LC-MS/MS Screening, Total Phenolic, Flavonoid and Antioxidant Contents of Crude Extracts from Three Asclepiadaceae Species Growing in Jordan

This study aimed to evaluate the antioxidant activity and total phenolic content (TPC) and total flavonoid content (TFC) of crude extracts obtained from three Asclepiadaceae species, namely, Calotropis procera L., Peruglaria tomentosa L., and Pentatropis spiralis (Forsk.) Decne. Both butanol and aq. methanol extracts of the three species showed the highest amount of phenol and flavonoid contents, which exhibited the greatest antioxidant activity in the scavenging of 2,2-diphenyl-2-picrylhydrazyl free radical (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS), ferrous chelating effect (FIC), and hydroxyl radical (HDR) assays. Phytochemical screening of the extracts revealed the presence of alkaloids, tannins, sponins, flavonoids, terpenoids, and glycosides. LC-MS analysis was carried out to identify the major compounds from each crude extract. A total of 12 phenolic compounds in the extracts of the 3 species were identified and quantified, including 9 flavonoids, 2 hydroxybenzoic acids, and 3 hydroxycinnamic acids. The current study also revealed a good correlation between total phenolic contents and the observed antioxidant activity of the crude extracts.

The impact of carbon source on cell growth and the production of bioactive compounds in cell suspensions of Hancornia speciosa Gomes

Belonging to the Brazilian flora, the species Hancornia speciosa (Gomes), known as mangabeira, has bioactive compounds of interest, such as flavonoids, xanthones, and proanthocyanidins. The objective of this study was to determine how the supplementation of sugars in culture medium affects the osmotic potential of the medium, as well as its influence on cell growth and on the concentration of phenolic compounds. For this purpose, after 90 days of subculture, 20 mL aliquots of the cultures were added to flasks containing 20 mL of medium with different sugars (glucose, fructose, sucrose, mannitol, and sorbitol) under a 16-h photoperiod with a spectral range between 400 and 700 nm of photosynthetically active radiation (45-55 μmol m-2 s-1) in a shaker at 110 rpm. After 30 days, the pH, electrical conductivity, osmotic potential, biomass accumulation, and concentrations of phenolic compounds were evaluated. Regardless of their concentration in the medium, the sugars sorbitol and mannitol provided more unfavorable conditions for water absorption at the cellular level, reducing the water potential of the medium. Sucrose favored greater water absorption and biomass accumulation. Among the various sugar concentrations, 3% (30 g/L) sucrose or glucose improved the accumulation of fresh and dry cell weight and the production of polyphenols such as chlorogenic acid, epicatechin, rosmarinic acid, hesperidin, rutin, and quercetin. In addition, they resulted in a higher osmotic potential of the medium and larger cells than other carbon sources. Despite the differences in cell size, no culture conditions compromised cell survival.

Decalepis salicifolia (Bedd. ex Hook. f.) Venter: A steno-endemic and critically endangered medicinal and aromatic plant from Western Ghats, India

Decalepis salicifolia (Bedd. ex Hook. f.) Venter is a potential medicinal and highly aromatic plant species confined to the southernmost part of the Western Ghats of India. The plant is well known for its traditional uses among the various tribal communities of south India. The tubers of the plant possess characteristic vanillin-like aroma due to the presence of the compound 2-hydroxy-4-methoxybenzaldehyde. The tubers are used to substitute Hemidesmus indicus in various herbal formulations. The plants in the wild are continuously uprooted for their roots, leading to the irreversible destruction of the whole plant. The resulting tremendous loss of populations in the wild led to the species being declared as critically endangered by IUCN. Our group is working on the various aspects of this species including population status, distribution mapping, prospection, and conservation management. In the present review, we have brought out the available information till date on D. salicifolia, including taxonomy, ethno-medicinal uses, phytochemistry, pharmacology, population status, and conservation efforts along with research gap and lacunae to provide direction for further research into this less explored medicinal and aromatic plant.

Testing the hypothesis of loss of defenses on islands across a wide latitudinal gradient of Periploca laevigata populations

PREMISE OF THE STUDY

We tested a hypothesis that predicts loss of chemical defenses on island plant populations (LCDIH) as an evolutionary response to limited herbivore pressures.

METHODS

Using a common garden approach, we grew 16 populations (N = 286 seedlings) of Periploca laevigata, a Mediterranean shrub for which previous studies suggested that animal browsing elicits defensive responses mediated by tannins. Our experimental setting represented a wide latitudinal gradient (37-15°N) encompassing three island systems, virtually free of large herbivores, and three mainland areas. Putative chemical defenses were estimated from tannin-protein precipitation assays, and inducible responses in growth and chemical traits were assessed between seasons and by subjecting plants to a pruning treatment.

