastid PGI, and nearly all species examined in the four other genera also have two (one species has three) isozymes. Since most diploid vascular plants have one plastid PGI isozyme, a gene duplication probably occurred in an ancestor that is common to Coreopsis and the other four genera. That is, two isozymes represent the ancestral number for Coreopsis. The two sections (Electra and Anathysana) apparently lacking the duplication are closely related woody plants restricted largely to Mexico. One gene encoding plastid PGI ostensibly was silenced in a common ancestor of these two sections. This is concordant with other data suggesting a close relationship between the two sections, i.e., they appear to represent a monophyletic group. The electrophoretic data also indicate that 1) the enigmatic monotypic section Silphidium is more closely related to eastern North American sections and not derived from section Electra; and 2) section Anathysana is not ancestral to the three California sections Leptosyne, Pugiopappus, and Tuckermannia; rather, it represents a terminal element closely related to and possibly derived from section Electra.     

A chalcone glycoside from Abies pindrow

The EtOH extract of air-dried stems of Abies pindrow yielded okanin, okanin 4′-O-β-d-glucopyranoside, butein 4′-O-β-d-glucopyranoside, 8,3′4′-trihydroxyflavanone-7-O-β-d-glucopyranoside and a new chalcone glycoside, 2′,3′,4′:3,4-pentahydroxy-chalcone 4′-(l-arabinofuranosyl-α-1→4-d-glucopyranoside-β).     

A cladistic study of North AmericanCoreopsis (Asteraceae: Heliantheae)

A cladistic study of all 44 species of North AmericanCoreopsis was performed using 35 characters. The resulting cladogram indicated that all 11 sections are monophyletic. At the intersectional level, two lineages were revealed, one consisting of six sections occurring almost exclusively in Mexico and California, and another comprising five sections restricted largely to the eastern and southeastern United States. The cladogram is similar to phylogenies produced by less explicit methods but it differs in two major respects: the monotypic sect.Silphidium is placed with other sections from the southeastern United States rather than with Mexican sections, and sect.Anathysana from Mexico is more closely allied with the three California sections than with sect.Electra from Mexico.     

Butein: From ancient traditional remedy to modern nutraceutical

Butein (2′,3,4,4′-tetrahydroxychalcone), a simple chalcone derivative, occurs in many unrelated genera including Butea Dahlia, Coreopsis and Searsia. It is a reputed food additive and a common ingredient of botanicals used in herbal medicine formulations, particularly in Asian countries. Although a simple polyphenol, this molecule exhibits a range of pharmacological properties, most notably acting as a potent protein tyrosine kinase inhibitor and as an antineoplastic agent. Researchers have convincingly demonstrated that butein inhibits the epidermal growth factor receptor in HepG2 cells and the tyrosine-specific protein kinase activities of the epidermal growth factor receptor. In addition, it also exhibits promising anti-inflammatory, antidiabetic, antinephritic, antithrombin, anti-angiogenic and hepatoprotective activities in various animal models. Although this molecule is endowed with an impressive list of biological properties, which have acted as scientific support for its commercialization, there are no review articles that coherently discuss various aspects of this chalcanoid. This review aims to explore the pharmacological relevance of butein, together with its structure–activity relationships and mechanisms of action. In addition, the occurrence, chemical synthesis and biosynthesis of butein are discussed.     

Comparative capitular morphology and anatomy of Coreopsis L. and bidens L. (compositae), including a review of generic boundaries

The capitular and floral morphology and anatomy ofBidens L. andCoreopsis L. were studied. All the North American species ofCoreopsis were studied. Selected species ofBidens from North and South America andCoreopsis from South America were included. The results were compared with previous observations on African species ofBidens (incl.Coreopsis). Emphasis was given to character states of the ray florets, paleae, stylearm apices, outer phyllaries, achenes, and pollen grains. Some of the character states are unique features ofCoreopsis, e.g., globular and elongately conical receptacles, deltoid outer phyllaries, truncate and indistinctly 3–5-dentate, 3–4-lobed ray florets, narrowly spathulate paleae, subulate paleae with linear-filiform upper half, hairy and apically 3-cleft paleae, truncate, convex or shallowly conical stylearm apices with the sweeping hairs limited to the area above the stigmatic surfaces and the orbicular to circular achenes. The cylindric setaceous pappus bristles so commonly encountered inBidens are unknown inCoreopsis. The pappus bristles inCoreopsis are paleaceous but similar, though thicker ones are also found in African species ofBidens (incl.Coreopsis) with winged achenes. Twin-celled hairs (setulae) with differing degrees of wall thickness are found on the achenes ofCoreopsis sect.Pseudoagarista (Mexico and South America),Coreopsis sect.Pugiopappus (California), AfricanBidens with winged achenes (e.g.,B. prestinaria, B. macroptera) and some North AmericanBidens (e.g.,B. aristosa). Similar sclerotic parenchyma make up the achenial wings of species in both genera. These may be interpreted as homologous structures, indicating the underlying similarity of these taxa and their derivation from a common ancestral stock.     

