Tamarind genus chemical composition and biological activities

Tamarindus indica L., the sole species in the genus Tamarind, which is a member of the subfamily Caesalpiniaceae in the family Leguminosae (Fabaceae), is extensively dispersed in many tropical and subtropical regions. This plant's Arabic name, Tamr Al-Hindi, is the basis for its English name, Tamarind. In traditional medicine, this genus has played a major role since the time of the ancient Egyptians. Folkloric medicine has traditionally used Tamarind to treat a variety of conditions, including diabetes mellitus, fever, malaria, ulcers, diarrhoea, dysentery and wounds. The primary bioactive components of this species, which have a variety of biological functions, have been identified as flavonoids, phenolic contents, sterols, triterpenes, fatty acids, sugars and other substances. Genus Tamarind has been shown to have anti-inflammatory, analgesic, anti-pyretic, antibacterial, hypolipidemic, anti-diabetic, hepatoprotective, anti-ulcerogenic and antioxidant properties. This article provides an overview of the identified chemicals from T. indica together with their stated biological activities.

Competitive CatSper Activators of Progesterone from Rhynchosia volubilis

The root Rhynchosia volubilis was widely used for contraception in folk medicine, although its molecular mechanism on antifertility has not yet been revealed. In human sperm, it was reported that the cation channel of sperm, an indispensable cation channel for the fertilization process, could be regulated by various steroid-like compounds in plants. Interestingly, these nonphysiological ligands would also disturb the activation of the cation channel of sperm induced by progesterone. Therefore, this study aimed to explore whether the compounds in R. volubilis affect the physiological regulation of the cation channel of sperm. The bioguided isolation of the whole herb of R. volubilis has resulted in the novel discovery of five new prenylated isoflavonoids, rhynchones A - E (1:  - 5: ), a new natural product, 5'-O-methylphaseolinisoflavan (6: ) (¹H and ¹³C NMR data, Supporting Information), together with twelve known compounds (7:  - 18: ). Their structures were established by extensive spectroscopic analyses and drawing a comparison with literature data, while their absolute configurations were determined by electronic circular dichroism calculations. The experiments of intracellular Ca²⁺ signals and patch clamping recordings showed that rhynchone A (1: ) significantly reduced cation channel of sperm activation by competing with progesterone. In conclusion, our findings indicat that rhynchone A might act as a contraceptive compound by impairing the activation of the cation channel of sperm and thus prevent fertilization.

Chemical constituents from Maackia amurensis and their anti-inflammatory and antioxidant activities

A new flavonoid named (2S)-7,4'-dimethoxyl-6-(2″,3″-epoxy-3″-methylbutyl)flavanone (1), along with five known compounds (2-6), were isolated from the EtOAc-soluble extract of the stem bark of Maackia amurensis. Their structures were elucidated on the basis of spectroscopic methods. All compounds were evaluated for anti-inflammatory and antioxidant activities in vitro. Among them, compound 5 showed the highest inhibitory activity on NO production in RAW264.7 cells stimulated by LPS with IC₅₀ value of 59.0 ± 1.5 µM. Meanwhile, compounds 1-6 exhibited varying antioxidant activities through DPPH, ABTS free radical-scavenging and FRAP assays.

GC-MS Based Identification of the Volatile Components of Six Astragalus Species from Uzbekistan and Their Biological Activity

The compositions of volatile components in the aerial parts of six Astragalus species, namely A. campylotrichus (Aca), A. chiwensis (Ach), A. lehmannianus (Ale), A. macronyx (Ama), A. mucidus (Amu) and A. sieversianus (Asi), were investigated using gas chromatograph-mass spectrometry (GC-MS) analysis. Ninety-seven metabolites were identified, accounting for 73.28, 87.03, 74.38, 87.93, 85.83, and 91.39% of Aca, Ach, Ale, Ama, Amu and Asi whole oils, respectively. Sylvestrene was the most predominant component in Asi, Amu and Ama, with highest concentration in Asi (64.64%). In addition, (E)-2-hexenal was present in a high percentage in both Ale and Ach (9.97 and 10.1%, respectively). GC-MS based metabolites were subjected to principal component analysis (PCA) and hierarchal cluster analysis (HCA) to explore the correlations between the six species. The PCA score plot displayed clear differentiation of all Astragalus species and a high correlation between the Amu and Ama species. The antioxidant activity was evaluated in vitro using various assays, phosphomolybdenum (PM), 2,2 diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-azino bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), ferric reducing power (FRAP) and ferrous ion chelation (FIC) assays. In addition, the potential for the volatile samples to inhibit both acetyl/butyrylcholinesterases (AChE, BChE), α- amylase, α-glucosidase and tyrosinase was assessed. Most of the species showed considerable antioxidant potential in the performed assays. In the DPPH assay, Ama exhibited the maximum activity (24.12 ± 2.24 mg TE/g sample), and the volatiles from Amu exhibited the highest activity (91.54 mgTE/g oil) in the ABTS radical scavenging assay. The effect was more evident in both CUPRAC and FRAP assays, where both Ale and Ama showed the strongest activity in comparison with the other tested species (84.06, 80.28 mgTE/g oil for CUPRAC and 49.47, 49.02 mgTE/g oil for FRAP, respectively). Asi demonstrated the strongest AChE (4.55 mg GALAE/g oil) and BChE (3.61 mg GALAE/g oil) inhibitory effect. Furthermore, the best tyrosinase inhibitory potential was observed for Ale (138.42 mg KAE/g). Accordingly, Astragalus species can be utilized as promising natural sources for many medicinally important components that could be tested as drug candidates for treating illnesses such as Alzheimer's disease, diabetes mellitus and oxidative stress-related diseases.

