Different Localities In South Africa Research Articles

Morphological and molecular diagnosis of two new species of Trypanosoma Gruby, 1843 infecting South African cordylid lizards (Squamata: Cordylidae: Cordylinae), Trypanosoma (Squamatrypanum) ndumoensis n. sp. and Trypanosoma (Trypanosoma) tokoloshi n. sp.

Despite reptile trypanosomes forming a large group, the majority of species descriptions are data deficient, lacking key characteristic data and supporting molecular data. Reptile hosts show potential to facilitate transmission of zoonotic trypanosomiases and offer key information to understanding the genus of Trypanosoma. Several species of squamates from different localities in South Africa were screened molecularly and microscopically for trypanosomes in the present study. Based on the combination of morphological and molecular analyses, two new species of Trypanosoma, Trypanosoma (Squamatrypanum) ndumoensis n. sp. and Trypanosoma (Trypanosoma) tokoloshi n. sp., infecting South African cordylid lizards (Cordylidae: Cordylinae) are described in this study. The first molecular data for a South African reptile trypanosome is provided herewith.

Performance of Selected South African Kaolinitic Clays for Limestone Calcined Clay Cement

Limestone calcined clay cement (LC3) has considerable potential for large-scale implementation. We investigated three selected kaolinitic clays at different locations in South Africa. LC3 mortars were compared to Portland cement mortar as control, particularly the hydration phase mineralogy/content, microstructure, compressive strength, and 3D void structure. The investigation indicated that similar pozzolanic oxide (SiO2 + Al2O3) could be obtained from calcined clay of varied kaolinite content. While kaolinite content improves the pozzolanic activity, consistency, and compressive strength of the mortar, the void refinement at the microscale depends on the degree of limestone filling/hydration. The hydration phase contents, microstructure, mineralogy, and porosity of the processed kaolinitic clays were determined to be adequate. However, it is noted that the intrinsic content of limestone (and gypsum) in commercially available Portland cement should be considered for equivalent clinker, limestone, and gypsum contents of 50%, 15%, and 5%, respectively.

Wind and wind power characteristics of the eastern and southern coastal and northern inland regions, South Africa.

The objective of this work is to understand the fluctuating nature of wind speed characteristics on different time scales and to find the long-term annual trends of wind speed at different locations in South Africa. The hourly average mean wind speed values over a period of 20 years are used to achieve the set objective. Wind speed frequency, directional availability of maximum mean wind speed, total energy, annual energy yield and plant capacity factors are determined for seven locations situated both inland and along the coast of South Africa. The highest mean wind speed (6.01 m/s) is obtained in Port Elizabeth and the lowest mean wind speed (3.86 m/s) is obtained in Bloemfontein. Wind speed increased with increasing latitudes at coastal sites (Cape Town, Durban, East London and Port Elizabeth), while the reverse trend was observed at inland locations (Bloemfontein, Johannesburg and Pretoria). Noticeable annual changes and relative wind speed values are found at coastal locations compared to inland sites. The energy pattern factor, also known as the cube factor, varied between a minimum of 1.489 in Pretoria and a maximum of 1.858 in Cape Town. Higher energy pattern factor (EPF) values correspond to sites with fair to good wind power potential. Finally, Cape Town, East London and Port Elizabeth are found to be good sites for wind power deployments based on the wind speed and power characteristics presented in this study.

