Psychotria Species Research Articles

Identification of the bacterial endosymbionts in leaf nodules of Pavetta (Rubiaceae)

Three genera in the Rubiaceae (Pavetta, Psychotria and Sericanthe) harbour bacterial endosymbionts within leaf nodules or galls. The present paper identifies the bacterial endophytes in three leaf-nodulating Pavetta species. In order to reveal their identity and assess their phylogenetic position, 16S rRNA, recA and gyrB genes were sequenced from an extensive sampling of Burkholderia strains. This multigene approach results in a robust phylogeny, which places the bacterial endosymbionts of Pavetta at two distinct positions within the genus Burkholderia (class Betaproteobacteria), suggesting that leaf-nodulating endosymbionts within Pavetta have different origins. The endophytes of nodulated Psychotria species were recognized as the closest relatives to the Pavetta endosymbionts. Our results suggest that the endosymbionts of Pavetta represent novel species, which can be classified as 'Candidatus Burkholderia hispidae', 'Candidatus Burkholderia rigidae' and 'Candidatus Burkholderia schumannianae'.

Comparative leaf anatomy and micromorphology of Psychotria species (Rubiaceae) from the Atlantic Rainforest

The genus Psychotria comprises approximately 2,000 species that are mostly shrubs distributed in forests of the tropics and subtropics. Within the Rubiaceae, Psychotria is well known for its species that produce bioactive alkaloids and for its taxonomic complexity. The anatomical and micromorphological characters of the leaves of P. hoffmannseggiana, P. carthagenensis, P. deflexa, P. glaziovii, P. leiocarpa, P. racemosa, and P. vellosiana were investigated and described to understand the interspecific variation of these species, which will contribute to the systematics of the genus. Principal component analysis (PCA) and unweighted pair group method analysis (UPGMA) indicated four groups based on the presence or absence of some of the characters studied. Dorsiventral mesophyll, hypostomatic leaves, paracytic stomata, organization of the vascular system of the petiole and midrib in an arc and the presence of accessory bundles are common in the species examined and are typical characteristics of the Rubiaceae. The presence of styloid crystals and alkaloids are considered diagnostic characters of Psychotria. Other characteristics used to separate species in the genus are the petiole contour, cuticle ornamentation, and presence of trichomes. The results of the UPGMA cluster analyses indicated that there is similarity between Psychotria (subg. Heteropsychotria) and Palicourea species.

Antimycobacterial Activity and Alkaloid Prospection ofPsychotriaSpecies (Rubiaceae) from the Brazilian Atlantic Rainforest

Ten Psychotria species were collected in two fragments of Atlantic Forest in Rio de Janeiro: Psychotria pubigera (P1A and B), P. ruelliifolia (P2), P. suterela (P3), P. stachyoides (P4), P. capitata (P5), P. glaziovii (P6), P. leiocarpa (P7), P. nuda (P8), P. racemosa (P9) and P. vellosiana (P10). Ethanol extracts of these species were evaluated for their antimycobacterial activity, in an attempt to find new antituberculosis agents. Psychotria pubigera (P1A), P. ruelliifolia (P2) and P. stachyoides (P4) were the most active against Mycobacterium. The anti-inflammatory potential of these extracts was also evaluated in vitro to learn if they inhibit nitric oxide (NO) production in macrophages and if they have free-radical scavenging properties, because inflammation is a severe problem caused by tuberculosis, especially when the infection is from M. bovis or M. tuberculosis. Psychotria suterela (P3), P. stachyoides (P4) and P. capitata (P5) were the most active in inhibiting macrophage NO production but they were not the most antioxidant species. This suggests that NO inhibitory activity is not due to the scavenging of NO generated but due to a specific inhibition of iNOS activity or expression. In addition, cytotoxicity was tested in the macrophages (the host cells of the Mycobacterium) and it was verified that the extracts selectively killed the bacteria and not the host cells. When analyzing antimycobacterial, cytotoxicity and NO inhibitory activities in combination, P. stachyoides (P4) was the most promising anti-TB extract tested. Further, indol alkaloids were detected in P. suterela and P. nuda, and 5,6-dihydro-β-carboline alkaloids in all of the species studied, with the highest amounts found in P. capitata and P. racemosa.