KEY RESULTS

We failed to find support for the LCDIH, since island populations (Canary Islands, Cape Verde) had increasingly higher constitutive levels of tannins at lower latitudes. Seasonality, but not experimental pruning, induced variation in levels of tannins in a consistent pattern across populations. Thus, net differences in leaf tannin concentration remained similar among geographical areas regardless of the factor considered, with latitude being the best explanatory factor for this trait over seasonal growth patterns.

CONCLUSIONS

Geographical variation in total tannin pools appears to be mediated by factors other than herbivore pressure in P. laevigata. We hypothesize that abiotic correlates of latitude not considered in our study have promoted high constitutive levels of leaf tannins across Macaronesian populations, which ultimately may explain the pattern of seasonal variation and latitudinal increase from Mediterranean to subtropical Cape Verde populations.

Healing effects of Pergularia tomentosa L., a native medicinal plant in Bushehr province, Iran on burn, in animal model

Burn injury is one of the most destructive events in the world. The Pergularia tomentosa L. is a medicinal plant that traditionally, applies for treatment of burning, in Bushehr province, Iran. Various bioactive compounds such as steroid glycosides, tannins, various vitamins, saponins, cardenolides and anthraquinones were identified into extract of the plant, which can be effective in burn wound healing. Twenty-one rats weighting every one 200±5 grams were divided equally into three groups. The second-degree burning induced on all groups. One of groups did not receive any treatment (The control group) and was treated locally with saline and eucerin. The Second group received the P. tomentosa L. as a topical ointment, and the third group received locally, a thin layer of silver sulfadiazine ointment 3% after washing the wound with saline. Afterward treatment period, the microscopic slides from histological sections were prepared. At that point, amounts of the fibroblast cells, blood vessels, wound area, necrotic tissues, and diameter of epidermis rate of wound healing were determined. Also the exterior status of wound in different days was considered. Results obtained from current study have revealed that the extract of P. tomentosa L. can significantly, cause qualitative and quantitative acceleration in healing of second degree burn wounds, due to their bioactive and vasoactive properties. In conclusion the P. tomentosa L. can is used as an overborne medicine with lower cost and side effect than the similar chemical medicines. Although, the further studies are needed on these plants, due to their some toxic effects.

Biological Invasion Influences the Outcome of Plant-Soil Feedback in the Invasive Plant Species from the Brazilian Semi-arid

Plant-soil feedback is recognized as the mutual interaction between plants and soil microorganisms, but its role on the biological invasion of the Brazilian tropical seasonal dry forest by invasive plants still remains unclear. Here, we analyzed and compared the arbuscular mycorrhizal fungi (AMF) communities and soil characteristics from the root zone of invasive and native plants, and tested how these AMF communities affect the development of four invasive plant species (Cryptostegia madagascariensis, Parkinsonia aculeata, Prosopis juliflora, and Sesbania virgata). Our field sampling revealed that AMF diversity and frequency of the Order Diversisporales were positively correlated with the root zone of the native plants, whereas AMF dominance and frequency of the Order Glomerales were positively correlated with the root zone of invasive plants. We grew the invasive plants in soil inoculated with AMF species from the root zone of invasive (I _changed) and native (I _unaltered) plant species. We also performed a third treatment with sterilized soil inoculum (control). We examined the effects of these three AMF inoculums on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas. We found that I _unaltered and I _changed promoted the growth of all invasive plants and led to a higher plant dry biomass, mycorrhizal colonization, and P uptake than control, but I _changed showed better results on these variables than I _unaltered. For plant responsiveness to mycorrhizas and fungal inoculum effect on plant P concentration, we found positive feedback between changed-AMF community (I _changed) and three of the studied invasive plants: C. madagascariensis, P. aculeata, and S. virgata.

Evolution on the backbone: Apocynaceae phylogenomics and new perspectives on growth forms, flowers, and fruits

PREMISE OF THE STUDY

We provide the largest phylogenetic analyses to date of Apocynaceae in terms of taxa and molecular data as a framework for analyzing the evolution of vegetative and reproductive traits.

METHODS

We produced maximum-likelihood phylogenies of Apocynaceae using 21 plastid loci sampled from 1045 species (nearly 25% of the family) and complete plastomes from 73 species. We reconstructed ancestral states and used model comparisons in a likelihood framework to analyze character evolution across Apocynaceae.

KEY RESULTS

We obtained a well-supported phylogeny of Apocynaceae, resolving poorly understood tribal and subtribal relationships (e.g., among Amsonieae and Hunterieae, within Asclepiadeae), rejecting monophyly of Melodineae and Odontadenieae, and placing previously unsampled and enigmatic taxa (e.g., Pycnobotrya). We provide new insights into the evolution of Apocynaceae, including frequent shifts between herbaceousness and woodiness, reversibility of twining, integrated evolution of the corolla and gynostegium, and ancestral baccate fruits.