Serpentinization in the Archean and Early Phanerozoic – Insights from chromium isotope and REY systematics of the Mg[sbnd]Cr hydroxycarbonate stichtite and associated host serpentinites

Chromium isotopes have emerged as powerful redox proxies for past ocean-atmosphere systems as shifts in Cr isotope ratios towards heavier isotope compositions are indicative of Cr redox cycling on Earth. Knowledge of the Cr cycle in the critical zone and the fate of Cr during serpentinization and other hydrothermal processes is therefore important to assess the geologic interpretation of Cr isotopes in the rock record. An investigation of the trace element geochemistry of stichtite may provide such insights by shedding new light on the conditions of past serpentinizing environments.Stichtite, a magnesium‑chromium-bearing hydroxycarbonate, is a rare mineral that forms during serpentinization by conversion of chromite and other Cr-rich spinels. Its occurrence is restricted to Archean and Early Phanerozoic serpentinite bodies on ancient cratons and to mine waste. In this contribution, Cr isotope and rare earth elements and Y (REY) systematics in stichtites and their respective serpentinite hosts were investigated. This comparative study of Archean and Early Phanerozoic stichtites from different localities in South Africa, Western Australia, and Tasmania revealed variable Cr isotope fractionation with δ53Cr ranging from −0.145 ± 0.052‰ up to +0.24 ± 0.04‰ in the stichtites. The serpentinites are less fractionated with δ53Cr ranging from −0.13 ± 0.04‰ to +0.05 ± 0.02‰ and show a fractionation similar to the terrestrial mantle δ53Cr inventory. Whereas δ53Cr of all stichtites, except of one, are within the chromite array, the deviations from host serpentinites indicate that Cr was subject to Cr cycling during serpentinization. The variable Cr isotope ratios of stichtite reflect a complex interplay of several physicochemical processes. These are difficult to identify solely from isotope compositions as the resulting Cr isotope fractionation represents the net result of all processes that affect the complex Cr cycling in the critical zone.The very first REY concentration data for stichtite further corroborate the notion that stichtite formation is indeed not an isochemical process and that its formation involves intense metal mobility during associated metasomatism. Rare earth elements and yttrium are depleted in the stichtites relative to the serpentinites, but the overall similar REYCN patterns indicate that the REY in both, the serpentinites and stichtites, were sourced from a chemically similar fluid that was dominated by interaction with the serpentinized rocks. Seawater and marine carbonates can be excluded as potential contributors towards REY inventory of stichtite. The presence of superchondritic Y/Ho ratios in stichtite further emphasizes intense water-rock interaction at high CO32− and HCO3− activities. Positive EuCN anomalies in some stichtites and serpentinites point to reducing conditions with regard to the Eu3+/Eu2+ redox couple and temperatures in excess of 250 °C at the site of REY mobilization, prior to stichtite formation. Lack of Ce anomalies in stichtite further confirm reducing conditions at the site of stichtite formation.

Croton gratissimus - essential oil composition and chemometric analysis of an ethnomedicinally important tree from South Africa

Croton gratissimus Burch. is widely used in traditional medicine to treat a range of conditions including malaria, hypertension, diabetes, arthritis, urinary tract infections, gonorrhoea and impotence. The young branches and leaves are pleasantly aromatic, and it is recorded that various ethnic groups in South Africa used the leaves as a perfume. The chemistry of the non-volatile constituents has been widely investigated. However, little scientific data on the volatile constituents are available. Essential oils (EOs) were obtained by hydrodistillation from the leaves and twigs (n = 62) collected at different locations in South Africa. The hydrodistilled oils were analysed with gas chromatography coupled simultaneously to a mass spectrometer (MS) and a flame ionisation detector (FID). GC–MS/FID of the EOs showed the presence of mono- and sesquiterpenes as the major class of compounds. The most abundant compounds were β-pinene (nd–13.7%), sabinene (0.2–16.7%), α-phellandrene (0.4–44.3%), Z-β-ocimene (0.2–12.5%), limonene (0.2–38.3%), p-cymene (0.1–25.2%), phytol (nd–24.9%) and oxidohimachalene (nd–54.6%). Untargeted analysis of the GC–MS data was performed using SIMCA-P + 14.0, and different methods were used to explore possible chemical variation in the data set. After principal component analysis (PCA), the hierarchical cluster analysis (HCA) revealed three major chemotypes. Loadings and contribution plots identified oxidohimachalene as the main chemical marker for chemotype 1. Chemotype 2 was dominated by α-phellandrene, α-pinene and p-cymene, while chemotype 3 was characterised by low yields of α-phellandrene and oxidohimachalene. This study revealed mostly quantitative rather than qualitative variation in the EOs constituents of C. gratissimus.