Karyotype characterisation of Brazilian species of the genus Psychotria L. — subfamily Rubioideae (Rubiaceae)

The pantropical genus Psychotria L., probably the largest among angiosperms, occurs in different Brazilian vegetal formations. This work determined the chromosome numbers and karyotypic characteristics of ten species of Brazilian Psychotria. The chromosome numbers ranged from 2n = 22, in five species (P. hoffmannseggiana (Willd. ex Roem. & Schult.) Mull. Arg., P. lupulina Benth., P. marginata Sw., P. tenerior (Cham.) Mull. Arg., and P. trichophora Mull. Arg.), to 2n = 40, in P. mapourioides DC., and 2n = 44 in four other species (P. carthagenensis Jacq., P. gracilenta Mull. Arg., P. longipes Mull. Arg. and P. suterella Mull. Arg.). In addition to these differences, great variations in chromosome lengths and karyotypic formulae were also observed among these species. Chromosome length varied from 5.59 μm to 0.90 μm and no relationship was detected between chromosome numbers and lengths in any species. Chromosomes are principally metacentric, except for P. mapourioides that presents mainly submetacentric chromosomes. Karyotypic asymmetry rate (TF%) ranged from moderate (TF% = 38.83) to highly symmetric (TF% = 50.00). The difference in chromosome numbers of Psychotria carthagenensis (2n = 44) and P. mapourioides (2n = 40) is very important to taxonomists, because these have great difficulty in identifying and differentiating these two species with the sole use of morphological characteristics, since some individuals have intermediate characteristics between both species. Although this study does not allow for a consistent cytotaxonomic analysis, not even to delimit P. subgen. Psychotria and P. subgen. Heteropsychotria, this karyotype analysis of some Brazilian species, along with their morphology, may contribute to a better knowledge of the genus.

Bark and wood anatomy of the Tribe Hamelieae (Rubiaceae)

We studied wood and bark anatomy of six (Deppea, Hamelia, Hoffmannia, Omiltemia, Pinarophyllon, and Plocaniophyllon) of the seven genera of the tribe Hamelieae sensu Robbrecht, and Syringantha with as main purposes to determine if there are characters that support the boundaries of the Hamelieae, to evaluate the status of Syringantha as a member of the Hamelieae, and to evaluate the taxonomic position of Hamelieae within the subfamilies Rubioideae or Cinchonoideae. In addition, we studied for comparative purposes representative species of Psychotria (Psychotrieae, Rubioideae), Exostema, and Hintonia (Portlandia group, Cinchonoideae), Randia (Gardenieae, Ixoroideae), and Bouvardia (incertae sedis). Bark of most genera studied had a single periderm, while a rhytidome was observed in Exostema and few species of Psychotria. The mineral inclusions allowed recognizing related genera, for example, raphides in Hamelieae and Psychotria, prisms in Exostema, and druses in Randia. Members of Hamelieae showed wood type II, distinctive by the occurrence of libriform septate fibres, vessels in radial multiples of 2–6 vessels (80–90%, vessel grouping index 1.79–2.74), and diffuse apotracheal parenchyma. Syringantha shares with members of Hamelieae the presence of an endodermis, raphides in the bark, and wood type II. The combination of other wood characters mainly lend quantitative support to the taxonomic delimitation of some genera within Hamelieae. Raphides and wood type II supported a close relationship between Hamelieae and Hillieae within Cinchonoideae; characters that distinguish them from the other members of Cinchonoideae. Our results suggest independent origins of wood type II within the Rubiaceae. In addition, vessel density and diameter are discussed as possible adaptations to the different forest types where members of Hamelieae occur.

Bioactive Alkaloids from South American Psychotria and Related Species

Many important molecules have been discovered from tropical and sub-tropical plant biodiversity. However, the largest part of the chemical profile of such biodiversity remains unknown. Combining ethnopharmacological and chemotaxonomical investigation can be a good strategy in bioactive compound discovery. South American Psychotria species studied by this approach proved to be a rich source of new bioactive alkaloids, some of which bear unique chemical skeletons.

Extracts affecting mitotic division in root-tip meristematic cells

Some species of Psychotria (Rubiaceae) are important in herbal medicine, where their extracts are used internally for infections of the female reproductive system, bronchitis, gastrointestinal disturbances, skin irritations, tumors, ulcers, and eye disturbances. The antiproliferative and genotoxic effects of Psychotria myriantha Mull. Arg. and P. leiocarpa Cham. et Schlecht infusions on the Allium cepa L. cell cycle were evaluated. The teas were prepared by infusing the leaves in distilled water, in two concentrations: 1.13 mg/mL and 6.78 mg/mL. Three groups of four bulbs were used for each Psychotria species. After the bulbs rooted in distilled water, they were transferred to the teas for 24 hours, except for the control that stayed in water. The rootlets were then collected, fixed in ethanol-acetic acid (3:1) for 24 hours, and stored in 70% ethanol. For each group of bulbs, 4000 cells were analyzed, calculating the mitotic indexes, submitting them to statistic analysis, using the χ 2 test (p = 0.05). The results showed a decrease in mitotic index with an increase in tea concentration in both species. In P. leiocarpa, the mitotic index values differed significantly between the control and concentration of 6.78 mg/mL (χ 2 = 9.863). For P. myriantha, the values referring to the mitotic index differed greatly between the control and the treatments (χ 2 = 124.8). With this study, it was determined that P. myriantha and P. leiocarpa infusions possess antiproliferative effects on the A. cepa cell cycle, and teas of P. myriantha also have genotoxic activity.

