A Chewable Cure "Kanna": Biological and Pharmaceutical Properties of Sceletium tortuosum.

Sceletium tortuosum (L.) N.E.Br. (Mesembryanthemaceae), commonly known as kanna or kougoed, is an effective indigenous medicinal plant in South Africa, specifically to the native San and Khoikhoi tribes. Today, the plant has gained strong global attraction and reputation due to its capabilities to promote a sense of well-being by relieving stress with calming effects. Historically, the plant was used by native San hunter-gatherers and Khoi people to quench their thirst, fight fatigue and for healing, social, and spiritual purposes. Various studies have revealed that extracts of the plant have numerous biological properties and isolated alkaloids of Sceletium tortuosum are currently being used as dietary supplements for medicinal purposes and food. Furthermore, current research has focused on the commercialization of the plant because of its treatment in clinical anxiety and depression, psychological and psychiatric disorders, improving mood, promoting relaxation and happiness. In addition, several studies have focused on the isolation and characterization of various beneficial bioactive compounds including alkaloids from the Sceletium tortuosum plant. Sceletium was reviewed more than a decade ago and new evidence has been published since 2008, substantiating an update on this South African botanical asset. Thus, this review provides an extensive overview of the biological and pharmaceutical properties of Sceletium tortuosum as well as the bioactive compounds with an emphasis on antimicrobial, anti-inflammatory, anti-oxidant, antidepressant, anxiolytic, and other significant biological effects. There is a need to critically evaluate the bioactivities and responsible bioactive compounds, which might assist in reinforcing and confirming the significant role of kanna in the promotion of healthy well-being in these stressful times.

Comparative Analyses of the Self-Sealing Mechanisms in Leaves of Delosperma cooperi and Delosperma ecklonis (Aizoaceae).

Within the Aizoaceae, the genus Delosperma exhibits a vast diversification colonizing various ecological niches in South-Africa and showing evolutionary adaptations to dry habitats that might include rapid self-sealing. Leaves of Delosperma react to external damage by the bending or contraction of the entire leaf until wound edges are brought into contact. A study of leaf morphology and anatomy, biomechanics of entire leaves and individual tissues and self-sealing kinematics after a ring incision under low and high relative humidity (RH) was carried out comparing the closely related species Delosperma cooperi and Delosperma ecklonis, which are indigenous to semi-arid highlands and regions with an oceanic climate, respectively. For both species, the absolute contractions of the examined leaf segments ("apex", "incision", "base") were more pronounced at low RH levels. Independent of the given RH level, the absolute contractions within the incision region of D. cooperi were significantly higher than in all other segments of this species and of D. ecklonis. The more pronounced contraction of D. cooperi leaves was linked mainly to the elastic properties of the central vascular strand, which is approximately twice as flexible as that of D. ecklonis leaves.

Best of both worlds: simultaneous high-light and shade-tolerance adaptations within individual leaves of the living stone Lithops aucampiae.

"Living stones" (Lithops spp.) display some of the most extreme morphological and physiological adaptations in the plant kingdom to tolerate the xeric environments in which they grow. The physiological mechanisms that optimise the photosynthetic processes of Lithops spp. while minimising transpirational water loss in both above- and below-ground tissues remain unclear. Our experiments have shown unique simultaneous high-light and shade-tolerant adaptations within individual leaves of Lithops aucampiae. Leaf windows on the upper surfaces of the plant allow sunlight to penetrate to photosynthetic tissues within while sunlight-blocking flavonoid accumulation limits incoming solar radiation and aids screening of harmful UV radiation. Increased concentration of chlorophyll a and greater chlorophyll a:b in above-ground regions of leaves enable maximum photosynthetic use of incoming light, while inverted conical epidermal cells, increased chlorophyll b, and reduced chlorophyll a:b ensure maximum absorption and use of low light levels within the below-ground region of the leaf. High NPQ capacity affords physiological flexibility under variable natural light conditions. Our findings demonstrate unprecedented physiological flexibility in a xerophyte and further our understanding of plant responses and adaptations to extreme environments.