Mass developments of Euglena sanguinea Ehrenberg in South Africa

Blooms of Euglena sanguinea Ehrenberg were observed at two different locations in South Africa, Mpumalanga province during 2016 and Limpopo province during 2020. Besides being responsible for a blood-red discolouration of the water, the species is also toxic, causing fish mortalities. Samples from South Africa were dominated by E. sanguinea and very low concentrations and diversity of other algal species were present. Microscopic studies revealed that the size ranges and the morphology of the cells corresponded to descriptions of the species in literature. High quality micrographs, illustrating the general cell structure and most features used for accurate identification, are provided. Intensive literature searches allowed mapping of the worldwide geographical distribution of the species, which revealed that it was sparsely distributed throughout Africa, because it was reported from only seven countries. Only one previous record of its presence in experimental ponds in South Africa exists, rendering this study a second record for its presence in the country.

Evaluation of apple rootstocks planted in different locations in South Africa

Evaluation of apple rootstocks planted in different locations in South Africa

High diversity and low host-specificity of Termitomyces symbionts cultivated by Microtermes spp. indicate frequent symbiont exchange

Abstract Fungus-growing termites (subfamily Macrotermitinae) live in an obligate mutualistic symbiosis with species of the fungal genus Termitomyces (Basidiomycota). Although the species that build large mounds are the most conspicuous, termites of the genus Microtermes construct large underground networks of tunnels connecting many fungus gardens. They are also the only entire genus within the Macrotermitinae in which vertical transmission of the fungal symbiont has evolved. To study patterns of genetic diversity in species of the genus Microtermes and their Termitomyces symbionts, we sampled at three different locations in South Africa and sequenced COI for the termites and ITS for the fungi. We discovered high genetic diversity in both termites and fungal symbionts but very low interaction specificity. This implies that frequent horizontal exchange of fungal symbionts occurs between species, despite vertical transmission across generations. We also estimated colony size based on termite haplotype and fungal genotype combinations and found indications that colonies may extend over large areas.

Bioactive constituents of Lobostemon fruticosus: Anti-inflammatory properties and quantitative analysis of samples from different places in South Africa

Lobostemon fruticosus is South Africa medicinal plant traditionally used in treatment of wounds and skin diseases. Nevertheless, there is no report on its phytochemical constituents. LC–LTQ-Orbitrap mass spectrometry was used for identification and quantification of its constituents. A total of 13 compounds were identified from the leaves and twigs of the plant using NMR, ESI-HRMS and reference substances. The identified compounds were p-hydroxybenzoic acid (1), lycopsamine-N-oxide (2), caffeic acid (3), loliolide (4), 3-indolcarbaldehyde (5), globoidnan B (6), rabdosiin (7), syringaresinol (8), pinoresinol (9), rutin (10), rosmarinic acid (11), keampferol-3-O-rutinoside (12) and globoidnan A (13). In addition, quantitative determination of 6 marker compounds in samples from 12 different locations in South Africa was established. Rosmarinic acid and globoidnan A were found in large amount in the leaves and flowers of the plant. Samples from West Cape contained relatively greater amount of the tested compounds per dry weight than the other samples. The anti-inflammatory activities of isolated compounds were assessed by measuring the levels of cytokines IL-1β, IL-2, IL-6, GM-CSF and TNF-α in the supernatant media of human peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS). At a concentration of 100 μM, compounds 7, 8 and 11 significantly decreased secretion of IL-1β, IL-2 and IL-6 compared to the LPS treated control (0.76–57.6%). All compounds significantly reduced the production of TNF-alpha compared to the LPS treated control (0.17–12.2%) and reference drug ibuprofen.