Four new submontane species of Psychotria (Rubiaceae) with bacterial nodules from Western Cameroon

Four new Psychotria species with conspicuous bacterial nodules in their leaf-blades, P. njumei Cheek, P. ngollengollei Cheek, P. darwiniana Cheek and P. babatwoensis Cheek are described, mapped and illustrated from the submontane forests of the Cameroon Highlands. Their taxonomic and conservation status are assessed.

Reproductive ecology of 21 coexisting Psychotria species (Rubiaceae): when is heterostyly lost?

Heterostyly is a genetic polymorphism in which plant populations are composed of two or more morphs that differ in stigma and anther heights. The polymorphism promotes intermorph pollen transfer, thus outcrossing. Heterostyly has been reported in 28 angiosperm families and is frequently lost in heterostylous lineages. To assess ecological factors related to shifts from heterostyly to monomorphy, we examined the reproductive ecology of heterostylous tropical shrubs of Psychotria. Among 21 species at Barro Colorado Island and the nearby Parque Nacional Soberania, Panama, 14 species were heterostylous while seven were monomorphic. A molecular phylogeny and the existence elsewhere of heterostylous populations indicated that the breakdown of heterostyly had occurred independently. Heterostylous and monomorphic species were visited by the same bee species, although visit frequencies were lower in monomorphic species. Monomorphic species had significantly lower population density and greater fruit set than did heterostylous species. Autonomous autogamy made a large contribution to fruit set in monomorphic species and was only rarely observed in heterostylous species. The results indicate monomorphic and heterostylous species produce more seeds through selfing and outcrossing, respectively. The limitation of outcrossing as a result of low population density may be related to the breakdown of heterostyly and the evolution of selfing. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 125‐134. ADDITIONAL KEYWORDS: Barro Colorado Island ‐ breeding system evolution ‐ Panama ‐ pollination ‐ rarity ‐ self-fertilization ‐ tropical forest.

Metabolic engineering of cell cultures versus whole plant complexity in production of bioactive monoterpene indole alkaloids: Recent progress related to old dilemma

Monoterpene indole alkaloids (MIAs) are a large class of plant alkaloids with significant pharmacological interest. The sustained production of MIAs at high yields is an important goal in biotechnology. Intensive effort has been expended toward the isolation, cloning, characterization and transgenic modulation of genes involved in MIA biosynthesis and in the control of the expression of these biosynthesis-related genes. At the same time, considerable progress has been made in the detailed description of the subcellular-, cellular-, tissue- and organ-specific expressions of portions of the biosynthetic pathways leading to the production of MIAs, revealing a complex picture of the transport of biosynthetic intermediates among membrane compartments, cells and tissues. The identification of the particular environmental and ontogenetic requirements for maximum alkaloid yield in MIA-producing plants has been useful in improving the supply of bioactive molecules. The search for new bioactive MIAs, particularly in tropical and subtropical regions, is continuously increasing the arsenal for therapeutic, industrially and agriculturally useful molecules. In this review we focus on recent progress in the production of MIAs in transgenic cell cultures and organs (with emphasis on Catharanthus roseus and Rauvolfia serpentina alkaloids), advances in the understanding of in planta spatial-temporal expression of MIA metabolic pathways, and on the identification of factors capable of modulating bioactive alkaloid accumulation in nontransgenic differentiated cultures and plants (with emphasis on new MIAs from Psychotria species). The combined use of metabolic engineering and physiological modulation in transgenic and wild-type plants, although not fully exploited to date, is likely to provide the sustainable and rational supply of bioactive MIAs needed for human well being.