A new isoflavone glycoside from Abrus cantoniensis

A new isoflavone glycoside named as 8-O-methylrelusin-7-O-β-D-apifuranosyl-(1→2)-β-D-glucopyranoside (1), together with two known compounds, 8-O-methylrelusin-7-O-β-D-glucopyranoside (2) and isobiflorin (3), were isolated from Abrus cantoniensis. The structure of the new compound was elucidated on the basis of spectroscopic methods including extensive 1D NMR, 2D NMR, and HRESIMS. This is the first report of isoflavone from Abrus cantoniensis. Moreover, all isolated compounds were evaluated for their cytotoxicity against SMMC-7721 and MHCC97-H cell lines.[Formula: see text].

Leishmanicidal phenolic compounds derived from Dalbergia cultrata

Leishmaniasis is a protozoan tropical infection that is estimated to be more than 0.3 million new cases occur annually worldwide. A novel phenolic compound, cultratin A (1), was isolated as a leishmanicidal constituent from the timber of Dalbergia cultrata, along with three known neoflavanoids (2, 3, 4), two benzofurans (5, 6), and two phenolic compounds (7, 8). Their structures were determined using spectral methods. Among them, a new compound (1) and 4-(S)-methoxydalbergione (2) showed effective leishmanicidal activities (IC₅₀: 2.0 and 2.6 μM, respectively), while compound 8 showed moderate activity (IC₅₀: 11 μM). The cytotoxicity of compounds 1 and 2 was also weaker than that of the other compounds.

(Papilionoideae, Leguminosae)

Stylosanthes (Papilionoideae, Leguminosae) is a predominantly Neotropical genus with ~48 species that include worldwide important forage species. This study presents the chromosome number and morphology of eight species of the genus Stylosanthes (S. acuminata, S. gracilis, S. grandifolia, S. guianensis, S. hippocampoides, S. pilosa, S. macrocephala, and S. ruellioides). In addition, staining with CMA and DAPI, in situ hybridization with 5S and 35S rDNA probes, and estimation of DNA content were performed. The interpretation of Stylosanthes chromosome diversification was anchored by a comparison with the sister genus Arachis and a dated molecular phylogeny based on nuclear and plastid loci. Stylosanthes species showed 2n = 20, with low cytomolecular diversification regarding 5S rDNA, 35S rDNA, and genome size. Arachis has a more ancient diversification (~7 Mya in the Pliocene) than the relatively recent Stylosanthes (~2 Mya in the Pleistocene), and it seems more diverse than its sister lineage. Our data support the idea that the cytomolecular stability of Stylosanthes in relation to Arachis could be a result of its recent origin. The recent diversification of Stylosanthes could also be related to the low morphological differentiation among species, and to the recurrent formation of allopolyploid complexes.

Completed plastome sequence of Sophora moorcroftiana, an endemic shrub to the Qinghai-Tibet Plateau, China

Sophora moorcroftiana, an endemic Fabaceae species occurred in the Qinghai-Tibet plateau, China, has important economic value in local. Its completed plastome sequence is 148,930 bp in size, and comprises a pair of inverted repeat (IR) regions of 23,787 bp each, a large single-copy region of 83,342 bp and a small single-copy region of 18,014 bp. The GC content of the plastome was 30.2%. A total of 124 genes were identified, comprising 80 protein-coding genes, 36 tRNA genes and eight rRNA genes. There are 94 unique genes, with 15 genes duplicated in the IR regions. Phylogenetic tree shows that plastome of S. moorcroftiana is most related to that of S. alopecuroides. This plastome would be helpful for the study of molecular mechanism of photosynthesis, sustainable conservation, genetic improvement of S. moorcroftiana.