CONCLUSIONS

Increased sampling and selection of best-fitting models of evolution provide more resolved and robust estimates of phylogeny and character evolution than obtained in previous studies. Evolutionary inferences are sensitive to choice of phylogenetic frameworks and models.

In Vitro Callus Induction and Plant Regeneration from Stem Explants of Ceropegia noorjahaniae, a Critically Endangered Medicinal Herb

An efficient protocol has been developed for in vitro regeneration of a large number of plantlets of Ceropegia noorjahaniae Ansari via indirect organogenesis from stem explants excised from in vitro-germinated seedlings. The callus was efficiently induced from the stem explants using Murashige and Skoog (MS) medium supplemented with auxins and their combinations. The highest number of shoots (16.0 ± 0.2) and shoot length (5.5 ± 0.1 cm) was achieved when the callus was subcultured to MS medium supplemented with 6-benzylaminopurine, BAP (2.0 mg/l) and indole-3-acetic acid, IAA (0.2 mg/l). The in vitro-developed shoots were rooted well in half-strength MS medium supplemented with 1.0 mg/l of indole-3-butyric acid (IBA) and 0.3 mg/l of α-naphthalene acetic acid (NAA). The plantlets were successfully hardened with 82 % survival rate. This is the first report on the regeneration of plants through indirect shoot organogenesis from stem derived calli of C. noorjahaniae.

Development and evolution of extreme synorganization in angiosperm flowers and diversity: a comparison of Apocynaceae and Orchidaceae

BACKGROUND AND AIMS

Apocynaceae and Orchidaceae are two angiosperm families with extreme flower synorganization. They are unrelated, the former in eudicots, the latter in monocots, but they converge in the formation of pollinia and pollinaria, which do not occur in any other angiosperm family, and for which extreme synorganization of floral organs is a precondition. In each family extensive studies on flower development and evolution have been performed; however, newer comparative studies focusing on flower synorganization and involving both families together are lacking.

SCOPE

For this study an extensive search through the morphological literature has been conducted. Based on this and my own studies on flowers in various Apocynaceae and Orchidaceae and complex flowers in other angiosperms with scanning electron microscopy and with microtome section series, a review on convergent floral traits in flower development and architecture in the two families is presented.

KEY FINDINGS

There is a tendency of protracted development of synorganized parts in Apocynaceae and Orchidaceae (development of synorganization of two or more organs begins earlier the more accentuated it is at anthesis). Synorganization (or complexity) also paves the way for novel structures. One of the most conspicuous such novel structures in Apocynaceae is the corona, which is not the product of synorganization of existing organs; however, it is probably enhanced by synorganization of other, existing, floral parts. In contrast to synorganized parts, the corona appears developmentally late.

CONCLUSIONS

Synorganization of floral organs may lead to a large number of convergences in clades that are only very distantly related. The convergences that have been highlighted in this comparative study should be developmentally investigated directly in parallel in future studies.

The Impact of Global Climate Change on the Geographic Distribution and Sustainable Harvest of Hancornia speciosa Gomes (Apocynaceae) in Brazil

The global Climate change may affect biodiversity and the functioning of ecosystems by changing the appropriate locations for the development and establishment of the species. The Hancornia speciosa, popularly called Mangaba, is a plant species that has potential commercial value and contributes to rural economic activities in Brazil. The aim of this study was to evaluate the impact of global climate change on the potential geographic distribution, productivity, and value of production of H. speciosa in Brazil. We used MaxEnt to estimate the potential geographic distribution of the species in current and future (2050) climate scenarios. We obtained the productivity and value of production for 74 municipalities in Brazil. Moreover, to explain the variation the productivity and value of production, we constructed 15 models based on four variables: two ecological (ecological niche model and the presence of Unity of conservation) and two socio-economic (gross domestic product and human developed index). The models were selected using Akaike Information Criteria. Our results suggest that municipalities currently harvesting H. speciosa will have lower harvest rates in the future (mainly in northeastern Brazil). The best model to explain the productivity was ecological niche model; thus, municipalities with higher productivity are inserted in regions with higher environmental suitability (indicated by niche model). Thus, in the future, the municipalities harvesting H. speciosa will produce less because there will be less suitable habitat for H. speciosa, which in turn will affect the H. speciosa harvest and the local economy.