Potential bird dispersers of Psychotria in a area of Atlantic forest on Ilha Grande, RJ, Southeastern Brazil: a biochemical analysis of the fruits

The present study assessed the fruiting pattern, bird foraging behavior, and sugar content of ripe fruits of two sympatric species of Rubiaceae (Psychotria brasiliensis and P. nuda). This study was carried out in an Atlantic forest area on Ilha Grande, RJ, between August 1998 and July 1999. Fruit production occurred year round, with a peak of mature P. brasiliensis fruits in December 1998 and another of P. nuda in February of 1999. Lipaugus lanioides (Cotingidae), Baryphtengus ruficapillus (Momotidae) and Saltator similis (Emberizidae) made the most frequent foraging visits to fruiting P. brasiliensis, so that L. lanioides and B. ruficapillus removed the fruits with sallying maneuvers while S. similis gleaned the fruits. Lipaugus lanioides was by far the most important consumer, and potentially the main disperser of P. brasiliensis. Birds of this genus are heavy frugivores in the tropical forests and are widely assumed to be important seed dispersers. The fruits were analyzed quantitatively and qualitatively in relation to the amounts of sucrose and starch. Psychotria brasiliensis (the visited species) showed the smallest quantity of sucrose and the highest amount of starch. These findings suggest that what may influence the birds' choice of fruit is the proportion of starch in the Psychotria species studied here rather than the carbohydrate composition.

Taxonomy and conservation of the genus Psychotria (Rubiaceae) in S.Tomé e Príncipe (Gulf of Guinea)

A revision of the species of Psychotria from S.Tome e Principe is presented, including a key to the species, full descriptions, distribution, conservation status, notes and specimens examined. Twelve species occur on the islands of S.Tome and Principe; seven are endemic, six to S.Tome and one to Principe. One new species (P. exellii sp. nov.) is described from S.Tome. The conservation status of five endemic species is evaluated using IUCN guidelines/criteria and categories of threat are proposed. Two IUCN Red List endemics (P. guerkeana and P. grumilea) are re-evaluated and a different category of threat is proposed for P. grumilea. Three of the seven endemic species are considered Critically Endangered, one Endangered and three are Vulnerable, using the criteria for extinction threat set by the IUCN. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 147, 469–481.

Crown architecture in sun and shade environments: assessing function and trade‐offs with a three‐dimensional simulation model

Sun and shade environments place markedly different constraints on the photosynthetic performance of plants. Leaf-level photosynthetic responses to sun and shade have been extensively investigated, whereas there has been much less research on the functional role of crown architecture in these environments. This paper focuses on the role of architecture in maximizing light capture and photosynthesis in shaded understories and in minimizing exposure to excess radiation in open high light environments. Understanding these contrasting roles of architecture is facilitated by application of a three-dimensional structural-functional model, Y-plant. Surveys of understory plants reveal a diversity of architectures but a strong convergence at only modest light-capture efficiencies because of significant self-shading. Simulations with Psychotria species revealed that increasing internode lengths would increase light-capture efficiencies and whole plant carbon gain. However, the costs of the additional required biomechanical support was high, which, in terms of relative growth rates, would override the advantage provided by higher light-capture efficiencies. In high light environments, leaf angles and self-shading provide structural photoprotection, minimizing potential damage from photoinhbition. Simulations reveal that without these structural protections photoinhibition of photosynthesis is likely to be much greater with daily carbon gain significantly reduced.

Five New combinations and One New Name in Rubiaceae from South-East Asia

Five new combinations and one new name are proposed for six Rubiaceae species from South-East Asia. Four new combinations are proposed in Cyclophyllum and one in Psychotria; a new name is proposed for one Psychotria species.

‘Candidatus Burkholderia calva’ and ‘Candidatus Burkholderia nigropunctata’ as leaf gall endosymbionts of African Psychotria

Phylogenetic 16S rRNA gene analysis was used to assign the bacterial leaf-nodulating endosymbionts of two tropical African Psychotria species to the genus Burkholderia. The microsymbionts of the different Psychotria hosts were recognized as distinct and novel species of Burkholderia on the basis of relatively low intersequence similarities and sufficiently large evolutionary distances when compared with each other and their closest validly named neighbours. The obligate endosymbiotic nature of the bacteria prevented their in vitro cultivation and the deposition of type strains to culture collections. Therefore, the provisional status Candidatus is assigned to the bacterial partners of Psychotria calva and Psychotria nigropunctata, with the proposal of the names 'Candidatus Burkholderia calva' and 'Candidatus Burkholderia nigropunctata', respectively.