Symbiotic dinitrogen fixation is seasonal and strongly regulated in water-limited environments

Plants, especially perennials, growing in drylands and seasonally dry ecosystems are uniquely adapted to dry conditions. Legume shrubs and trees, capable of symbiotic dinitrogen (N₂ ) fixation, often dominate in drylands. However, the strategies that allow symbiotic fixation in these ecosystems, and their influence on the nitrogen cycle, are largely unresolved. We evaluated the climatic, biogeochemical and ontogenetic factors influencing nitrogen fixation in an abundant Mediterranean legume shrub, Calicotome villosa. We measured nodulation, fixation rate, nitrogen allocation and soil biogeochemistry in three field sites over a full year. A controlled experiment evaluated differences in plant regulation of fixation as a function of soil nutrient availability and seedling and adult developmental stages. We found a strong seasonal pattern, shifting between high fixation rates during the rainy season at flowering and seed-set times to almost none in the rainless season. Under controlled conditions, plants downregulated fixation in response to soil nitrogen availability, but this response was stronger in seedlings than in adult shrubs. Finally, we did not find elevated soil nitrogen under N₂ -fixing shrubs. We conclude that seasonal nitrogen fixation, regulation of fixation, and nitrogen conservation are key adaptations influencing the dominance of dryland legumes in the community, with broader consequences on the ecosystem nitrogen cycle.

[Structure Analysis of Arbuscular Mycorrhizal in Roots from Different Shrubs in Karst Regions]

To explore if there are species-preferential characteristics of arbuscular mycorrhizal (AM) and host plants in karst regions, 13 shrub plants (including leguminosae and non-leguminosae) were selected to study the AM community structure of root samples. The soil nutrients in rhizosphere soils significantly differ among shrubs; they are higher in leguminosae than in non-leguminosae. Cluster analysis shows that all 13 shrubs can be infected by AM. Significant differences of the AM community structure were observed among root samples from different shrubs, especially leguminosae and non-leguminosae. Redundancy analysis shows that soil Olsen-P, pH, and total nitrogen significantly influence the AM community structure of plant roots, although the factors affecting this fungus in leguminosae and non-leguminosae differ. These results indicate species-preferential characteristics of AM and host plants in karst regions, especially of the plant function group compared with plant species, suggesting that these characteristics should be taken into account when AM fungi are used for vegetation restoration in karst regions.

Which Plants Used in Ethnomedicine Are Characterized? Phylogenetic Patterns in Traditional Use Related to Research Effort

Plants are important resources in healthcare and for producing pharmaceutical drugs. Pharmacological and phytochemical characterization contributes to both the safe use of herbal medicines and the identification of leads for drug development. However, there is no recent assessment of the proportion of plants used in ethnomedicine that are characterized in this way. Further, although it is increasingly apparent that plants used in ethnomedicine belong to preferred phylogenetic lineages, it is not known how this relates to the focusing of research effort. Here we identify species and lineages rich in ethnomedicinal use and develop methods to describe how well they are known pharmacologically and/or phytochemically. We find 50% of plant species of the family Leguminosae used in ethnomedicine in Brazil, a geographical area where plants are an important part of healthcare, have been the focus of either phytochemical screening or testing for biological activity. Plant species which have more use reports are studied significantly more often (p < 0.05). Considering the taxonomic distribution of use, 70% of genera that include species with ethnomedicinal use have been studied, compared to 19% of genera with no reported use. Using a novel phylogenetic framework, we show that lineages with significantly greater numbers of ethnomedicinal species are phylogenetically over-dispersed within the family, highlighting the diversity of species used. "Hotnode clades" contain 16% of species but 46% of ethnomedicinally-used species. The ethnomedicinal species in hotnode clades have more use reports per species (p < 0.05), suggesting they are more frequently used. They are also more likely to be characterized pharmacologically and/or phytochemically. Research focus has followed traditional use by these measures, at least for these Brazilian plants, yet ethnomedicinal species yielding candidate drugs, raising public health concerns and more intensively studied lie outside of the hotnode clades.

Soluble Epoxide Hydrolase Inhibitory Activity of Components Isolated from Apios americana Medik

A new compound 1, 5-methoxy-2,5,7,4′-tetrahydroxy-coumaronochromone, along with seven known compounds (2–8), were isolated from Apios americana using open column chromatography. Their structures were established based on an analysis of 1D and 2D NMR, and MS spectra. Among these, two compounds 1 and 2 showed inhibitory activity on soluble epoxide hydrolase (sEH) at a concentration below 50 μM. The respective competitive (1) and mixed (2) inhibitors were revealed to have K_i values of 21.0 ± 0.8 and 14.5 ± 1.5 μM, based on the Dixon plot. The potential inhibitor (2) was visually presented in a predicted binding pose in the receptor by molecular docking. Additionally, molecular dynamics were performed for a detailed understanding of their complex by Gromacs 4.6.5 package.

Cytotoxic constituents from the seeds of Vietnamese Caesalpinia sappan

CONTEXT

Caesalpinia sappan Linn. (Leguminosae) has been used in folk medicines for the treatment of many diseases. The heartwood of this plant contains various phenolic components with interesting biological applications; however, the chemical and biological potentials of the seed of this plant have not been fully explored.

OBJECTIVE

This study identified the cytotoxic activity of compounds from the seeds of C. sappan.