Na+/K+-ATPase resistance and cardenolide sequestration: basal adaptations to host plant toxins in the milkweed bugs (Hemiptera: Lygaeidae: Lygaeinae)

Despite sequestration of toxins being a common coevolutionary response to plant defence in phytophagous insects, the macroevolution of the traits involved is largely unaddressed. Using a phylogenetic approach comprising species from four continents, we analysed the ability to sequester toxic cardenolides in the hemipteran subfamily Lygaeinae, which is widely associated with cardenolide-producing Apocynaceae. In addition, we analysed cardenolide resistance of their Na(+)/K(+)-ATPases, the molecular target of cardenolides. Our data indicate that cardenolide sequestration and cardenolide-resistant Na(+)/K(+)-ATPase are basal adaptations in the Lygaeinae. In two species that shifted to non-apocynaceous hosts, the ability to sequester was secondarily reduced, yet Na(+)/K(+)-ATPase resistance was maintained. We suggest that both traits evolved together and represent major coevolutionary adaptations responsible for the evolutionary success of lygaeine bugs. Moreover, specialization on cardenolides was not an evolutionary dead end, but enabled this insect lineage to host shift to cardenolide-producing plants from distantly related families.

Evaluation of anti-inflammatory and mechanism of action of extract of Macrosiphonia longiflora (Desf.) Müll. Arg

ETHNOPHARMACOLOGICAL RELEVANCE

Macrosiphonia longiflora (Desf.) Müll. Arg (Apocynaceae), popularly known as 'velame' and 'velame branco', is a native subshrub that grows in the Brazilian Cerrado. This plant is widely used in traditional medicine in the form of decoction and infusion, particularly as anti-inflammatory, depurative, anti-rheumatic, antisyphilitic and antiulcer remedy. There is no available information in the literature that has addressed its pharmacological activity and phytochemical analysis.

AIM OF THE STUDY

This study aimed to evaluate the anti-inflammatory pharmacological profile of the hydroethanolic extract of Macrosiphonia longiflora, using in vivo and in vitro acute inflammation experimental models, as well as investigate the roles of cytokines and nitric oxide in its mechanism of action, and including phytochemical analysis constitution of its hydroethanolic extract.

MATERIALS AND METHODS

Hydroethanolic (70%) extract of Macrosiphonia longiflora (HEMl) was prepared by maceration. The preliminary phytochemical analysis was performed according to procedures described in the literature. Selected secondary metabolites detected were quantified by spectrophotometry and high performance liquid chromatography (HPLC). Its cytotoxic potential in Chinese hamster ovary (CHO-k1) epithelial cell lines was evaluated using Alamar Blue. in vivo anti-inflammatory activity was evaluated with carrageenan- and dextran-induced paw edemas, carrageenan-induced pleurisy in rats and lipopolysaccharide (LPS)-induced peritonitis in mice. The in vitro anti-inflammatory activity was evaluated using RAW 264.7 cells stimulated with LPS and interferon (INF)-γ. Effects of HEMl on the inflammatory cytokines (IL-1β, IL-10, IL-17, INF-γ and TNF-α) concentrations in the peritoneal lavage were evaluated using commercial ELISA kits, while the Griess method was employed to determine nitric oxide (NO) concentrations in the peritoneal lavage, as well as in the supernatants of RAW 264.7 cells.

RESULTS

Preliminary phytochemical analysis, revealed the presence of phenolics compounds, terpenoids, alkaloids and flavonoids. Spectrophotometric analysis revealed the presence of relatively high content of phenolics and flavonoids in HEMl. HPLC analysis confirmed the presence of the quantified compounds and demonstrated the presence of ellagic acid in the detected matrix of compounds. HEMl appeared to be non-cytotoxic. It effectively inhibited (p<0.05) paw edema induced by carrageenan and dextran. Furthermore, HEMl also significantly reduced exudates volume and leukocyte migration in the carrageenan-induced pleurisy and LPS-induced peritonitis, neutrophils counts in LPS-induced peritonitis. HEMl also acts by effectively inhibiting the following inflammatory cytokines: IL-1β and IL-10 levels in the peritoneal lavage, but had no effect on IL-17 level in the peritonitis model. In addition, HEMl had no effect on the levels of tumor necrosis factor alpha (TNF-α) present in the peritoneal lavage and cells supernatants. The concentration of NO, as assessed by measurement of nitrite (NO2(-)), showed that pretreatment with HEMl reduced NO significantly in the peritoneal lavage and in RAW 264.7 cells co-stimulated with LPS and INF-γ.

CONCLUSION

The results obtained in this study indicate that HEMl possesses very low cytotoxic potential. In addition, it demonstrated a potent anti-inflammatory activity in both the in vivo and in vitro models of acute inflammation. The anti-inflammatory effect is partly related to the inhibition of IL-1β, IL-10, and nitric oxide releases, but independent of TNF-α and IL-17 modulation. Phytochemical analysis revealed the predominant presence of the flavonoids (naringin, rutin, myricetin, morin, quercetin, (±)-naringenin, and luteolin) and phenols (ellagic acid), which are possibly involved in the anti-inflammatory effect of HEMl. The current study provided supportive evidence for the popular use of HEMl in the treatment of inflammatory conditions, and shed more light on the possible roles of the inflammatory cytokines in its mechanisms of action as anti-inflammatory agent.