A phylogenetic hypothesis for the recently diversified Ruschieae (Aizoaceae) in southern Africa.

The Ruschieae is a large tribe of about 1600 species of succulent perennials. They form a major component of the arid parts of the Greater Cape Floristic Region, both in numbers of species and in their density of coverage. So far phylogenetic relationships within the tribe have been unresolved, largely through the paucity of variable molecular characters and this is ascribed to the tribe's recent and rapid radiation. Our phylogeny is based on 10 chloroplast gene regions and represents a nearly complete sampling of the 100 currently recognised genera of the Ruschieae. These chloroplast regions yielded relatively few phylogenetically informative characters, consequently providing only limited resolution in and poor support for many parts of the phylogeny. Nevertheless, for the first time, we provide well-supported evidence that taxa with mostly mesomorphic, often ephemeral leaves and weakly persistent fruits form a basal grade of lineages in the Ruschieae. These lineages subtend a large polytomy of taxa with almost exclusively xeromorphic, persistent leaves and strongly persisting fruits. Among the basal grade of lineages, those occurring within the winter-rainfall region typically shed their leaves or form (at least partly) a protective, dry sheath around the apical bud during the dry summer months, as a means of escaping the summer drought. This contrasts with taxa of the basal grade from outside the winter-rainfall region, in which the leaves persist. Our results show that, in both strongly and weakly persistent fruits, specialised characteristics of the fruit evolved repeatedly and so these structures are highly homoplasious. Perhaps as a consequence of repeated changes towards increased persistence and specialisation of leaves and fruits, several clades show little morphological cohesion. However, as in other groups in the Cape Flora, most clades in the Ruschieae represent regional groupings. Our analysis of sequences of the nuclear gene 'chloroplast-expressed glutamine synthetase' (ncpGS) revealed extensive paralogy within the Ruschieae, but found an intact reading frame in all its members. More data on the cytology of the Ruschieae is needed to evaluate whether the paralogy observed is due to gene duplication or polyploidy.

'Living stones' reveal alternative petal identity programs within the core eudicots.

Petals, defined as the showy laminar floral organs in the second floral whorl, have been shown to be under similar genetic control in distantly related core eudicot model organisms. On the basis of these findings, it is commonly assumed that the petal identity program regulated by B-class MADS-box gene homologs is invariant across the core eudicot clade. However, the core eudicots, which comprise >70% of angiosperm species, exhibit numerous instances of petal and sepal loss, transference of petal function between floral whorls, and recurrent petal evolution. In the face of these complex patterns of perianth evolution, the concept of a core eudicot petal identity program has not been tested. We therefore examined the petal identity program in the Caryophyllales, a core eudicot clade in which perianth differentiation into sepals and petals has evolved multiple times. Specifically, we analyzed the expression patterns of B- and C-class MADS-box homologs for evidence of a conserved petal identity program between sepal-derived and stamen-derived petaloid organs in the 'living stone' family Aizoaceae. We found that neither sepal-derived nor stamen-derived petaloid organs exhibit gene expression patterns consistent with the core eudicot petal identity program. B-class gene homologs are not expressed during the development of sepal-derived petals and are not implicated in petal identity in stamen-derived petals, as their transient expression coincides with early expression of the C-class homolog. We therefore provide evidence for petal development that is independent of B-class genes and suggest that different genetic control of petal identity has evolved within this lineage of core eudicots. These findings call for a more comprehensive understanding of perianth variation and its genetic causes within the core eudicots--an endeavor that will have broader implications for the interpretation of perianth evolution across angiosperms.

Sodium instead of potassium and chloride is an important macronutrient to improve leaf succulence and shoot development for halophyte Sesuvium portulacastrum.