MATERIALS AND METHODS

The methanol extract of the seed of C. sappan was suspended in H2O and then partitioned with CH2Cl2, EtOAc, and n-BuOH, successively. Diterpenoid compounds were isolated from the CH2Cl2-soluble fraction by silica gel column chromatography methods using organic solvents. The compound structures were determined by detailed analysis of NMR and MS spectral data. Cytotoxic activity was measured using a modified MTT assay against HL-60, HeLa, MCF-7, and LLC cancer cells. The activation of caspase-3 enzyme and western blotting assay were performed to confirm inhibitory mechanism of active compound.

RESULTS

Five cassane-type diterpenoids were isolated and identified as phanginin I (1), phaginin A (2), phanginin D (3), phanginin H (4), and phanginin J (5). Compounds 1-4 showed effective inhibition against HL-60 cells with the IC50 values of 16.4 ± 1.5, 19.2 ± 2.0, 11.7 ± 1.6, and 22.5 ± 5.1 μM. Compounds 1-3 exhibited cytotoxic activity against HeLa cells with the IC50 values of 28.1 ± 3.6, 37.2 ± 3.4, and 22.7 ± 2.8 μM. Treatment of HL-60 cell lines with various concentrations of 3 (0-30 μM) resulted in the growth inhibition and induction of apoptosis.

CONCLUSION

These findings demonstrate that compound 3 (phanginin D) is one of the main active components of the seed of C. sappan activating caspases-3 which contribute to apoptotic cell death.

Three new phenolic compounds from Dalbergia odorifera

Three new phenolic compounds (1-3) were isolated from the heartwood of Dalbergia odorifera T. Chen. (Leguminosae). Their structures were established based on spectroscopic methods including 1D and 2D NMR (HSQC, COSY, HMBC and ROESY). Compound 2 exhibited cytotoxicity against BEL-7402 tumor cell lines.

Morphologies and elemental compositions of calcium crystals in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosoideae)

BACKGROUND AND AIMS

Formation of calcium oxalate crystals is common in the plant kingdom, but biogenic formation of calcium sulfate crystals in plants is rare. We investigated the morphologies and elemental compositions of crystals found in phyllodes and branchlets of Acacia robeorum, a desert shrub of north-western Australia.

METHODS

Morphologies of crystals in phyllodes and branchlets of A. robeorum were studied using scanning electron microscopy (SEM), and elemental compositions of the crystals were identified by energy-dispersive X-ray spectroscopy. Distributional patterns of the crystals were studied using optical microscopy together with SEM.

KEY RESULTS

According to the elemental compositions, the crystals were classified into three groups: (1) calcium oxalate; (2) calcium sulfate, which is a possible mixture of calcium sulfate and calcium oxalate with calcium sulfate being the major component; and (3) calcium sulfate · magnesium oxalate, presumably mixtures of calcium sulfate, calcium oxalate, magnesium oxalate and silica. The crystals were of various morphologies, including prisms, raphides, styloids, druses, crystal sand, spheres and clusters. Both calcium oxalate and calcium sulfate crystals were observed in almost all tissues, including mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex; calcium sulfate · magnesium oxalate crystals were only found in mesophyll and parenchyma cells in phyllodes.

CONCLUSIONS

The formation of most crystals was biologically induced, as confirmed by studying the crystals formed in the phyllodes from seedlings grown in a glasshouse. The crystals may have functions in removing excess calcium, magnesium and sulfur, protecting the plants against herbivory, and detoxifying aluminium and heavy metals.

Iron and zinc retention in common beans (Phaseolus vulgaris L.) after home cooking

Background

According to the World Health Organization (WHO), iron, iodine, and Vitamin A deficiencies are the most common forms of malnutrition, leading to severe public health consequences. The importance of iron and zinc in human nutrition and the number of children found to be deficient in these nutrients make further studies on retention in cooked grains and cooked bean broth important.

Objectives

This work aimed to evaluate iron and zinc retention in six common bean (Phaseolus vulgaris L.) cultivars under the following conditions: raw beans, regular pot cooking, pressure cooking, with and without previous water soaking, and broth.

Design

Determination of iron and zinc content in the raw, cooked bean grains and broth samples was carried out by Inductively Coupled Plasma (ICP) Optical Emission Spectrometry (Spectro Analytical Instrument – Spectroflame P). All experiments and analyses were carried out in triplicate.

Results

Overall, regardless of the cooking method, with or without previous water soaking, the highest zinc concentration was found in the cooked bean grains. However, pressure cooking and previous water soaking diminished iron retention in the cooked grains, while increasing it in the bean broth.

Conclusion

The common bean was confirmed to be an excellent source of iron and zinc for human consumption, and it was suggested that beans should be consumed in a combined form, i.e. grain with bean broth.

Kaempferia parviflora, a plant used in traditional medicine to enhance sexual performance contains large amounts of low affinity PDE5 inhibitors

AIM OF THE STUDY

A number of medicinal plants are used in traditional medicine to treat erectile dysfunction. Since cyclic nucleotide PDEs inhibitors underlie several current treatments for this condition, we sought to show whether these plants might contain substantial amounts of PDE5 inhibitors.