The effect of management systems and ecosystem types on bark regeneration in Himatanthus drasticus (Apocynaceae): recommendations for sustainable harvesting

Bark and exudates are widely commercialized non-timber forest products. However, the ecological impacts of the harvesting of these products have seldom been studied. The aim of this study is to investigate the relationship of tree resilience to harvesting intensity in Himatanthus drasticus, a tree that is highly exploited in the Brazilian savanna (Cerrado) for its medicinal latex. Although the traded product is the latex, the traditional harvesting systems involve the removal of the bark of the trees to allow exploitation. A 3-year experiment was conducted in two different Cerrado ecosystems (open savanna and savanna woodland). Trees were debarked at four debarking intensities to simulate the effects of traditional management systems. Measurements of bark growth were taken every 6 months, and quantitative and qualitative indexes of bark regeneration were obtained. The mortality of the debarked trees was low and could not be related to the intensity of harvesting. No signs of attack by fungi or insects were recorded. Compared with other species exploited for bark, H. drasticus is very resilient to harvesting; however, bark regeneration is relatively slow. In both analyzed ecosystems, the regeneration indexes showed higher values in the controls than in the treatments, indicating that 3 years is not sufficient for total recovery of the rhytidome. Bark regeneration occurred primarily by sheet growth and was more rapid in open savanna than in savanna woodland. No differences in the rate of bark recovery were found among management treatments. Based on the results, sustainable harvesting guidelines are suggested for the species.

Cultivation practices and manufacturing processes to produce Hoodia gordonii extract for weight management products

Hoodia gordonii (Masson) Sweet ex Decne., is a succulent shrub, indigenous to the arid regions of southern Africa. Indigenous people have historically utilised certain species of Hoodia, including H. gordonii, as a source of food and water. Studies by the Council for Scientific and Industrial Research (CSIR, South Africa) identified that extracts of H. gordonii had appetite suppressant activity associated with specific steroid glycosides. A programme to develop weight management products based around this discovery was implemented in 1998. An agronomy programme was established which demonstrated that it was possible to cultivate this novel crop on a commercial scale (in excess of 70 ha). In parallel, a food grade manufacturing process was developed consisting of four main steps: harvesting of H. gordonii plant stems, comminution, drying under controlled conditions and extraction using food grade solvents. Appropriate Quality Control (QC) procedures were developed. The extraction process is capable of delivering a consistent composition despite natural variations in the composition of the dried H. gordonii. Specifications were developed for the resulting extract. The intended use of the standardised H. gordonii extract was as a functional food ingredient for weight management products. Other development studies on characterisation, toxicology and pharmacology are reported separately.

Development and reproduction of the foxglove aphid (Hemiptera: Aphididae) on invasive swallow-worts (Vincetoxicum spp.)

The foxglove aphid, Aulacorthum solani (Kaltenbach), recently was documented using the invasive species pale and black swallow-wort (Vincetoxicum rossicum (Kleopow) Barbar. and V. nigrum (L.) Moench, respectively) as host plants. Because these are new host plant records for this polyphagous species, we investigated foxglove aphid development and reproduction on pale and black swallow-wort relative to a known crop host, potato (Solanum tuberosum L.), at a 25:20°C thermophase and a photoperiod of 16:8 (L:D) h. Almost no such data have been previously reported for a noneconomic host plant. Larval development and survival, as well as adult reproductive development and fecundity, were similar between the two swallow-wort species and potato. Adult aphids lived significantly longer on pale swallow-wort than the other two host plants, but this extended longevity encompassed the postreproductive stage. Foxglove aphid population parameters were therefore similar among the three plant species as well as most previous reports on crop plants. Pale and black swallow-wort appear to be suitable secondary hosts for foxglove aphid; other factors possibly limit aphid abundance on these two plant species in the field.

Evaluation of host range and larval feeding impact of Chrysolina aurichalcea asclepiadis (Villa): considerations for biological control of Vincetoxicum in North America

A biological control program has been initiated against European swallow-worts Vincetoxicum nigrum (L.) Moench. and V. rossicum (Kleopow) Barbar., which are invasive in North America. A population of the leaf beetle Chrysolina aurichalcea asclepiadis (Villa) originating from the western Alps has been under evaluation as a part of this program. The preliminary host range of C. a. asclepiadis was determined among 37 potential host plants. In addition, a prerelease impact study was conducted to determine the effect of larval feeding on the performance of V. nigrum. Under no-choice conditions beetle larvae completed development on nine plant species within the genera Artemisia and Tanacetum (Asteraceae) and Asclepias and Vincetoxicum (Apocynaceae). The host range of adults is broader than larvae (13 plant species within five genera received sustained feeding). Three of the six nontarget species supporting larval development are native to North America, however in separate oviposition tests, female beetles failed to produce eggs when confined to these hosts. In multiple-choice tests, neither larvae nor adults preferred Vincetoxicum spp. to nontarget species. Larval damage by C. a. asclepiadis at densities at and above five larvae per plant substantially reduced growth, biomass, and delayed reproduction of V. nigrum. However, this population of C. a. asclepiadis is polyphagous and unsuitable for biological control of Vincetoxicum because of potential risk of attack to Asclepias tuberosa L. and native North American Asteraceae, particularly Artemisia.