THE FLAVONOIDS OF LASTHENIA (COMPOSITAE)

Lasthenia (Compositae: Helenieae), a western North American-Chilean genus of 16 species, produces 22 flavonoid glycosides. Flavonoids are the chalcones butein and okanin, the aurones maritimetin and sulfuretin, the flavone luteolin, and the flavonols kaempferol, quercetin, and patuletin. The presence or absence of various of these classes of compounds in general follows sectional alignments in the genus, confirms affinities based on morphological and cytological evidence, and suggests relationships of problematical species. Intraspecific variation in flavonoid constituents occurs in several species, and in one taxon intrapopulation variation seems to exist as well. Evolution within Lasthenia has been associated with a loss of the ability to produce or accumulate luteolin, chalcones, and aurones; an increase in diversity of quercetin glycosides; acquisition of the ability to produce patuletin; and an elaboration of glycosylation patterns of patuletin.     

CHLOROPLAST DNA RESTRICTION SITE VARIATION AND THE PHYLOGENY OF COREOPSIS SECTION COREOPSIS (ASTERACEAE)

Restriction site variation in chloroplast DNAs (cpDNAs) of Coreopsis section Coreopsis was employed to assess divergence and phylogenetic relationships among the nine species of the section. A total of fourteen restriction site mutations and one length mutation was detected. Cladistic analysis of the cpDNA data produced a phylogeny that is different in several respects from previous hypotheses. CpDNA mutations divide the section into two groups, with the two perennial species C. auriculata and C. pubescens lacking any derived restriction site changes. The other seven species are united by five synapomorphic restriction site mutations and the one length mutation. These seven species fall into three unresolved clades consisting of 1) the remaining three perennial species, C. grandiflora, C. intermedia, and C. lanceolata; 2) three annual species, C. basalis, C. nuecensoides, and C. nuecensis; and 3) the remaining annual, C. wrightii. The cpDNA data suggest that, although the perennial habit is primitive within the section, the annual species of section Coreopsis have likely not originated from an extant perennial species. The estimated proportion of nucleotide differences per site (given as 100p) for the cpDNAs of species in the section ranges from 0.00 to 0.20, which is comparable to or lower than values reported for other congeneric species. The low level of cpDNA divergence is concordant with other data, including cross compatibility, interfertility and allozymes, in suggesting that species of the section are not highly divergent genetically.     

Flavonoids and phylogenetic reconstruction

Flavonoids have been used successfully for interpreting evolutionary relationships in many groups of angiosperms. These interpretations often have been presented in narrative fashion without specific indications of the kinds of relationships expressed. In this paper a method of phylogeny reconstruction with flavonoid data showing cladistic, patristic, and phenetic relationships is presented. Such a phylogram contains maximal information about flavonoid evolution. As an example, relationships in the North American species ofCoreopsis (Compositae), containing 46 species in 11 sections, are analyzed by this approach. A phylogeny of sections of the genus from previous morphological, chromosomal and hybridization data is compared with that from data on anthochlors (chalcones and aurones). Strong correspondence of these evolutionary interpretations gives support to the hypothesized evolutionary trends within the group.     

PHYLETIC TRENDS IN SECTIONS EUBLEPHARIS AND CALLIOPSIS OF THE GENUS COREOPSIS (COMPOSITAE)

Artificial hybridization, fertility of interspecific and intersectional hybrids, chromosome numbers, and trends in habit and morphology in taxa of sections Eublepharis and Calliopsis of the genus Coreopsis are used to consider the sectional relationships and to derive a presumed phylogeny for the two sections. The two sections are closely related and show a low level of interfertility, but this level is as high as in some interspecific crosses within sections. The sections differ in base chromosome number and achene winging. The problematic C. rosea evidently should remain in section Eublepharis. Both sections probably arose from x = 13 stock resembling C. integrifolia or C. pubescens. Descending aneuploidy was involved in the derivation of section Calliopsis, while chromosome evolution in section Eublepharis has involved polyploidy.     