MATERIALS AND METHODS

Forty one plant extracts and eight 7-methoxyflavones from Kaempferia parviflora Wall. ex Baker were screened for PDE5 and PDE6 inhibitory activities using the two-step radioactive assay. The PDE5 and PDE6 were prepared from mice lung and chicken retinas, respectively. All plant extracts were tested at 50 μg/ml whereas the pure compounds were tested at 10 μM.

RESULTS

From forty one plant extracts tested, four showed the PDE5 inhibitory effect. The chemical constituents isolated from rhizomes of Kaempferia parviflora were further investigated on inhibitory activity against PDE5 and PDE6. The results showed that 7-methoxyflavones from this plant showed inhibition toward both enzymes. The most potent PDE5 inhibitor was 5,7-dimethoxyflavone (IC(50) = 10.64 ± 2.09 μM, selectivity on PDE5 over PDE6 = 3.71). Structure activity relationship showed that the methoxyl group at C-5 position of 7-methoxyflavones was necessary for PDE5 inhibition.

CONCLUSIONS

Kaempferia parviflora rhizome extract and its 7-methoxyflavone constituents had moderate inhibitory activity against PDE5. This finding provides an explanation for enhancing sexual performance in the traditional use of Kaempferia parviflora. Moreover, 5,7-dimethoxyflavones should make a useful lead compound to further develop clinically efficacious PDE5 inhibitors.

Molecular phylogeny of the subgenus Ceratotropis (genus Vigna, Leguminosae) reveals three eco-geographical groups and Late Pliocene-Pleistocene diversification: evidence from four plastid DNA region sequences

BACKGROUND AND AIMS

The subgenus Ceratotropis in the genus Vigna is widely distributed from the Himalayan highlands to South, Southeast and East Asia. However, the interspecific and geographical relationships of its members are poorly understood. This study investigates the phylogeny and biogeography of the subgenus Ceratotropis using chloroplast DNA sequence data.

METHODS

Sequence data from four intergenic spacer regions (petA-psbJ, psbD-trnT, trnT-trnE and trnT-trnL) of chloroplast DNA, alone and in combination, were analysed using Bayesian and parsimony methods. Divergence times for major clades were estimated with penalized likelihood. Character evolution was examined by means of parsimony optimization and MacClade.

KEY RESULTS

Parsimony and Bayesian phylogenetic analyses on the combined data demonstrated well-resolved species relationships in which 18 Vigna species were divided into two major geographical clades: the East Asia-Southeast Asian clade and the Indian subcontinent clade. Within these two clades, three well-supported eco-geographical groups, temperate and subtropical (the East Asia-Southeast Asian clade) and tropical (the Indian subcontinent clade), are recognized. The temperate group consists of V. minima, V. nepalensis and V. angularis. The subtropical group comprises the V. nakashimae-V. riukiuensis-V. minima subgroup and the V. hirtella-V. exilis-V. umbellata subgroup. The tropical group contains two subgroups: the V. trinervia-V. reflexo-pilosa-V. trilobata subgroup and the V. mungo-V. grandiflora subgroup. An evolutionary rate analysis estimated the divergence time between the East Asia-Southeast Asia clade and the Indian subcontinent clade as 3·62 ± 0·3 million years, and that between the temperate and subtropical groups as 2·0 ± 0·2 million years.

CONCLUSIONS

The findings provide an improved understanding of the interspecific relationships, and ecological and geographical phylogenetic structure of the subgenus Ceratotropis. The quaternary diversification of the subgenus Ceratotropis implicates its geographical dispersal in the south-eastern part of Asia involving adaptation to climatic condition after the collision of the Indian subcontinent with the Asian plate. The phylogenetic results indicate that the epigeal germination is plesiomorphic, and the germination type evolved independently multiple times in this subgenus, implying its limited taxonomic utility.

The known immunologically active components of Astragalus account for only a small proportion of the immunological adjuvant activity when combined with conjugate vaccines

The 95 % ethanol extract of Astragalus has been demonstrated to have potent activity as an immunological adjuvant when administered with vaccines of various types. We endeavor here to identify the components of this extract that are responsible for this adjuvant activity. Mice were immunized with KLH conjugated to cancer carbohydrate antigens globo H and GD3 and cancer peptide antigen MUC1 combined with different Astragalus fractions or with commercially available Astragalus saponins and flavonoids. The antibody responses against cancer antigens and KLH were quantitated in ELISA assays, and toxicity was calculated by weight loss. Astragalosides II and IV were the most active components, but the toxicity of these two differed dramatically. Astragaloside II was the most toxic Astragalus component with 5-10 % weight loss at a dose of 500 µg while astragaloside IV showed no weight loss at all at this dose, suggesting that astragaloside IV might be utilized as an immunological adjuvant in future studies. Several flavonoids also had significant adjuvant activity. However, when the activities of these known immunologically active components of Astragalus (and of endotoxin) are calculated based on the extent of their presence in the 95 % ethanol extract, they provide only a small proportion of the immunological activity. This raises the possibility that additional uniquely active components of Astragalus may contribute to adjuvant activity, or that the adjuvant activity of Astragalus is greater than the activity of the sum of its parts.