Hoodia gordonii: an up-to-date review of a commercially important anti-obesity plant

Hoodia gordonii is a spiny succulent plant popularly consumed for its purported anti-obesity effect. Traditionally used by the Khoi-San of South Africa and Namibia as a hunger and thirst suppressant while on long hunting trips, the commercialisation of this plant has been highly controversial due to intellectual property rights and benefit sharing issues, as well as the fact that several prominent pharmaceutical companies involved in its development have withdrawn their interest. Quality control has been the main focus of scientific studies as the supply of H. gordonii plant material is limited due to its sparse geographical distribution, slow maturation rate, need for a permit to cultivate or export material as well as high public demand, contributing to adulteration of a large amount of products. Despite the isolation of numerous steroidal glycosides from H. gordonii, the main focus has been on the pregnane glycoside P57, considered to be the active ingredient and marker molecule to determine quality of raw material and products. Publications based on scientific studies of key aspects such as in vivo biopharmaceutics, the biological activity of all chemical constituents, clinical efficacy, and especially safety are insufficient or completely absent causing great concern as H. gordonii is one of the most widely consumed anti-obesity products of natural origin. This review offers an up-to-date overview of all the current available knowledge pertaining to H. gordonii achieved by systematic analysis of the available literature.

Age-size plasticity for reproduction in monocarpic plants

Empirical and theoretical investigations of monocarpy have usually addressed the question of minimum or threshold sizes for reproduction. However, the range of flowering sizes observed in many monocarpic species is extraordinarily large (well beyond what can be called a "threshold"), and the sizes of flowering and nonflowering plants may overlap greatly. We attempt to explain these reproductive patterns in terms of optimal reaction norms predicted by simple deterministic life history models. We assume that individuals differ in their growth trajectories due to the heterogeneous quality of microsites and ask how the optimal age and size at flowering varies with environmental variation in growth and for different assumptions about fecundity and mortality. Under two very different growth functions (one with no age- or size-related decline in growth rate and another with such a decline as size approaches an asymptote), the optimal reaction norms imply considerable plasticity for size at reproduction, particularly when poor growth is associated with higher mortality or lower asymptotic size. Deterministic models such as these may be more applicable to long-lived than to short-lived monocarps, because fitness potential should be less affected by stochastic variability in yearly growing condition in the former than in the latter. We consider the case of a tropical monocarpic and masting tree species, Cerberiopsis candelabra (Apocynaceae), and show that our model results can account for wide ranges of reproductive size and overlap in size of flowering and nonflowering plants, in accord with observation. We suggest that empirical attention to norms of reaction across growth environments will be a more profitable approach than investigation of size thresholds per se.

Do consecutive flower visits within a crown diminish fruit set in mass-flowering Hancornia speciosa (Apocynaceae)?

Hancornia speciosa is a self-incompatible, mass-flowering, sphingophilous fruit crop (mangaba) of northeast and central Brazil. The flowers have a precise pollination apparatus, which optimizes pollen transfer between flower and pollinator. While the pollination mechanism avoids self-pollination, mass-flowering promotes geitonogamy. During a flower visit, almost half of the exogenous pollen grains adhering to the proboscis are deposited on the stigma surface. A pollination experiment with a nylon thread simulating six consecutive flower visits within a crown revealed that only the first two flowers visited (positions 1 and 2) are highly likely to set fruit. Super-production of flowers, and consequently obligate low fruit set, seem to be part of the reproductive strategy of the obligate outcrossing plant, Hancornia speciosa.

Arbuscular mycorrhizal fungi increased early growth of two nontimber forest product species Dyera polyphylla and Aquilaria filaria under greenhouse conditions

Nontimber forest products (NTFPs) represent an important source of income to millions of people in tropical forest regions, but some NTFP species have decreased in number and become endangered due to overexploitation. There is increasing concern that the planting stocks of Dyera polyphylla and Aquilaria filaria are not sufficient to sustain the yield of NTFPs and promote forest conservation. The objective of this study was to determine the effect of two arbuscular mycorrhizal (AM) fungi, Glomus clarum and Gigaspora decipiens, on the early growth of two NTFP species, D. polyphylla and A. filaria, under greenhouse conditions. The seedlings of both species were inoculated with G. clarum or G. decipiens, or uninoculated (control) under greenhouse conditions. Percentage of AM colonization, plant growth, survival rate, and nitrogen (N) and phosphorus (P) concentrations were measured after 180 days of growth. The percentage of AM colonization of D. polyphylla and A. filaria ranged from 87 to 93% and from 22 to 39%, respectively. Colonization by G. clarum and G. decipiens increased plant height, diameter, and shoot and root dry weights. Shoot N and P concentrations of the seedlings were increased by AM colonization by as much as 70-153% and 135-360%, respectively. Survival rates were higher in the AM-colonized seedlings at 180 days after transplantation than in the control seedlings. The results suggest that AM fungi can accelerate the establishment of the planting stocks of D. polyphylla and A. filaria, thereby promoting their conservation ecologically and sustaining the production of these NTFPs economically.