Phytochemical Contents and Antioxidant Capacity of the Leaves of Aloe greatheadii var. davyana from Four South African Provinces

The current study was aimed at the determination of the phytochemical contents and antioxidant capacity of the leaves of A. greatheadii from four provinces of South Africa. The leaves samples of A. greatheadii were collected at four different locations in South Africa; namely, Limpopo province (Polokwane), Gauteng province (Ga-Rankuwa), Mpumalanga province (Siyabuswa) and North-West province (Brits) during the summer season of the year. The ground samples were then extracted in a serial sequential procedure with different organic solvents using cold maceration extraction method. The extracts were then subjected to quantitative phytochemical analysis for the determination of total phenolic, total tannin, total flavonoid and total saponin content. In addition, the antioxidant capacity of the methanol extracts were evaluated through the DPPH assay. Quantitative phytochemical analysis showed variation in the total phenolic, total tannin, total flavonoid and total saponin contents of the samples from different locations, with specific phytochemicals found in higher amounts at different locations. However, upon calculation of the total phytochemical content the high amount was recorded with the Limpopo province sample. Variation in the antioxidant capacity (EC50 based) of the samples from different locations was demonstrated, with the Limpopo and Mpumalanga provinces’ samples showing high capacity. The results demonstrated that the variation in geographical locations has an effect on the phytochemical contents and antioxidant capacity of the leaves of A. greatheadii. Furthermore, the Limpopo province area with a high altitude appeared to be providing suitable growing conditions for high accumulation of phytochemicals and higher antioxidant capacity.

Investigation of various aerosols over different locations in South Africa using satellite, model simulations and LIDAR

Decadal studies (2004–2014) of various aerosols were carried out over South Africa (SA) using various satellite data and model simulations. The aerosols investigated included black carbon (BC), sulphate, dust and marine aerosols. BC aerosols were observed to be dominant in the northeastern parts of SA while sulphate aerosols were dominant in eastern parts of the country. Seasonal studies revealed that BC aerosols were more dominant in the eastern parts of SA during spring and less dominant in autumn. Sulphate also showed dominance in the eastern parts of SA during summer and less dominance in winter. The high sulphate concentration in summer is a result of an increase in relative humidity which favours the production of sulphates. Air masses from the north and northeastern parts of the subcontinent were responsible for the transport of BC resulting from biomass burning into SA. The Goddard Chemistry Aerosol Radiation and Transport model indicated that there was no significant change in the sulphate aerosol trends from 2004 to 2007. The highest sulphate aerosol levels were observed in the summer whilst the lowest sulphate aerosol levels were observed in winter. The Council for Scientific and Industrial Research (CSIR) Light Detection and Ranging (LIDAR) was used to carry out measurements in Lephalale during July 10–18, 2014. Aerosol extinction co‐efficient profiles were retrieved by the CSIR mobile LIDAR and were compared to aerosol extinction co‐efficient profiles retrieved from the Cloud‐Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO). The aerosol extinction co‐efficients of 0.26 and 0.17/km on July 14 and 16, 2014, respectively could be identified as dust aerosols.

Characterization of Ralstonia strains infecting tomato plants in South Africa

Ralstonia spp., the causal agents of bacterial wilt, cause severe yield losses of Solanaceous crops, including tomato. The disease is difficult to control due to the pathogen's ability to survive in soil and to cause latent infections. Therefore, characterizing Ralstonia strains is important in developing effective strategies for diagnoses, quarantine and selection of biocontrol agents. In this study, 50 Ralstonia strains previously isolated from wilted tomato plants in different locations in South Africa were obtained from the culture collection of the Agricultural Research Council, Pretoria, and private seed companies. A phylogenetic analysis of the endoglucanase gene sequences revealed that 49 strains were R. pseudosolanacearum and only one was R. solanacearum. R. pseudosolanacearum strains grouped into two sequevars, 18 and 31, while the single R. solanacearum strain grouped into the cold-adapted sequevar 1, also known as race 3 biovar 2. The pathogenicity results revealed that the selected strains were pathogenic on tomato seedlings. This study thus revealed that bacterial wilt of tomato is caused primarily by R. pseudosolanacearum, but R. solanacearum IIB-1 is also present in South Africa. This information is relevant in terms of the implementation of quarantine measures, notably to put into place measures that will prevent the introduction of strain IIB-1 into other provinces of South Africa.

