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PubMed2004

The structure of colleters in several species of Simira (Rubiaceae).

BACKGROUND AND AIMS: Colleters are secretory structures consisting of a parenchymatic middle axis surrounded by a layer of palisade-like epidermal cells. Colleters occur in a large number of rubiaceous species. Their function is to protect the developing shoot apex. They are also taxonomically useful in the Rubiaceae. This study characterized the structure of the colleters of Simira glaziovii, S. pikia and S. rubra and the biochemistry of secretions in S. glaziovii. METHODS: Stipules of the shoot apices of the three species studied were collected at Barragem de Saracuruna, in Rio de Janeiro state, Brazil. The samples were fixed according to the usual methods for light and electron microscopy. Secretion stipules of S. glaziovii were washed with 0.1 m Tris-HCl plus 0.1 %Triton X-100 to extract proteins and carbohydrates. KEY RESULTS: Colleters in these species are located at the base of the stipule. Each species shows a different pattern of distribution. They form as emergentia from the stipules. Simira glaziovii was different from the other two species because it exhibited vascular traces. The epidermal cells of colleters have dense cytoplasm, nuclei, small vacuoles, endoplasmic reticulum, Golgi apparatus, mitochondria and extraplasmic spaces if they are secretory. The outer cell wall of the mature colleters differs from the outer cell wall of stipule cells and immature colleters. Both carbohydrates and proteins were found in secretions from the stipules of S. glaziovii. CONCLUSIONS: Few ultrastructural differences were noted among the three species. These secretory structures not only protect the shoot apex, but also have taxonomic importance below the genus level.

Epithelial Cells↗
PubMed2004

Between-year changes in functional gender expression of Palicourea padifolia (Rubiaceae), a distylous, hummingbird-pollinated shrub.

BACKGROUND AND AIMS: Because distylous species have two hermaphroditic style-length floral morphs, they face two sex allocation problems: the equilibrium morph ratio and the optimal allocation to pollen and seed production in each floral morph. Gender specialization is expected among distylous species when floral morphs differ in reproductive output. However, spatio-temporal variability in female reproductive output between morphs needs to be investigated to fully understand patterns of sexual expression and gender specialization in distylous plants. Between-year variation in flower and fruit production of hummingbird-pollinated Palicourea padifolia (Rubiaceae) was examined, focusing on functional gender expression of long- and short-styled morphs and comparing their reproductive performance in five consecutive years (1998-2002). METHODS: Between-year variation in inflorescence, floral bud and fruit production was monitored and quantified. These traits were then used as parameters to determine functional gender differences between floral morphs through time. KEY RESULTS: Inflorescence production varied among years but no significant differences were found between floral morphs. Long-styled plants initiated more floral buds per inflorescence every year than short-styled plants, suggesting higher allocation to pollinator attraction and, potentially, an increase in male fitness through pollen donation. Although fruit production was similar between morphs, their functional gender shifted across years. CONCLUSIONS: The gender expression inconsistency across years is surprising because a number of floral characters and attributes that contribute to differently attracting and rewarding effective pollinators in P. padifolia suggest gender specialization. The evidence that morphs of distylous species might specialize in functional gender mostly comes from differences among populations in seed production and non-equilibrium morph ratios based on 1-year field population surveys. The results suggest that more sampling through time is needed to detect gender specialization among distylous species with a perennial habit.

Flowers↗
PubMed2002

Phylogeny of Gaertnera Lam. (Rubiaceae) based on multiple DNA markers: evidence of a rapid radiation in a widespread, morphologically diverse genus.

Phylogenetic relationships among 28 of the 68 species of the paleotropical genus Gaertnera (Rubiaceae) and two related genera were inferred from nucleotide sequence variation in four nuclear DNA (nDNA) markers: the internal transcribed spacers of nuclear rDNA (ITS), the large and small copies of phosphoenolpyruvate carboxylase (PepC-large and PepC-small), and triose phosphate isomerase (Tpi). Phylogenetic analysis of the combined nDNA dataset suggested that Gaertnera is monophyletic, but genetic variation among species was insufficient to reconstruct well-supported relationships within the genus. This was counter to expectations based on the very distinct morphologies and widespread distribution of the genus (West Africa to Sulawesi). Molecular clock analyses suggested variable dates of origin for Gaertnera depending upon the calibration method used. The most plausible calibration implies that Gaertnera migrated to Africa during the early Tertiary, possibly via a boreotropical land bridge and suggests that Gaertnera started to radiate 5.21 +/- 0.14 million years ago. This implies that range expansion in the group has occurred via a number of long-distance dispersal events rather than vicariance. The molecular clock estimate in turn estimated an unusually rapid lineage diversification rate within the radiation of 0.717-0.832 species/million years, comparable to those estimated for radiations on oceanic islands. Although low interspecific competition levels may have contributed to the diversification of Gaertnera on Mauritius, the mechanisms driving the rapid radiation of the group in other parts of its range remain elusive.