Long range dispersal and spatial pattern formation in biological invasions

In this paper we explore the consequences of long distance dispersal in biological invasion processes through simulations using a recently developed cellular automaton model. We show that long distance dispersal generate characteristic spatial patterns with several stationary scale-invariant properties. In particular, the patterns display a main patch around the focus of spread, with a fractal border structure whose fractal dimension contains information about the main statistical properties of the dispersal mechanism. Our results are in agreement with field data of spread of invaders with long distance dispersal mechanisms.

Leaf life span plasticity in tropical seedlings grown under contrasting light regimes

BACKGROUND AND AIMS

The phenotypic plasticity of leaf life span in response to low resource conditions has a potentially large impact on the plant carbon budget, notably in evergreen species not subject to seasonal leaf shedding, but has rarely been well documented. This study evaluates the plasticity of leaf longevity, in terms of its quantitative importance to the plant carbon balance under limiting light.

METHODS

Seedlings of four tropical tree species with contrasting light requirements (Alstonia scholaris, Hevea brasiliensis, Durio zibethinus and Lansium domesticum) were grown under three light regimes (full sunlight, 45 % sunlight and 12 % sunlight). Their leaf dynamics were monitored over 18 months.

RESULTS

All species showed a considerable level of plasticity with regard to leaf life span: over the range of light levels explored, the ratio of the range to the mean value of life span varied from 29 %, for the least plastic species, to 84 %, for the most. The common trend was for leaf life span to increase with decreasing light intensity. The plasticity apparent in leaf life span was similar in magnitude to the plasticity observed in specific leaf area and photosynthetic rate, implying that it has a significant impact on carbon gain efficiency when plants acclimate to different light regimes. In all species, median survival time was negatively correlated with leaf photosynthetic capacity (or its proxy, the nitrogen content per unit area) and leaf emergence rate.

CONCLUSIONS

Longer leaf life spans under low light are likely to be a consequence of slower ageing as a result of a slower photosynthetic metabolism.

Variation in the mating system of Vincetoxicum hirundinaria (Asclepiadaceae) in peripherial island populations

BACKGROUND AND AIMS

Self-fertility may be selected for in small and isolated plant populations of normally outcrossing species. In addition, adaptations for self-fertility are likely to arise in island populations and in populations that are located at the border of the species range. The mating system of Vincetoxicum hirundinaria (Asclepiadaceae) is examined in island populations that are located at the northern border of the species range.

METHODS

Pollination experiments were conducted under glasshouse conditions with plants from four populations.

KEY RESULTS

The frequencies of self-fertile individuals were relatively high and did not differ among populations. Cross-pollination resulted in higher fruit set than self-pollination. However, fruit-set from self-pollination and cross-pollination did not differ in the self-fertile individuals. Interestingly, the proportion of aborted fruits was on average higher following cross-pollination than following self-pollination. No differences were observed in seed number or seed mass between self- and cross-pollinated fruits. Pollen tube growth following self- and cross-pollinations was indistinguishable.

CONCLUSIONS

The results of this study revealed that V. hirundinaria possess a mixed-mating system in the studied island populations. Evidence was also provided for a late-acting self-incompatibility system commonly observed in Asclepiadaceae. No clear signs of inbreeding depression were observed in the early stages of development.

Transcriptional and post-translational regulation of S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase (SAMT) during Stephanotis floribunda flower development

Methyl salicylate (MeSA) and a number of other volatiles are primarily emitted in the evening/night by Stephanotis floribunda leading to attraction of night active pollinators. A second minor emission peak for MeSA occurs in the morning/day. To understand these emission patterns, we have studied in detail the temporal regulation of the last step of the biosynthetic pathway of MeSA, the convertion of salicylic acid (SA) to MeSA catalysed by S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase (SAMT). We observed that in young flowers a maximum in SAMT activity occurs in the night, and that in flowers which were open longer than 4 days, two SAMT activity maxima occurred per day. These maxima correlated well with dawn and dusk and the previously detected MeSA emission peaks. The SAMT mRNA levels, however, have a broad maximum during the dark phase, while the SAMT protein levels continuously increase during floral development without showing daily rhythms. Furthermore, under continuous illumination (LL) the SAMT mRNA levels and activity patterns oscillate, suggesting the involvement of a circadian clock in the regulation network. Taken together, this analysis clearly demonstrates that regulation of MeSA emission occurs both at the transcriptional and post-translational levels, indicating that control at more than one level is necessary to guarantee the precise timing of volatile emission in flowers of S. floribunda.

