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Alfred Botha – One of the best experts on this subject based on the ideXlab platform.

  • Micro-particle-induced X-ray emission mapping of elemental distribution in roots of a Mediterranean-type sclerophyll, Agathosma betulina (Berg.) Pillans, colonized by Cryptococcus laurentii.
    Plant Cell & Environment, 2010
    Co-Authors: K. J. Cloete, Alex J. Valentine, Wojciech J. Przybyłowicz, Jolanta Mesjasz-przybyłowicz, Alban D. Barnabas, Alfred Botha

    Abstract:

    The role of rhizosphere yeasts as plant nutrient-scavenging microsymbionts in resource-limited Mediterranean-type heathlands is unknown. This study, therefore, focused on quantitative elemental distribution within the roots of a medicinal sclerophyll, Agathosma betulina (Berg.) Pillans, grown under nutrient-poor conditions, and colonized by Cryptococcus laurentii. Micro-particle-induced X-ray emission (PIXE) was used to assess quantitative elemental distribution within the roots of A. betulina inoculated with viable C. laurentii, as well as within roots of control plants that received autoclaved yeast. To aid in the interpretation of heterogeneous elemental distribution patterns, apoplastic barriers (Casparian bands) in root tissues were located using fluorescence microscopy. In addition, root cross-sections were examined for endophytic C. laurentii using light and transmission electron microscopy (TEM). The average concentrations of P, Fe and Mn were significantly (P < 0.05) higher in roots of yeast-inoculated plants, compared to control plants. Casparian bands were observed in the exodermal cells of both treatments, and the presence of these bands was correlated with elemental enrichment in the epi/exodermal-outer cortical tissues. Light and TEM micrographs revealed that the yeast was not a root endophyte. This is the first report describing the role of a soil yeast as a plant nutrient-scavenging microsymbiont.

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  • Evidence of Symbiosis Between the Soil Yeast Cryptococcus laurentii and a Sclerophyllous Medicinal Shrub, Agathosma betulina (Berg.) Pillans
    Microbial Ecology, 2009
    Co-Authors: K. J. Cloete, A. J. Valentine, Marietjie A. Stander, Louisa M. Blomerus, Alfred Botha

    Abstract:

    The interaction between a common soil yeast, Cryptococcus laurentii , and a slow-growing medicinal plant adapted to low-nutrient soils, Agathosma betulina (Berg.) Pillans, was studied. C. laurentii CAB 578 was isolated from the rhizosphere of wild A. betulina , and liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis revealed that the yeast was capable of producing polyamines, such as cadaverine and spermine, while growing in vitro in a chemically defined medium. Since the exogenous application of polyamines are known to impact on root growth, these findings supported the results obtained when axenic cultures of A. betulina seedlings were inoculated with C. laurentii CAB 578 and cultivated for 5 months under glasshouse conditions. The presence of the yeast increased root growth by 51%. Using soil dilution plates, it was demonstrated that yeast numbers were greater in the vicinity of the roots than in the bulk soil. In addition, fluoromicroscopy, in combination with the fluorescent probes Fungo light and Calcofluor white, revealed the presence of metabolic active yeast colonies on the rhizoplane 5 months after initiation of the experimentation. The study provided evidence for a symbiosis between C. laurentii and A. betulina .

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  • Nutritional effects of indigenous arbuscular mycorrhizal associations on the sclerophyllous species Agathosma betulina
    Web Ecology, 2007
    Co-Authors: Karen Jacqueline Cloete, Alex J. Valentine, L. M. Blomerus, Alfred Botha, María A. Pérez-fernández

    Abstract:

    Relatively little is currently known about the seedling physiology of arbuscular mycorrhizal (AM) Agathosma betulina , a sclerophyllous crop plant cultivated for its high-value essential oils and food additives. In addition, virtually nothing is known about the AM associations of this plant. Consequently, the effect of an indigenous community of AM fungi on P nutrition and C economy in seedlings, grown in nursery conditions, was determined during different stages of host and AM fungal establishment. AM fungal ribosomal gene sequence analyses were used to identify some of the fungi within the roots, responsible for the nutritional changes. During the early stages of host and AM fungal establishment (0 to 77 days after germination), host growth was reduced, whereas the rate of P-uptake and growth respiration was increased. Beyond 77 days of growth, the rate of P-uptake and growth respiration declined. These findings, together with results obtained after molecular analyses of root associated fungal DNA, indicate that AM fungi belonging to the genera Acaulospora and Glomus , improve P-uptake and costs of utilization during the early stages of seedling establishment in a nutrient-poor soil.

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Alvaro Viljoen – One of the best experts on this subject based on the ideXlab platform.

  • Hyperspectral Imaging as a Rapid Quality Control Method for Herbal Tea Blends
    MDPI AG, 2017
    Co-Authors: Majolie Djokam, Alvaro Viljoen, Maxleene Sandasi, Weiyang Chen, Ilze Vermaak

    Abstract:

    In South Africa, indigenous herbal teas are enjoyed due to their distinct taste and aroma. The acclaimed health benefits of herbal teas include the management of chronic diseases such as hypertension and diabetes. Quality control of herbal teas has become important due to the availability of different brands of varying quality and the production of tea blends. The potential of hyperspectral imaging as a rapid quality control method for herbal tea blends from rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia), buchu (Agathosma Betulina) and cancerbush (Sutherlandia frutescens) was investigated. Hyperspectral images of raw materials and intact tea bags were acquired using a sisuChema shortwave infrared (SWIR) hyperspectral pushbroom imaging system (920–2514 nm). Principal component analysis (PCA) plots showed clear discrimination between raw materials. Partial least squares discriminant analysis (PLS-DA) models correctly predicted the raw material constituents of each blend and accurately determined the relative proportions. The results were corroborated independently using ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). This study demonstrated the application of hyperspectral imaging coupled with chemometric modelling as a reliable, rapid and non-destructive quality control method for authenticating herbal tea blends and to determine relative proportions in a tea bag