Base Sequence↗
PubMed2006

Flower morphology, nectar features, and hummingbird visitation to Palicourea crocea (Rubiaceae) in the Upper Paraná River floodplain, Brazil.

We investigated flower morphology, nectar features, and hummingbird visitation to Palicourea crocea (Rubiaceae), a common ornithophilous shrub found in the riparian forest understory in the Upper Paraná River floodplain, Brazil. Flowers are distylous and the style-stamen dimorphism is accompanied by other intermorph dimorphisms in corolla length, anther length, and stigma lobe length and form. We did not observe strict reciprocity in the positioning of stigma and anthers between floral morphs. Flowering occurred during the rainy season, October to December. Nectar standing crop per flower was relatively constant throughout the day, which apparently resulted in hummingbirds visiting the plant throughout the day. Energetic content of the nectar in each flower (66.5 J) and that required daily by hummingbird visitors (up to 30 kJ) would oblige visits to hundreds of flowers each day, and thus movements between plants that should result in pollen flow. Three hummingbird species visited the flowers: the Gilded Sapphire (Hylocharis chrysura), the Black-throated Mango (Anthracothorax nigricollis), and the Glittering-bellied Emerald (Chlorostilbon aureoventris). The frequency of hummingbird visitation, nectar features, and the scarcity of other hummingbird-visited flowers in the study area, indicate that P. crocea is an important nectar resource for short-billed hummingbirds in the study site.

Animals↗
PubMed2002

"Devil's gardens" in the Ecuadorian Amazon--association of the allelopathic tree Duroia hirsuta (Rubiaceae) and its "gentle" ants.

The relationship between the myrmecophytic tree Duroia hirsuta (Rubiaceae) and its associated, minute, non-aggressive Myrmelachista sp. (Formicinae) ants is poorly investigated, even though the small understory tree is surrounded by a conspicuos zone almost devoid of vegetation. As to the cause of these barely vegetated "Devil's Gardens", two alternative interpretations exist in the literature: the pruning activity of ants and allelopathy. We investigated the mutualistic Duroia-Myrmelachista system in the Ecuadorian Amazon, focusing on the phenomenon of the areas of reduced vegetation, as well as on the natural history of the associated ants. We conducted planting experiments and behavioral studies, including coccoids, the third partner in this mutualism. Because the well-studied Triplaris americana (Polygonaceae) possesses analogous vegetation free surroundings created by the assiduous mechanical pruning of its mutualistic ant partner (Pseudomyrmex sp.), parallel comparative investigations of this ant-plant association were conducted. The two systems are not equivalent; it was demonstrated that the remarkably inactive Myrmelachista ants are not responsible for the bare areas around Duroia plants. Instead, we regard allelopathy as the causative agent for the clear zones.

Animals↗
PubMed2005

Growth inhibition of foodborne and nosocomial pathogens by aqueous fraction of bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae).

The crude methanol extract of Bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae) showed a good and broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacteria. The activity was increased on fractionation (hexane, dichloromethane and water), particularly in the aqueous fraction which was more active than the methanol extract and streptomycin (no activity was shown against tested moulds). Both the hexane and dichloromethane fractions were inactive. The objective of this experiment was to investigate the antibacterial activity of hexane, dichloromethane, and aqueous fractions of Argostemma involucratum Hemsl. The aqueous fraction of Bearded Argostemma may be a possible new option for the treatment of bacterial infections.

Anti-Bacterial Agents↗
PubMed1981

Biological and phytochemical investigation of plants XVI: Strumpfia maritima (Rubiaceae).

An aqueous extract of the flowering tops of Strumpfia maritima exhibited antifertility activity in female rats. The extract also contained the flavonol glycoside narcissin. This article represents the first reported isolation of this flavonoid from the Rubiaceae, as well as the first reported phytochemical and pharmacological investigation of the genus Strumpfia.

Animals↗
PubMed2002

Antitubercular constituents from the hexane fraction of Morinda citrifolia Linn. (Rubiaceae).