Mechanical, chemical and X-ray analysis of wood in the two tropical lianas Bauhinia guianensis and Condylocarpon guianense: variations during ontogeny

Mechanical and chemical properties as well as microfibril angles of wood tissues from different ontogenetic stages are determined for the neotropical lianas Bauhinia guianensis and Condylocarpon guianense. The mechanical properties include the elastic moduli under bending and under dynamic torsion. The chemical analyses cover (i) the content of cellulose, lignin and hemicelluloses fractions, (ii) the monomeric composition of the uncondensed lignin, and (iii) the composition of the hemicelluloses with respect to neutral monosaccharides. By comparing the wood properties of these lianas with the corresponding properties of wood from self-supporting deciduous trees, common characteristics and differences are revealed. Additionally, the changes in the lignin and polysaccharides fractions as well as the variations in microfibril orientation that occur during ontogeny of the two liana species are discussed with regard to their implications for the mechanical properties of wood.

Inhibition of growth of microcultured Hancornia speciosa shoots by 3beta-hydroxylated gibberellins and one of their C-3 deoxy precursors

Gibberellins (GAs) A(1), A(3), A(4) and A(7), all 3beta-hydroxylated, growth-active GAs, significantly inhibited shoot elongation and the formation of nodes in in vitro-grown Hancornia speciosa, as did GA(20), a 3-deoxy precursor of GA(1). Ancymidol, an early-stage inhibitor of GA biosynthesis, significantly retarded shoot elongation without affecting the formation of nodes. Co-application of ancymidol and GA(1 )did not overcome the ancymidol-induced growth retardation. Trinexapac-ethyl, which can inhibit 3beta-hydroxylation (GA activation) and 2beta-hydroxylation (GA inactivation), gave no significant response on either shoot elongation or node formation, while two isomers of 16,17-dihydro GA(5), also inhibitors of GA 3beta-hydroxylation, significantly inhibited both shoot growth and the formation of nodes. These unusual results may indicate a unique metabolism for GAs in microcultured shoots of H. speciosa.

Immunolocalization of beta-D-glucans, pectins, and arabinogalactan-proteins during intrusive growth and elongation of nonarticulated laticifers in Asclepias speciosa Torr

Nonarticulated laticifers are latex-containing cells that elongate indefinitely and grow intrusively between the walls of meristematic cells. To identify biochemical mechanisms involved in the growth of nonarticulated laticifers, we have analyzed the distribution of various polysaccharides and proteoglycans in walls of meristematic cells in contact with laticifers, nonadjacent to laticifers, and in laticifer walls. In the shoot apex of Asclepias speciosa, the levels of callose and a (1-->4)-beta-galactan epitope are lower in meristematic walls in contact with laticifers than in nonadjacent walls. In contrast, we did not detect a decline in xyloglucan, homogalacturonan, and arabinogalactan-protein epitopes upon contact of meristematic cells with laticifers. Laticifer elongation is also associated with the development of a homogalacturonan-rich middle lamella between laticifers and their neighboring cells. Furthermore, laticifers lay down walls that differ from those of their surrounding cells. This is particularly evident for epitopes in rhamnogalacturonan I. A (1-->5)-alpha-arabinan epitope in this pectin is more abundant in laticifers than meristematic cells, while the opposite is observed for a (1-->4)-beta-galactan epitope. Also, different cell wall components exhibit distinct distribution patterns within laticifer walls. The (1-->5)-alpha-arabinan epitope is distributed throughout the laticifer walls while certain homogalacturonan and arabinogalactan-protein epitopes are preferentially located in particular regions of laticifer walls. Taken together, our results indicate that laticifer penetration causes changes in the walls of meristematic cells and that there are differences in wall composition within laticifer walls and between laticifers and their surrounding cells.

Genetic transformation and hairy root induction in Holostemma ada-kodien K. Schum--a vulnerable medicinal plant

Hairy roots were induced from shoot buds and seedling hypocotyls of Holostemma by infection with agropine type Agrobacterium rhizogenes strains. Type of explant, Agrobacterium rhizogenes strain used for infection, co-culture time and photoperiod influenced the transformation frequencies. Hairy roots were induced from seedling hypocotyls and shoot bud explants upon infection with agropine type Agrobacterium rhizogenes strains. The hairy roots were thin, whitish in colour and showed negatively geotropic growth. The transformed nature of hairy roots was confirmed by opine analysis.