Taxonomic significance of alkaloids and iridoid glucosides in the tribe Psychotrieae (Rubiaceae)

Leaves of 15 Brazilian species of Psychotria, three of Rudgea and Palicourea rigida, were analyzed for their alkaloid and iridoid content. Alkaloids were found in three of Rudgea and 14 species of Psychotria, and iridoids were found in Psychotria leiocarpa, which produces asperuloside and deacetylasperuloside. Palicourea rigida yielded no alkaloids but loganin was isolated. The results illustrate the significance of the alkaloids in the chemotaxonomy of some taxa of Psychotrieae. The phytochemical data indicate that the American species of Psychotria with Palicourea could be joined to form the genus Heteropsychotria.

A functional analysis of the crown architecture of tropical forest Psychotria species: do species vary in light capture efficiency and consequently in carbon gain and growth?

The crown architectures of 11 Psychotria species native to Barro Colorado Island, Panama were reconstructed from field measurements of leaf and branch geometry with the three-dimensional simulation model Y-plant. The objective was to assess the role of species differences in architecture in light capture and carbon gain in their natural understory environment. When species were grouped according to their putative light environment preference, the shade tolerant species were found to have a small but significantly higher efficiency of light capture for both diffuse and direct light as compared to the light demanding species. Within each grouping, however, there were few significant differences in light capture efficiency among species. The lower efficiencies of light demanding species was due to slightly higher self-shading and slightly lower angular efficiencies. Simulations of whole plant assimilation showed that light demanding species had greater daily assimilation in both direct and diffuse light due to the significantly greater light availability in the sites where light demanding species were found, as compared to those where shade tolerant species occurred. Among light demanding species, the above ground relative growth rate measured over a 1-year period by applying allometric equations for mass versus linear dimensions, was positively correlated with diffuse PFD and with mean daily assimilation estimated from Y-plant. For the shade tolerant plants, there was no significant correlation between RGR and mean daily assimilation or with any measure of light availability, probably because they occurred over a much narrower range of light environments. Overall, the results reveal a strong convergence in light capture efficiencies among the Psychotria species at lower values than previously observed in understory plants using similar approaches. Constraints imposed by other crown functions such as hydraulics and biomechanical support may place upper limits on light capture efficiency.

SEED MASS AND SEEDLING PERFORMANCE WITHIN EIGHT SPECIES OF PSYCHOTRIA (RUBIACEAE)

Large seeds have been hypothesized to confer survival advantages in the shaded forest, and small seeds to confer growth advantages in open habitats. We explored these hypotheses using experimental studies in both field and controlled conditions. Our experiments examined intraspecific effects of seed mass on seedling demography in eight sympatric woody species of Psychotria. We compared the effects of seed mass on seedling size (biomass), maximum relative growth rate (RGR), the proportion of emerged seedlings that survived until one year of age, and the proportion of sown seeds reaching the stage of one-year-old seedlings in gaps compared with shaded rain forest habitats, as well as in contrasting greenhouse light conditions. For each species, seeds were classified into four seed mass categories and introduced to three pairs of shaded forest gap sites. In the greenhouse, emerged seedlings from different seed mass categories were grown in contrasting light environments. A positive effect of seed mass on see...

Two New Species of Psychotria (Rubiaceae) from Western Cameroon

first one described here, were later found in other areas of forest around Mt Cameroon, but the remainder, for example the second species, have not been located elsewhere and appear to be local endemics, perhaps once more widespread in the eastern foothill forests. A checklist of the flora of Mt Cameroon and its adjoining foothills was recently published (Cable & Cheek 1998). Within the BonadikombeBimbia forest, a grid of paths ("transects") was set up along which most of the specimens cited were collected, allowing exact locations to be given. The system of naming of these transects (e.g. "SBLW 1190 m") is explained in Cheek (1992). The genus Psychotria was revised for Africa by Petit (1964, 1966). He recognized 161 species. Diversity of Psychotria species in Africa is at its highest in the GuineoCongolian region, with 69 species in the Flora of Tropical West Africa area alone (Hepper 1963). Four new species of Psychotria were identified during botanical inventories around Mt Cameroon. The two described here are particularly distinct and are also represented by abundant material.

Notes on some South American species of Psychotria subgenus Heteropsychotria (Rubiaceae), with observations on rubiaceous taxonomic characters

During the preparation of a treatment of the Rubiaceae for theGuide to the Vascular Plants of Central French Guiana, several field and laboratory observations have contributed toward a better understanding of the morphological variation of certain species ofPsychotria and have stimulated a reevaluation of some morphological features used by previous authors in distinguishing taxa in thePsychotria. Typification for all taxa is provided, several new synonyms and one new combination,Psychotria carapichea (Poir.) Delprete, are proposed, and illustrations ofP. ligularis andP. carapichea are included.