A crude ethanol extract and hexane fraction from Morinda citrifolia Linn. (Rubiaceae) show antitubercular activity. The major constituents of the hexane fraction are E-phytol, cycloartenol, stigmasterol, beta-sitosterol, campesta-5,7,22-trien-3beta-ol and the ketosteroids stigmasta-4-en-3-one and stigmasta-4-22-dien-3-one. E-Phytol, a mixture of the two ketosteroids, and the epidioxysterol derived from campesta-5,7,22-trien-3beta-ol all show pronounced antitubercular activity.

Antitubercular Agents↗
PubMed1995

Comparison of the evolution of ribulose-1, 5-biphosphate carboxylase (rbcL) and atpB-rbcL noncoding spacer sequences in a recent plant group, the tribe Rubieae (Rubiaceae).

Plastid sequences of the atpB-rbcL spacer and rbcL gene itself were used to evaluate their respective potential in reconstructing the phylogeny of 15 taxa from the tribe Rubieae (Rubiaceae). From our previous analyses using the atpB-rbcL spacer, the 15 selected taxa represent most of the variability of the tribe. Since this group is considered to be relatively recent (Upper Tertiary), it should allow the study of early dynamics of nucleotide substitutions in recent divergences. The results show that the spacer and rbcL inferred phylogenies are not totally congruent; the spacer trees are more similar to interpretations of morphological data. A comparative analysis of the pattern of nucleotide substitution of these two sequences in the Rubieae shows that (1) the overall rate of substitution is similar in the spacer and in rbcL, and the rate of synonymous substitution in rbcL is much higher; (2) the level of homoplasy is higher in rbcL than in the spacer matrix which shows a higher phylogenetic structure; and (3) the pattern of transition and transversion substitutions is different in the two sequences, and is not linear in rbcL. As a result of these observations, we suggest that (1) the spacer is evolving relatively slowly because of unsuspected, and phylogenetically important, selective constraints on its sequence; and (2) in the rbcL sequence, many sites, free of constraint, are changing at high rate, and some of these sites seem to have undergone multiple substitutions even in this recent tribe. This could explain the high level of homoplasy found in Rubieae rbcL sequences.

Base Sequence↗
PubMed2000

Morphology and ultrastructure of orbicules in the subfamily Ixoroideae (Rubiaceae).

Orbicules were studied in 43 species belonging to 32 genera of the five tribes of the Ixoroideae (Rubiaceae). The orbicules were investigated with scanning electron microscopy (SEM), light microscopy (LM), and transmission electron microscopy (TEM). Orbicules are present in all species investigated of the tribes Pavetteae, Octotropideae and Coffeeae. In the tribes Gardenieae and Aulacocalyceae orbicules were found in some species, while they were absent in others. 15 species out of 11 genera lack orbicules. Three orbicule types (III, V, and VI) could be distinguished, mainly on the basis of general morphological and ultrastructural variations. Orbicules that belong to type III (0.50-1.29µm) have perforations in their wall, a regular or irregular shape and two or three electron transparent cores. This orbicule type, exclusively found in all Pavetteae species investigated, can be divided into two subtypes. Orbicules of subtype IIIa are present in all genera related to Ixora, and orbicules of subtype IIIb in those genera related to Tarenna. Orbicules of type V (0.97-1.86µm) are present in Himalrandia tetrasperma (Aulacocalyceae), and in all Octotropideae genera investigated, except Feretia. Complexes of more than three individual orbicules characterize this type. They are irregularly shaped and have many perforations as well as sporopollenin granules on the orbicule wall. In all species investigated of tribe Coffeeae, type VI orbicules (0.56-1.60µm) are present. These orbicules are characterized by their embedded position towards the tapetal membrane, their aggregated form and by the presence of perforations as well as sporopollenin granules on their orbicule wall. In the tribe Gardenieae different types of orbicule were found (V, VI and orbicules that cannot be classified in our typology). Our results suggest that orbicule characters in the Ixoroideae may be systematically useful on tribal level.

Journal Article↗
PubMed1998

In vitro antiplasmodial activity of stem and root extracts of Nauclea latifolia S.M. (Rubiaceae).