Potential Herb-Drug Pharmacokinetic Interactions between African Wild Olive Leaf Extract and Selected Antihypertensive Drugs.

The African wild olive (Olea europaea subsp. africana) is traditionally used as a hypotensive agent. Herb-drug interactions may result from the concurrent use of herbal medicines and conventional prescription drugs. This aspect was investigated by determining the effect of the extract on the in vitro intestinal epithelial permeation of selected hypotensive drugs using the Caco-2 cell culture model. The phytochemical profiles of leaf extracts of African wild olive from different localities in South Africa were compared, since efficacy is determined by the chemical composition. Extracts were analysed using ultra-performance liquid chromatography. The oleuropein concentration varied considerably from below the detection limit (4.94 µg/mL) to 59.4 mg/g dry weight. Chemometric models constructed from the aligned chromatographic data indicated only quantitative differences between the profiles. The leaf extract was found to increase the permeability of propranolol in the absorptive direction (Papp = 8.93 × 10-6 cm/s) across Caco-2 cell monolayers, but considerably decreased transport in the secretory direction (Papp = 3.68 × 10-6 cm/s). The permeation of diltiazem was enhanced by the extract in both the absorptive (Papp = 7.33 × 10-6 cm/s) as well as in the secretory direction (Papp = 7.16 × 10-6 cm/s), but a decrease in the efflux ratio was observed. The extract therefore caused a net increase in the transport of both drugs in the absorptive direction due to an inhibition effect on their efflux. This suggests a potential increase in the blood levels of these drugs when taken simultaneously with African wild olive leaf extract, indicating potential adverse effects that must be verified in vivo.

Predicting clear-sky global horizontal irradiance at eight locations in South Africa using four models

Solar radiation under clear-sky conditions provides information about the maximum possible magnitude of the solar resource available at a location of interest. This information is useful for determining the limits of solar energy use in applications such as thermal and electrical energy generation. Measurements of solar irradiance to provide this information are limited by the associated cost. It is therefore of great interest and importance to develop models that generate these data in lieu of measurements. This study focused on four such models: Ineichen-Perez (I-P), European Solar Radiation Atlas model (ESRA), multilayer perceptron neural network (MLPNN) and radial basis function neural network (RBFNN) models. These models were calibrated and tested using solar irradiance data measured at eight different locations in South Africa. The I-P model showed the best performance, recording relative root mean square errors of less than 2% across all hours, months and locations. The performances of the MLPNN and RBFNN were poor when averaged over all stations, but tended to show performance similar to that of the I-P model for some of the stations. The ESRA model showed performance that was in between that of the Artificial Neural Networks and that of the I-P model.

Alternaria toxins in South African sunflower seeds: cooperative study.