Morphological evolution in the variable resin-producing Detarieae (Fabaceae): do morphological characters retain a phylogenetic signal?

BACKGROUND AND AIMS

Previous molecular phylogenetic studies disagree with the informal generic-level taxonomic groups based on morphology. In this study morphological characters in the caesalpinioid clade Detarieae are evaluated within a phylogenetic framework as a means of better understanding phylogenetic relationships and morphological evolution.

METHODS

Morphological characters were observed and scored for representative species of Detarieae focusing on the resin-producing genera. Phylogenetic analyses were carried out with morphological characters alone and then combined with DNA sequences.

KEY RESULTS

Despite a high level of homoplasy, morphological data support several clades corresponding to those recovered in molecular phylogenetic analyses. The more strongly supported clades are each defined by at least one morphological synapomorphy. Several characters (e.g. apetaly) previously used to define informal generic groups evolved several times independently, leading to the differences observed with the molecular phylogenetic analyses. Although floral evolution is complex in Detarieae some patterns are recovered.

CONCLUSIONS

New informal taxonomic groupings are proposed based on the present findings. Floral evolution in the diverse Detarieae clade is characterized by a repeated tendency toward zygomorphy through the reduction of lateral petals and toward complete loss of petals.

Crystallization and preliminary crystallographic characterization of glutamine synthetase from Medicago truncatula

The condensation of ammonium and glutamate into glutamine catalyzed by glutamine synthetase (GS) is a fundamental step in nitrogen metabolism in all kingdoms of life. In plants, this is preceded by the reduction of inorganic nitrogen to an ammonium ion and therefore effectively articulates nitrogen fixation and metabolism. Although the three-dimensional structure of the dodecameric bacterial GS was determined quite some time ago, the quaternary architecture of the plant enzyme has long been assumed to be octameric, mostly on the basis of low-resolution electron-microscopy studies. Recently, the crystallographic structure of a monocotyledonous plant GS was reported that revealed a homodecameric organization. In order to unambiguously establish the quaternary architecture of GS from dicotyledonous plants, GS1a from the model legume Medicago truncatula was overexpressed, purified and crystallized. The collection of synchrotron diffraction data to 2.35 A resolution allowed the determination of the three-dimensional structure of this enzyme by molecular replacement.

Floral morphology and development in Quillajaceae and Surianaceae (Fabales), the species-poor relatives of Leguminosae and Polygalaceae

BACKGROUND AND AIMS

Molecular phylogenies have suggested a new circumscription for Fabales to include Leguminosae, Quillajaceae, Surianaceae and Polygalaceae. However, recent attempts to reconstruct the interfamilial relationships of the order have resulted in several alternative hypotheses, including a sister relationship between Quillajaceae and Surianaceae, the two species-poor families of Fabales. Here, floral morphology and ontogeny of these two families are investigated to explore evidence of a potential relationship between them. Floral traits are discussed with respect to early radiation in the order.

METHODS

Floral buds of representatives of Quillajaceae and Surianaceae were dissected and observed using light microscopy and scanning electron microscopy.

KEY RESULTS

Quillajaceae and Surianaceae possess some common traits, such as inflorescence morphology and perianth initiation, but development and organization of their reproductive whorls differ. In Quillaja, initiation of the diplostemonous androecium is unidirectional, overlapping with the petal primordia. In contrast, Suriana is obdiplostemonous, and floral organ initiation is simultaneous. Independent initiation of five carpels is common to both Quillaja and Suriana, but subsequent development differs; the antesepalous carpels of Quillaja become fused proximally and exhibit two rows of ovules, and in Suriana the gynoecium is apocarpous, gynobasic, with antepetalous biovulate carpels.

CONCLUSIONS

Differences in the reproductive development and organization of Quillajaceae and Surianaceae cast doubt on their potential sister relationship. Instead, Quillaja resembles Leguminosae in some floral traits, a hypothesis not suggested by molecular-based phylogenies. Despite implicit associations of zygomorphy with species-rich clades and actinomorphy with species-poor families in Fabales, this correlation sometimes fails due to high variation in floral symmetry. Studies considering specific derived clades and reproductive biology could address more precise hypotheses of key innovation and differential diversification in the order.

Phylogeography of the tree Hymenaea stigonocarpa (Fabaceae: Caesalpinioideae) and the influence of quaternary climate changes in the Brazilian cerrado

BACKGROUND AND AIMS

Hymenaea stigonocarpa (Fabaceae: Caesalpinioideae) is an endemic tree from the Brazilian cerrado (savanna vegetation), a biome classified as a hotspot for conservation priority. This study investigates the phylogeographic structure of H. stigonocarpa, in order to understand the processes that have led to its current spatial genetic pattern.