A new okanin glycoside from the flowers of Coreopsis tinctoria Nutt.

Phytochemical investigation on the water-soluable portions of the EtOH extracts of the flowers of Coreopsis tinctoria Nutt. led to the isolation of six flavonoids, including a new okanin glycoside. The structures of these compounds were identified by spectroscopic analysis, chemical method, and comparison with the literature.     

The phytomelanin layer in traditional members of Bidens and Coreopsis and phylogeny of the Coreopsideae (Compositae)

The phytomelanin layer on the pericarp of cypselae (achenes) of many members of traditional Bidens and Coreopsis, both considered polyphyletic, was studied with the help of scanning electron (SEM) and light (LM) microscopes. It is found to be more prominent in taxa kept within Bidens than in Coreopsis. The black ‘peg‐like’ phytomelanin found in traditional members of Bidens is also found in some members of Coreopsis. Some traditional members of Coreopsis display distinctive pericarp morphology but lack phytomelanin. The pericarp in Bidens is striated, i.e. it is interrupted by longitudinal bands of parenchyma through which the embryo emerges during seed germination. No striation was found in cypselae of traditional Coreopsis. Emergence of the seed in taxa with this type of pericarp morphology is observed to be by rupturing the carpel wall along the sutures. Characteristic morphology of the phytomelanin layer and other cellular secretions on the pericarp in representative species of these genera and segregates as well as the probable adaptive value of this layer and that of the parenchyma is discussed. Coreopsis sect. Tuckermannia (Nutt.) Blake, C. sect. Pugiopappus (A. Gray) Blake, and C. sect. Euleptosyne (A. Gray) Blake, are elevated to the genus Leptosyne DC., while Coreopsis sect. Electra (DC.) Blake is returned to Electra DC. A key to the segregate genera and the remaining sections of Coreopsis as well as new combinations and synonyms are provided.     

COMPARATIVE MORPHOLOGY AND PHYLOGENY OF THE RANALES

Comparative morphological studies of woody Ranales have established the primitive status of the group and hence their key place in angiosperm phylogeny. Significant advances in our knowledge of some ranalian families have been made in recent years. An attempt is made in the present review to bring together a range of morphological data (vegetative and floral anatomy, palynology and embryology) on the Ranales (sensu lato), with particular reference to research work published after the publication of Eames's (1961) book, and to discuss the relationships of the families. Recent ontogenetic studies have shown that the carpel of Drimys is ascidial and not conduplicate as earlier suggested. The inclusion of Degeneria in the Winteraceae is not supported by morphological data. Melville's gonophyll theory has been shown to be inapplicable to the magnoliaceous flower. The pollen of Schisandra is interpreted as derived and specialized rather than primitive as previously supposed. The removal of Schisandra from Magnoliaceae is upheld by morphological evidence. Recent morphological studies do not support a close relationship between Schisandraceae and Illiciaceae suggested by earlier authors. The Canellaceae shows similarities to Winteraceae, Magnoliaceae, Illiciaceae, Eupteleaceae and Myristicaceae. Transitional types of division of pollen mother cells found in Winteraceae, Schisandraceae and Annonaceae and their probable phylogenetic significance have been discussed. The Annonaceae, Winteraceae, Degeneriaceae, Magnoliaceae, Schisandraceae and Cercidiphyllaceae share several embryological features in addition to similarities in floral structure. Ruminate endosperm is regarded either as an archaic feature retained in some taxa or as a later and parallel development in others. Thus its value in assessing relationships seems to be doubtful. Myristicaceae has been shown to be closely related neither to the the Annonaceae nor to the Lauraceae. The suggested relationship of Eupomatiaceae to Annonaceae is not supported by palynology. Floral cortical vascular systems in Magnoliaceae, Annonaceae, Calycanthaceae and Myristicaceae have been compared and it is concluded that they may be vestigial structures. A great deal of similarity has been found between Lauraceae and Calycanthaceae in wood, node, flower structure and embryology. Further floral anatomical evidence has been adduced to support the removal of Scyphostegia from Monimiaceae. The Hernandiaceae show similarities to some members of Monimiaceae while the Gyrocarpaceae resemble the Lauraceae, Gomortegaceae and certain other genera of Monimiaceae. Available evidence from wood and floral anatomy and embryology indicates close relationships among Lauraceae, Monimiaceae and Hernandiaceae. Vegetative and floral anatomical and embryological data seem to indicate a place for the Chloranthaceae in the ranalian complex. Recent anatomical studies in the Nymphaeaceae show that the floral structure is of a primitive type with similarities to the woody Ranales. Available morphological evidence is considered inadequate to express an opinion on the splitting of the family. Ceratophyllaceae is regarded as a highly reduced ranalian family derived most probably from a nymphaeaceous stock. The gynoecium in Berberidaceae is interpreted as monocarpellate. No evidence has been found to support the tricarpellate view. Berberidaceae, Lardizabalaceae and Menispermaceae share several embryological features, while at the same time showing evidence of specialization, each in its own way. Thus they might have arisen from a common stock and early diverged along different lines. The occurrence of several types of embryo sac in Ranunculaceae may well be an indication of specialization, but their probable taxonomic value, if any, is not yet clear. The occurrence of numerous primitive features in Paeonia has been suggested as an argument for its retention in the Ranales. No evidence has been found to preclude the inclusion of Dilleniaceae in the Ranales. On the other hand, as opposed to similarities in wood and pollen characters between Dilleniaceae and Theaceae, floral anatomical and embryological features offer a sharp contrast between the two. The Ranales are believed to be polyphyletic. It has been tentatively suggested that two major phyletic lines may be recognized in each of the woody and herbaceous series: the magnolialian and lauralian lines in the former and the nymphaealian and berberidalian lines in the latter.     