Sunflower seed samples (N=80) from different sunflower cultivars originating from different localities in South Africa were analyzed for 15 toxins produced by fungi of the genus Alternaria by means of a simple one-step extraction dilute-and-shoot HPLC-MS/MS approach. References for valine-tenuazonic acid (Val-TeA), altenusin (ALTS), and altenuisol (ALTSOH) were isolated from fungal culture extracts and spectroscopically characterized. Additionally, valine-tenuazonic acid was tested regarding its cytotoxicity in comparison with tenuazonic acid (TeA) and showed less activity on HT-29 cells. Furthermore, alternariol monomethyl ether-3-O-ß-D-glucoside (AME-3G) was produced by fermentation of alternariol monomethyl ether (AME) with the fungus Rhizopus oryzae. The seed samples were analyzed both with and without hulls. The method covers the AAL toxins TA1 and TA2, altenuene (ALT) and iso-altenuene (iso-ALT), altenuisol, altenusin, altertoxin I (ATX-I) and altertoxin II (ATX-II), alternariol (AOH) and alternariol monomethyl ether, alternariol monomethyl ether-3-O-ß-D-glucoside, tenuazonic acid, allo-tenuazonic acid (allo-TeA) and valine-tenuazonic acid, and tentoxin (TEN). More than 80% of the samples were positive for one or more analytes above the respective limit of detection (0.2-23μg/kg). Alternariol, its monomethyl ether, tentoxin, tenuazonic acid, altenuisol, and valine-tenuazonic acid were found in quantifiable amounts. The highest prevalences were found for tentoxin (73% positive, mean content 13.2μg/kg, maximum level 130±0.9μg/kg) followed by tenuazonic acid (51% positive, mean content 630μg/kg, maximum level 6300±560μg/kg). The obtained data were further analyzed statistically to identify quantitative or qualitative relationships between the levels of Alternaria toxin in the samples.

Finding the missing link: Resolving the Coryneliomycetidae within Eurotiomycetes.

Species belonging to the Coryneliaceae and parasitizing Podocarpaceae hosts were collected from different locations in South Africa and studied morphologically by light microscopy and molecularly by obtaining partial nrDNA (ITS-1/5.8S/ITS-2, 18S and 28S) gene sequences. The position of the Coryneliaceae within the Eurotiomycetidae was not confirmed and a new subclass, Coryneliomycetidae, was introduced. While Eurotiomycetidae usually form cleistothecia/gymnothecia with evanescent, unitunicate asci, and Chaetothyriomycetidae mostly perithecia with bitunicate/fissitunicate to evanescent asci, Coryneliomycetidae form pseudothecial mazaedial ascomata, initially with double-walled asci with the outer layer deliquescing, resulting in passive ascospore release. The Coryneliomycetidae thus occupies a unique position in the Eurotiomycetes. Furthermore, epitypes were designated for Corynelia uberata, the type species of Corynelia (type genus of the family, order and subclass), Lagenulopsis bispora, the type species of Lagenulopsis, and Tripospora tripos the type species of Tripospora, with Lagenulopsis and Tripospora confirmed as belonging to the Coryneliaceae. Corynelia uberata resolved into three clades, one on Afrocarpus (= Podocarpus) falcatus and A. gracilior, and two clades occurring on P. latifolius, herein described as C. africana and C. fructigena. Morphologically these three species are not readily distinguishable, although they differ in spore dimensions, ascomata shape, ornamentation and DNA phylogeny. It is likely that several more species from other parts of the world are currently erroneously placed in C. uberata.

Chemical variation of Sceletium tortuosum specimens – NMR fingerprinting and chemometric approach

Sceletium tortuosum (L.) N.E. Br. (Mesembryanthemaceae) is a succulent plant, mainly found in South Africa. The plant has been traditionally used for treatment of CNS-associated conditions, for quenching thirst and relieving hunger. Various Sceletium products are currently marketed with claims of psychoactive properties, such as, mood uplifting and reduction of anxiety. Quality control has been a great challenge in dealing with botanicals. Safety and efficacy of botanical products are dependent on the chemical composition in the plant materials. The extent of phytochemical variation in S. tortuosum specimens collected from different locations in South Africa was investigated by using an NMR-based metabolomics approach in the present study. Significant metabolite variation was observed in the Sceletium plant samples. Geographic location appears to be one of factors that affect the metabolite variations.