Aqueous extracts from Nauclea latifolia S.M. (Rubiaceae), a plant commonly used in Ivory Coast by traditional healers for the treatment of malaria, were tested on two strains of Plasmodium faliparum: FcB1-Colombia (chloroquine-resistant) and a Nigerian strain (chloroquine-sensitive). The extracts were obtained from stems and roots of the plant in two forms, infusion and decoction, both methods used by most traditional healers. The in vitro activity of N. latifolia extracts on P. falciparum was assessed both visually and by a radioactive method. The visual analysis allowed determination of the time of extract action on the erythrocytic cycle, as well as the parasitic stage of most inhibitory effect. Similar results were obtained applying fresh, frozen or lyophilized extracts. The IC50 values determined were within the range already reported for other antimalarial plants such as Azadirachta indica A. Juss (Meliaceae) or Artemisia annua L. (Asteraceae). Aqueous extracts of N. latifolia inhibited P. falciparum (FcB1 strain) mainly at the end of the erythrocytic cycle (32nd to 48th hour).

Animals↗
PubMed1994

Identification of adducts formed by reaction of purine bases with a mutagenic anthraquinone, lucidin: mechanism of mutagenicity by anthraquinones occurring in rubiaceae plants.

A mutagenic anthraquinone, lucidin (1), occurring in Rubiaceae plants, reacted with nucleic bases under physiological conditions to form adducts. The order of the reactivity is as follows: adenine > guanine >> pyrimidine bases approximately 0. By spectroscopic analyses, the isolated purine base adducts were identified as condensed reactants at the benzylic position of 1 with a nitrogen atom of a purine base. The results indicate a strong possibility of the formation of an exomethylenic compound as an electrophile intermediate.

Anthraquinones↗
PubMed1996

Indonesian Medicinal Plants. XIV. Characterization of 3'-O-Caffeoylsweroside, a new secoiridoid glucoside, and kelampayosides A and B, two new phenolic apioglucosides, from the bark of Anthocephalus chinensis (Rubiaceae).

A new secoiridoid glucoside named 3'-O-caffeoylsweroside (1), and two new phenolic apioglucosides, named kelampayoside A (4) and kelampayoside B (6), together with eleven known compounds (five iridoids and six alkaloids), were isolated from the bark of Anthocephalus chinensis (Rubiaceae), an Indonesian medicinal plant from Sumatra Island, Indonesia. The chemical structures of 1, 4 and 6 have been elucidated respectively as 3'-O-caffeoylsweroside (1), antiarol 1-O-beta-D-apiofuranosyl (1 --> 6)-beta-D-glucopyranoside (4), and antiarol 1-O-beta-D-5"-O-caffeoylapiofuransoyl (1 --> 6)-beta-D-glucopyranoside (6) on the bases of their chemical and physiochemical properties. Among fourteen constituents characterized, cadambine (13), one of the major indole alkaloid constituents of A. chinensis, was shown to exhibit moderate growth-inhibitory activity against the malarial parasite Plasmodium falciparum (a chloroquine-resistant K1 strain) cultured in human erythrocytes.

Animals↗
PubMed2000

Phylogeny of the Neotropical Alibertia group (Rubiaceae), with emphasis on the genus Alibertia, inferred from ITS and 5S ribosomal DNA sequences.

Phylogenetic relationships of 38 species of the Alibertia group (Rubiaceae) and two outgroup species were investigated using the nuclear ribosomal 5S nontranscribed spacer (5S-NTS) and the internal transcribed spacers (ITS). Analysis of the data sets separately and in combination resulted in several well-supported and congruent groupings. However, the three analyses yielded different results as to the branching order of the basal clades. With the exception of Alibertia hispida, the species in the genus Alibertia appear in one weakly to moderately supported clade. This clade is in turn composed of two strongly supported subclades. One comprises several Alibertia species, including the type (A. edulis), three Borojoa species, and Randia tessmannii. The other subclade consists of Alibertia species only. This division is also generally supported morphologically by fruit size, corolla size, number of corolla lobes, and pollen aperture (porate vs. colporate). The sister group to the Alibertia clade comprises Duroia with Amaioua species internested. The close relationship of Ibetralia and Kutchubaea is corroborated. In addition, Alibertia hispida is a member of this strongly supported clade. Likewise, the two "Genipa" species are supported as a monophyletic group in 100% of the bootstrap replicates. It is concluded that the 5S spacer is superior to the commonly used ITS region in terms of resolution and robustness among closely related taxa.

Journal Article↗
PubMed2000

Combined phylogenetic analysis in the Rubiaceae-Ixoroideae: morphology, nuclear and chloroplast DNA data.