First bacterial chalcone isomerase isolated from Eubacterium ramulus

The human fecal anaerobe Eubacterium ramulus is capable of degrading various flavonoids, including the flavone naringenin. The first step in the proposed degradation pathway is the isomerization of naringenin to the corresponding chalcone. Cell-free extracts of E. ramulus displayed chalcone isomerase activity. The enzyme from E. ramulus was purified to homogeneity. Its apparent molecular mass was estimated to be 136 and 129 kDa according to gel filtration and native polyacrylamide gel electrophoresis, respectively. Chalcone isomerase is composed of one type of subunit of 30 kDa. The purified enzyme catalyzed the isomerization of naringenin chalcone, isoliquiritigenin, and butein, three chalcones that differ in their hydroxylation pattern. N-bromosuccinimide, but also naringenin and phloretin, inhibited the purified enzyme considerably. This is the first report on a bacterial chalcone isomerase. The physiological function of the purified enzyme is unclear, but an involvement in the conversion of the flavanone naringenin to the chalcone is proposed.     

The systematics ofLinum sect.Linopsis (Linaceae)

SectionLinopsis of the genusLinum is the largest and probably the most widespread of the five commonly recognized sections. Using a number of traits, but especially heterostyly, style union, development of false septa in the fruit, pollen morphology, and chromosome number, together with petal pigmentation, number of floral parts, and stigma shape, the section is divided into five subsections:Dichrolinum, with one series;Halolinum with one;Linopsis, with four;Keniense, with one; andRigida, with two. Of these, subsect.Keniense and two series are new, the remaining four subsections and four series are published in a new rank. The inferred relationships of all of the groups and the general distribution of each are discussed. The section ranges from southern Europe and the Mediterranean region to India, eastern and southern Africa and throughout much of North and South America. The primitive species of the section are believed to be in the Mediterranean region.     

Cloning and analysis of two genes for chalcone synthase from Petunia hybrida

Summary With the help of a cDNA probe for a chalcone synthase gene of Petroselinum a cDNA clone for a chalcone synthase gene of Petunia hybrida could be identified. The homologous cDNA allowed the cloning of two genomic EcoRI fragments from Petunia hybrida containing complete chalcone synthase genes. It could be demonstrated that the genes on the two fragments are different and are not allelic but members of a gene family. The two genes are found in a variety of different Petunia lines including in the two conditional mutants affected in chalcone synthase expression in floral buds, White Joy and Red Star. The structure of the two chs genes from Petunia is compared to the chs gene from Antirrhinum majus.Dedicated to Professor Georg Melchers to celebrate his 50-year association with the journal     

Seasonal distribution of the long-nosed bat (Leptonycteris curasoae) in North America: does a generalized migration pattern really exist?