Essential oil variation of Tagetes minuta in South Africa – A chemometric approach

Tagetes minuta L., generally known as wild marigold and locally as “Kakiebos”, has been used traditionally for medicinal purposes in many countries around the world. South Africa is currently the major producer of Tagetes essential oil which is used in perfumery, cosmetics and aromatherapy. The organoleptic and therapeutic properties of an essential oil are dependent upon the chemical profile of the oil. Tagetes essential oil from India, Egypt and the United Kingdom has been reported to be highly variable. In this study, possible chemotypic variation of South African Tagetes oil was explored. Eighty-three individual plants were collected from twenty-one different localities in South Africa. Essential oils were obtained by hydrodistillation using a Clevenger-type apparatus and the oil yield obtained ranged between 0.38 and 1.52%. The essential oils were analysed by gas chromatography coupled to mass spectrometry with flame ionisation detector (GC–MS‒FID) and the major compounds accounting for >85% of the total composition were identified as: (Z)-β-ocimene (27.9–56.0%), (E)-ocimenone (7.4–37.2%), (Z)-tagetone (1.4–24.9%), dihydrotagetone (n.d.−23.4%), (Z)-ocimenone (4.5–13.9%), limonene (n.d.−6.5%) and (E)-tagetone (n.d.−3.2%). Untargeted analysis of GC–MS data using MarkerLynx® and hierarchical clustering analysis (HCA) revealed two major chemotypes. Further analysis of the two chemotypes using orthogonal projections to latent structures-discriminant analysis (OPLS-DA) identified (E)-tagetone, dihydrotagetone and (Z)-tagetone as characteristic marker constituents for chemotype 1, while chemotype 2 was characterised by (Z)-β-ocimene, (E)-ocimenone and (Z)-ocimenone.

Differentiation of Pelargonium Sidoides and P. Reniforme through a NMR- Based Chemometric Approach

Pelargonium sidoides DC and P. reniforme Curt (Geraniaceae) are indigenous to South Africa where they are widely distributed along coastal and central regions. Their roots have been used as herbal medicines for centuries. The extract from the roots of P. sidoides has been developed and commercialized as an herbal drug (EPs 7630/Umckloabo®) for the treatment of acute upper respiratory tract infections. P. sidoides and P. reniforme can only be distinguished by the shape of leaves and the color of flowers which becomes problematic when the plants die back in autumn. The root material of P. sidoides is often adulterated with P. reniforme and although the Pharmacopeia accepts both species they have not been shown to be equipotent. In the present study, the root samples of P. sidoides (n = 90) and P. reniforme (n = 44) collected from 23 different locations in South Africa were investigated for their differences in the metabolite expression by using NMR profiling and chemometric analysis. Metabolite differences between the two species, as well as the metabolite variations among the samples of the same species were revealed. P. sidoides has higher levels of total coumarins and the quantitative difference in umckalin is a convenient biomarker to distinguish between the two taxa.

Host and yield responses of soybean genotypes resistant or susceptible to Meloidogyne incognita in vivo

Host and yield responses of soybean genotypes resistant to Meloidogyne incognita were verified in semi-field and field trials at four different localities in South Africa. The resistant cultivar LS5995 and susceptible cultivars Prima and Prima2000 were used and each trial consisted of two treatments: fumigated (control) and nematode-infected plots. The number of root-knot nematode eggs and J2 in roots of nematode-infected plants was significantly higher in Prima and Prima2000 compared with those of the resistant genotypes in all trials. Low root and soil nematode population densities were consistently recorded for LS5995 in all trials. Yield of the resistant genotypes did not differ significantly between the fumigated and the nematode-infected plants for all trials, while yields of the susceptible Prima and Prima2000 grown in fumigated plots were significantly higher than those in nematode-infected plots for one microplot as well as one field trial. LS5995 is no longer commercially available in South Africa but is used as a superior source of M. incognita-resistance in breeding programmes for introgression of resistance into high-yielding, locally adapted soybean cultivars.