Parsimony analyses of morphology, restriction sites of the cpDNA, sequences from the nuclear, ribosomal internal transcribed spacer (ITS), and the chloroplast gene rbcL were performed to asses tribal and generic relationships in the subfamily Ixoroideae (Rubiaceae). The tribes Vanguerieae and Alberteae (Antirheoideae) are clearly part of Ixoroideae, as are some Cinchonoideae taxa. Pavetteae should exclude Ixora and allies, which should be recognized as the tribe Ixoreae. Heinsenia, representing Aulacocalyceae, is part of Gardenieae, as is Duperrea, a genus earlier placed in Pavetteae. Posoqueria and Bertiera and the taxa in the subtribe Diplosporinae should be excluded from Gardenieae. Bertiera and three Diplosporinae taxa are part of Coffeeae, while Cremaspora (Diplosporinae) is best housed in a tribe of its own, Cremasporeae. The mangrove genus Scyphiphora, recently placed in Diplosporinae, is closer to Ixoreae and tentatively included there. The combined analysis resulted in higher resolution compared to the separate analyses, exemplifying that combined analyses can remedy the incapability of one data set to resolve portions of a phylogeny. Twenty-four new rbcL sequences representing all five Ixoroideae tribes (sensu Robbrecht) are presented.

Journal Article↗
PubMed2001

Population-level variation in the expression of heterostyly in three species of Rubiaceae: does reciprocal placement of anthers and stigmas characterize heterostyly?

Heterostyly (i.e., reciprocal placement of anthers and stigmas between two or three floral morphs) is hypothesized to enhance outcrossing and reduce selfing. However, few studies have documented reciprocity among individual plants; instead, mean anther and stigma heights for floral morphs are usually reported, masking interindividual variation. We measured eight floral dimensions for individuals in five populations of three heterostylous Rubiaceae. The three methods used to quantify reciprocity yielded different conclusions regarding the degree to which populations conformed to expectations for heterostylous plants. Only Psychotria poeppigiana had stigma and, to a lesser degree, anther heights in discrete classes. Variation among plants of Bouvardia ternifolia and Psychotria chiapensis yielded a continuum of anther and stigma heights across populations. Comparison of distances between stigma and anthers indicated that only flowers of B. ternifolia had, as expected, a constant value for this distance. Finally, regression relationships between anther and stigma heights and corolla length showed that only in one population each of B. ternifolia and P. poeppigiana, and in P. chiapensis, was distance between anthers and stigmas the same across the range of corolla sizes for both floral morphs. Variation among these species in expression of heterostyly was not clearly linked to phylogenetic relationship or pollinator syndromes. Two approach herkogamous (AH) species were studied for comparison. Flowers of Psychotria brachiata were consistently AH, but flowers of P. pittieri were highly variable. Determining fitness consequences of population-level variation in sexual systems requires studies linking floral morphology to pollinator behavior and pollen transfer.

Journal Article↗
PubMed2003

Reconstructing ancestral patterns of colonization and dispersal in the Hawaiian understory tree genus Psychotria (Rubiaceae): a comparison of parsimony and likelihood approaches.

Systematic and biogeographical relationships within the Hawaiian clade of the pantropical understory shrub genus Psychotria (Rubiaceae) were investigated using phylogenetic analysis of 18S-26S ribosomal DNA internal (ITS) and external (ETS) transcribed spacers. Phylogenetic analyses strongly suggest that the Hawaiian Psychotria are monophyletic and the result of a single introduction to the Hawaiian Islands. The results of phylogenetic analyses of ITS and ETS partitions alone give slightly different topologies among basal lineages of the Hawaiian clade; however, such differences are not well supported. Relationships in the section Straussia clade in particular are not well resolved because of few nucleotide changes on internal branches, suggesting extremely rapid radiation in the lineage. Parsimony and likelihood reconstructions of ancestral geographical distributions using the topologies inferred from both parsimony and likelihood analysis of combined data and using different combinations of models and branch lengths gave highly congruent results. However, for one internal node (corresponding to the majority of the "greenwelliae" clade), parsimony reconstructions were unable to distinguish between three possible island states, whereas likelihood reconstructions resulted in clear ordering of possible states, with the island of Oàhu slightly more probable than other islands under all but one model and branch length combination considered (the Jukes-Cantor-like model with branch lengths inferred under parsimony, under which conditions Maui Nui is more probable). A pattern of colonization from oldest to youngest islands was inferred from the phylogeny, using maximum parsimony and maximum likelihood. Additionally, a much higher incidence of intraisland versus interisland speciation was inferred.

Base Sequence↗