METHODS

The polymorphism level and spatial distribution of variants of the plastid non-coding region between the genes psbC and trnS were investigated in 175 individuals from 17 populations, covering the greater part of the total distribution of the species. Molecular diversity indices were calculated and intra-specific relationships were inferred by the construction of haplotype networks using the median-joining method. Genetic differentiation among populations and main geographical groups was evaluated using spatial analysis of molecular variance (SAMOVA).

KEY RESULTS

Twenty-three different haplotypes were identified. The level of differentiation among the populations analysed was relatively high (F(ST) = 0.692). Phylogeographic analyses showed a clear association between the haplotype network and geographic distribution of populations, revealing three main geographical groups: western, central and eastern. SAMOVA corroborated this finding, indicating that most of the variation can be attributed to differences among these three groups (58.8 %), with little difference among populations within groups (F(SC) = 0.252).

CONCLUSIONS

The subdivision of the geographic distribution of H. stigonocarpa populations into three genetically differentiated groups can be associated with Quaternary climatic changes. The data suggest that during glacial times H. stigonocarpa populations became extinct in most parts of the southern present-day cerrado area. Milder climatic conditions in the north and eastern portions of the cerrado resulted in maintenance of populations in these regions. Thus it is inferred that the most southern part of the present-day cerrado was re-colonized by different lineages from northern parts of this biome, after postglacial climate amelioration.

Post-zygotic reproductive isolation between sympatric taxa in the Chamaecrista desvauxii complex (Leguminosae-Caesalpinioideae)

BACKGROUND AND AIMS

Differences in the mating systems and the mechanisms of reproductive isolation between Chamaecrista desvauxii var. graminea and C. desvauxii var. latistipula were examined in the Chapada Diamantina, Brazil. These taxa occur sympatrically, and their populations demonstrate marked morphological differences. The objective of the present work was to determine if reproductive isolation mechanisms exist between these two populations of C. desvauxii, and to determine the influence of these putative mechanisms on their genetic differentiation.

METHODS

Field observations were made of floral biology, phenology and floral visitation, and experiments on intra- and interpopulation pollination and germination rates of the resultant seeds were performed. A genetic examination of the populations was undertaken using four allozyme loci.

KEY RESULTS

The varieties examined demonstrated overlapping of flowering periods during the months of June to September. The main pollinator for both varieties was the bee Bombus brevivillus. Both varieties are self-compatible, and a large number of fruits are formed in cross-pollinations with high seed germination rates. Inter-taxa pollinations result in high levels of fruit production, but no seeds are formed. Two of the four loci examined were diagnostic for the varieties, and exclusive high-frequency alleles were encountered at the other loci, leading to a high genetic distance between the two populations (0.495).

CONCLUSIONS

Pre-zygotic barriers were not found between the two varieties, and these remain isolated due to post-zygotic events. The two varieties demonstrate marked differences in their morphology, floral biology, phenology and genetic make-up, all of which indicate that they should be treated as two distinct species. A complete revision involving the other varieties of the C. desvauxii complex will be necessary in order to define these two taxa formally.

The unique pollen morphology of Duparquetia (Leguminosae: Caesalpinioideae): developmental evidence of aperture orientation using confocal microscopy

BACKGROUND AND AIMS

The phylogenetic affinities of the aberrant monotypic genus Duparquetia (subfamily Caesalpinioideae) are at present unresolved. Preliminary results from molecular analyses suggest a basal, isolated position among legumes. A study of Duparquetia pollen was carried out to provide further morphological characters to contribute to multi-data set analyses. Understanding the development of Duparquetia pollen was necessary to clarify the orientation of the apertures.

METHODS

Pollen grains and developing microspores were examined using light microscopy, confocal microscopy and scanning electron microscopy. Evidence for the orientation of the apertures was provided by the examination of microspores within developing tetrads, using (a) confocal microscopy to locate the position of the ectoapertures, and (b) light microscopy and Alcian blue stain to locate the position of the endoapertures.

KEY RESULTS

Confocal microscopy has been used for the first time to examine developing microspores in order to obtain information on ectoapertures that was unavailable using other techniques. Pollen in Duparquetia develops in tetrahedral tetrads as in other eudicots, with the apertures arranged in a modified pattern following Fischer's rule. Pollen grains are asymmetrical and have one equatorial-encircling ectoaperture with two equatorial endoapertures, a unique feature in Leguminosae, and in eudicots.

CONCLUSIONS

The pollen morphology of Duparquetia is so unusual that it provides little information to help determine its closest relatives. However, it does fit with a pattern of greater pollen morphological diversity in the first-branching caesalpinioid legume groups than in the more derived clades. The latitudinal ectoaperture of Duparquetia is unique within the Fabales and eudicot clades, resembling more closely the monosulcate pollen found in monocots and basal angiosperms; however, developmental patterns are recognizably similar to those of all other legume pollen types.