Soil salinity is contributed largely by NaCl but some halophytes such as Sesuvium portulacastrum have evolved to adapt salinity environment and demonstrate optimal development under moderate salinity. To elucidate the detail mechanisms of the great salt tolerance and determine the respective contributions of Na(+), K(+) and Cl(-) on the development of S. portulacastrum, morphological and physiological analysis were performed using plants supplied with 200 mM of different ions including cations (Na(+), K(+), Li(+)) and anions (Cl(-), NO(3)(-), Ac(-)) respectively. The results revealed that the salt-treated plants accumulated large amounts of sodium in both leaf and stem. There was a greater shoot growth in presence of external Na(+) compared to K(+) and Cl(-). Na(+) was found more effective than K(+) and Cl(-) in cell expansion, leaf succulence, and shoot development. Flame emission and X-Ray microanalysis revealed the relative Na(+) content was much higher than K(+) and Cl(-) in both leaf and stem of well developed S. portulacastrum, leading to a higher Na(+)/K(+) ratio. The effects of different ions on the development of S. portulacastrum were listed as the following: Na(+) > NO(3)(-) > CK > Cl(-) > K(+) > Ac(-) > Li(+). These results demonstrated NaCl toxicity is attributable largely to the effect of Cl(-) but rarely to Na(+), and thus sodium is concluded as a more important macronutrient than potassium and chloride for improving leaf succulence and shoot development of halophyte S. portulacastrum.

Unexpected morphological and karyological changes in invasive Carpobrotus (Aizoaceae) in Provence (S-E France) compared to native South African species.

Hybridization processes can lead to evolutionary changes, particularly in co-introduced congeneric plant species, such as Carpobrotus spp. which are recognized as invasive in Mediterranean climate regions. Morphological and karyological comparisons have therefore been made between native Carpobrotus edulis and C. acinaciformis in South Africa and their invasive counterparts in Provence (C. edulis and C. aff. acinaciformis). Morphological data exhibited the most significant differences in invasive C. aff. acinaciformis that forms a new phenotypic variant. Unexpected chromosomal restructuring has been highlighted for both taxa in Provence, with in particular a clear decrease in asymmetry, an increase in the intraspecific variability, and an interspecific convergence of karyotypes. These changes suggest a drift that has facilitated various crosses, and has been amplified through hybridization/introgression. Furthermore, several morphological and karyological transgressive characters have been found in the two invasive taxa. These results stress the important role and the rapidity of karyological changes in invasive processes.

Invasion dynamics of two alien Carpobrotus (Aizoaceae) taxa on a Mediterranean island: I. Genetic diversity and introgression.

This study, based on morphological and isozyme analysis, clearly discriminates two invasive Carpobrotus taxa, C. edulis and C. acinaciformis, in the Hyères archipelago off the southeastern coast of France. However, three different allelic combinations demonstrate the presence of intermediate individuals resulting from an introgression of part of the C. edulis genome into that of C. acinaciformis. Both taxa have higher than average genetic (C. edulis: P(0.95)=62.5%, A=2.25+/-0.70, H(o)=0.329+/-0.324; C. acinaciformis: P(0.95)=75%, A=2.38+/-0.42, H(o)=0.645+/-0.109) and clonal diversities (C. edulis: IP=0.37; C. acinaciformis: IP=0.48). Furthermore, C. acinaciformis has an excess of heterozygotes (F=-0.585+/-0.217), probably due to introgression. The relationship between the probability of clonal identity for two individuals and distance indicates that C. acinaciformis relies more on clonal reproduction than on sexual recruitment (seed recruitment/vegetative propagation=u/v=0.027), in contrast to C. edulis, whose probability of clonal identity did not vary with distance. The overwhelming clonal growth and high genetic diversities of C. acinaciformis and the previously recorded invasion potential for C. edulis raises concern for intensified invasion via hybridisation.

Artificial neural networks for species identification by taxonomists.

This paper is a study of the value of applying artificial neural networks (ANNs), specifically a multilayer perceptron (MLP), to identification of higher plants using morphological characters collected by conventional means. A practical methodology is thus demonstrated to enable botanical or zoological taxonomists to use ANNs as advisory tools for identification purposes. A comparison is made between the ability of the neural network and that of traditional methods for plant identification by means of a case study in the flowering plant genus Lithops N.E. Brown (Aizoaceae). In particular, a comparison is made with taxonomic keys generated by means of the DELTA system. The ANN is found to perform better than the DELTA key generator, for conditions where the available data is limited, and species relatively difficult to distinguish.