Aim This paper examines the migration of the tropical nectarivorous bat Leptonycteris curasoae considered as a latitudinal migrant that breeds in south-west United States and northern Mexico in spring and migrates southward during fall. We tested the hypothesis that the latitudinal migration occurs only locally given by the local availability of bat resources, leading to migratory movements in zones with seasonal scarcity of resources and to resident bat populations where resources are available throughout the year. Localization We analysed the presence of L. curasoae along its distribution range in North America (between 14°N and 33°N). Study cases were also conducted in three Mexican localities: the Tehuacán Valley (17°48′–18°58′N and 96°48′–97°43′W), Sonoran Desert (28°41′N and 110°15′W), and the coast of Jalisco (19°32′N and 105°07′W). Methods Geographic evidence for latitudinal migration of L. curasoae was analysed using 94-year capture records housed in twenty-two collections of North America. Records were analysed using a Geographical Information System (GIS), in which floral resources and capture records were integrated. Monthly captures in the Tehuacán Valley were conducted during three years and bats abundance and reproductive status were correlated with the phenology of bat resources. Bat captures were also conducted during two consecutive years in an extratropical desert during winter and spring, and during one spring in the coast of Jalisco. Results The latitudinal migration of L. curasoae in North America only occurs at latitudes near 30°N, whereas bats may be residents at latitudes lower than 21°N. Captures were associated always to the availability of floral resources in both geographical and local scales. Main conclusions The existence of resident populations in the tropics with two reproductive events support the hypothesis that migration only occurs in the northern distribution limit of this nectar-feeding bat.     

REPRODUCTIVE BIOLOGY OF APIACEAE. II. CRYPTIC SPECIALIZATION AND FLORAL EVOLUTION IN THASPIUM AND ZIZIA

The classification of specialized floral syndromes has imposed a bias in the interpretation of pollination systems which may be either more generalized, or more specialized, than we have universally acknowledged. An analysis of floral biology in two umbellifer genera, Thaspium and Zizia, was undertaken in order to determine the extent to which cryptic floral or inflorescence variations determine pollination specialization despite a broad visitor spectrum and open reward system. Separate analyses were made of the primary attractants, nectar and pollen, and the secondary attractants, floral color and floral and inflorescence structure in conjunction with analyses of pollinator movements, stigmatic pollen loads and fruit set. All data support the conclusion that cryptic variation in floral and inflorescence characters enhance specialization for pollination by solitary bees or syrphid flies. In addition, evidence is presented for the importance of the oligolectic relationship between taxa of Thaspium and Zizia and the solitary bee, Andrena ziziae. The need for more experimental work both to further define the oligolectic relationship and to understand how floral and inflorescence color and structure affect insect movements is especially revealed by this study. The degree of pollination specialization in Thaspium and Zizia is not uncommon in Apiaceae and has important implications for floral evolution in this family and other plant groups with pollination systems categorized as “promiscuous.”     

Production of yellow colour in flowers: redirection of flavonoid biosynthesis in Petunia

Chalcones are intermediates in the biosynthesis of all flavonoids. In addition, in some species they constitute the major yellow flower pigments. There are two types of chalcones, distinguished by the presence (6′-hydroxychalcones) or absence (6′-deoxychalcones) of a hydroxyl group at the 6′ position of the A-ring. The 6′-deoxychalcones are formed when the enzyme chalcone reductase (CHR) is active in conjunction with chalcone synthase (CHS). In Petunia, only 6′-hydroxychalcones are synthesized, and except in the pollen of some genotypes, they are ephemeral intermediates in flavonoid metabolism. By introducing a CHR cDNA from Medicago sativa under the control of the 35S CaMV promoter into acyanic- or cyanic-flowered lines of Petunia, flower colour was changed from either white to pale yellow or deep purple to pale purple, respectively. Lines were generated that accumulated up to 60% of their petal flavonoids as 6′-deoxychalcones. Several different 6′-deoxychalcones accumulated in the petals of the CHR transgenics. The structures of three of these were determined: one, butein 4-O-glucoside, is a novel plant chalcone. Another chalcone compound was identified in the pollen of the transgenics. The results show that the Petunia chalcone isomerase is unable to use 6′-deoxychalcones as substrates so that 6′-deoxychalcones are stable in Petunia petals, leaves and pollen, but some Petunia flavonoid enzymes can use 6′-deoxychalcones as substrates to modify their structures. The introduction of CHR provides a method to redirect the flavonoid pathway into chalcone production, in order to modify flower colour or to reduce the biosynthesis of other flavonoid types.