New aspects in floral development of Papilionoideae: initiated but suppressed bracteoles and variable initiation of sepals

BACKGROUND AND AIMS

The increase of molecular data and the resulting insights into legume systematics make the search for new morphological characters and a careful re-investigation of already stated characters necessary. Bracteoles are small, reduced leaves borne close to the base of lateral branches. Although they seem unimportant in older buds, they have an ecological function in protecting the sepal primordia. Furthermore, a morphogenetic function in mediating the onset of sepal initiation is suspected in the literature. The occurrence of bracteoles varies within Papilionoideae, and their distribution is used in legume systematics. But this is open to criticism, because there is a tendency to use 'absent' for 'caducous'. Thus attention here was paid to the initiation of bracteoles as well as to the sequence of sepal initiation.

METHODS

The floral development of 30 taxa out of 15 tribes of Papilionoideae was investigated using scanning electron microscopy (SEM).

KEY RESULTS

In five taxa the bracteoles initiated, but suppressed early. Furthermore, a broad variability of sepal initiation was found. Besides the widely stated unidirectional pattern, modified unidirectionality, tendencies towards whorled, fully whorled, bidirectional and successive initiation of sepals were all found.

CONCLUSION

Initiated but suppressed bracteoles are presented as a 'new' character in Papilionoideae. Considering the presence of bracteoles as a plesiomorphy, their suppression can be seen as a step towards completely reduced bracteoles. The remarkable variability of the sequence of sepal initiation questions the widely stated unidirectionality of organ initiation in Papilionoideae. The different modes of sepal initiation are deducible from the helical pattern of some caesalpinioids, which is seen as a developmental link of the flowers of Papilionoideae and Caesalpinioideae. The bidirectional sepal initiation is possibly a consequence of the morphogenetic function of bracteoles, although bidirectionality is not found in all taxa with reduced bracteoles.

Structure of pollen apertures in the Detarieae sensu stricto (Leguminosae: Caesalpinioideae), with particular reference to underlying structures (Zwischenkörper)

This study presents the pollen aperture morphology of 148 out of approx. 200 species in 16 genera of the Detarieae s.s. and 13 related genera, investigated with light microscopy, scanning electron microscopy and transmission electron microscopy, using various staining techniques. Features of detarioid legume pollen apertures are described, illustrated and discussed in relation to function and phylogeny. Protruding apertures in the mature pollen grains of taxa in the Detarieae s.s are associated with underlying structures composed of pectic substances called 'Zwischenkörper'. This is the first report of Zwischenkörper in legume pollen. A review of previous literature on Zwischenkörper, evidence of how they differ from onci, and a discussion of developmental origins, terminology and function, is given. Zwischenkörper occur in pollen of Daniellia, Eurypetalum, Eperua, Augouardia, Stemonocoleus, Baikiaea, Copaifera, Pseudosindora, Detarium, Sindora, Sindoropsis, Tessmannia, Gilletiodendron, Hylodendron, Hymenaea, Peltogyne and Guibourtia of the Detarieae s.s. clade of recent molecular analyses. Exinous projections and/or bridges are present over the centre of apertures in the pollen of Sindora, Copaifera, Detarium, Pseudosindora, Hylodendron and Sindoropsis, and may cover the Zwischenkörper of live pollen. Zwischenkörper also occur in the closely related genus Barnebydendron, the sister genus to the Detarieae s.l. clade Goniorrhachis, and also Cercis of the sister clade to the Detarieae s.l. plus Goniorrhachis. A modified form of Zwischenkörper occurs in the pollen of Schotia. Zwischenkörper were not detected in the genera Colophospermum, Prioria, Gossweilerodendron, Oxystigma, Kingiodendron and Hardwickia of the Prioria clade, or in Endertia, Lysidice and Saraca of the Amherstieae clade. None of these taxa have protruding apertures.

chitwoodi

Legumes of the genera Astragalus (milkvetch), Coronilla (crownvetch), Lathyrus (pea vine), Lotus (birdsfoot trefoil), Medicago (alfalfa), Melilotus (clover), Trifolium (clover), and Vicia (common vetch) were inoculated with a population of Melaidogyne chitwoodi from Utah or with one of three M. hapla populations from California, Utah, and Wyoming.Thirty-nine percent to 86% of alfalfa (M. scutellata) and 10% to 55% of red clover (T. pratense) plants survived inoculation with the nematode populations at a greenhouse temperature of 24 +/- 3 degrees C. All plants of the other legume species survived all nematode populations, except 4% of the white clover (T. repens) plants inoculated with the California M. hapla population. Entries were usually more susceptible to the M. hapla populations than to M. chitwoodi. Galling of host roots differed between nematode populations and species. Root-galling indices (1 = none, 6 = severely galled) ranged from 1 on pea vine inoculated with the California population of M. hapla to 6 on yellow sweet clover inoculated with the Wyoming population of M. hapla. The nematode reproductive factor (Rf = final nematode population/initial nematode population) ranged from 0 for all nematode populations on pea vine to 35 for the Wyoming population of M. hapla on alfalfa (M. sativa).