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  • Adulteration in commercial buchu dietary supplements: Analyses of commercial and authentic buchu samples and comparative studies of Agathosma betulina and Agathosma crenulata by microscopy and HPTLC
    South African Journal of Botany, 2015
    Co-Authors: Vijayasankar Raman, Alvaro Viljoen, S Sagi, Ahmed M. Galal, Bharathi Avula, Ikhlas A. Khan

    Abstract:

    Buchu is a popular medicinal plant known for its beneficial properties such as diuretic, urinary tract antiseptic, stimulant and tonic. It has traditionally been used to treat urinary tract infections and stomach troubles. It is widely marketed in the USA in various forms as dietary supplements. Buchu used in commerce is mainly derived from Agathosma betulina known as round-leaf or short buchu. However, leaves of Agathosma crenulata, which may contain high levels of pulegone in the essential oil, and other closely related species are often marketed as or used to adulterate buchu thus making the product potentially unsafe for human consumption. In the present work, 43 samples of authentic and commercial buchu were assessed by microscopy and high performance thin layer chromatography methods. Adulterations or contaminations with senna, grass and various other extraneous materials were observed in some of the buchu products. HPTLC fingerprinting showed that the profiles of 11 samples were not comparable to those of authentic and botanically verified buchu samples. Detailed morphology and anatomy of the leaves of A. betulina and A. crenulata by light and scanning electron microscopy are illustrated and discussed. Minute prismatic crystals of calcium oxalate were observed for the first time in A. betulina.

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  • differentiating between Agathosma betulina and Agathosma crenulata a quality control perspective
    Journal of Applied Research on Medicinal and Aromatic Plants, 2014
    Co-Authors: Thandazile Mavimbela, Alvaro Viljoen, Ilze Vermaak

    Abstract:

    Agathosma betulina (Bergius) Pillans and Agathosma crenulata (L.) Pillans, ‘buchu’, have been used traditionally as an antispasmodic, antipyretic, cough remedy, diuretic and in the treatment of urinary tract infections. The two species are usually differentiated on the basis of their leaf shape as A. betulina has round leaves while A. crenulata has long oval leaves. This authentication method based on morphology has proven to be inadequate because of variable morphotypes. In this study, 63 leaf samples of A. betulina and A. crenulata were used to develop phytochemical fingerprints using high performance thin layer chromatography (HPTLC), liquid chromatography coupled to mass spectroscopy (LC–MS), near infrared spectroscopy (NIR) and mid infrared spectroscopy (MIR). The data were processed using Markerlynx® and SIMCA-P+® chemometric analysis software. Orthogonal projections to latent structure dicriminant analysis (OPLS-DA) revealed separation into two distinct clusters based on all the analytical methods investigated, one containing A. betulina samples and the other A. crenulata samples. Using HPTLC a visible difference between the species was determined to be the presence of a blue band at Rf 0.65 in A. crenulata only while LC–MS indicated the presence of quercetin-dimethyl ether-glucoside in A. betulina only. The vibrational spectroscopy results showed quantitative differences as the two species had similar peaks but with different intensities. The results showed that any of these methods can be used to distinguish between the two species.

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K. J. Cloete – One of the best experts on this subject based on the ideXlab platform.

  • Effect of the soil yeast Cryptococcus laurentii on the photosynthetic water and nutrient-use efficiency and respiratory carbon costs of a Mediterranean sclerophyll, Agathosma betulina (Berg.) Pillans
    Symbiosis, 2010
    Co-Authors: K. J. Cloete, A. J. Valentine, A. Botha

    Abstract:

    Nothing is known about the effect of soil yeasts on the photosynthetic resource-use and carbon dynamics of plants. Here, we determined the effect of a plant growth-promoting isolate of Cryptococcus laurentii on the photosynthetic water and nutrient-use efficiencies, as well as the carbon economy of a Mediterranean sclerophyll, Agathosma betulina , grown under axenic conditions. The data showed that the higher photosynthetic water-use efficiency in yeast-inoculated plants was a consequence of higher maximum rates of CO_2 assimilation, which was not related to foliar N and P content. We propose that photosynthetic stimulation in yeast-inoculated plants was a result of the increased demand for photosynthates of the yeast-root symbiosis.

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  • Micro-particle-induced X-ray emission mapping of elemental distribution in roots of a Mediterranean-type sclerophyll, Agathosma betulina (Berg.) Pillans, colonized by Cryptococcus laurentii.
    Plant Cell & Environment, 2010
    Co-Authors: K. J. Cloete, Alex J. Valentine, Wojciech J. Przybyłowicz, Jolanta Mesjasz-przybyłowicz, Alban D. Barnabas, Alfred Botha

    Abstract:

    The role of rhizosphere yeasts as plant nutrient-scavenging microsymbionts in resource-limited Mediterranean-type heathlands is unknown. This study, therefore, focused on quantitative elemental distribution within the roots of a medicinal sclerophyll, Agathosma betulina (Berg.) Pillans, grown under nutrient-poor conditions, and colonized by Cryptococcus laurentii. Micro-particle-induced X-ray emission (PIXE) was used to assess quantitative elemental distribution within the roots of A. betulina inoculated with viable C. laurentii, as well as within roots of control plants that received autoclaved yeast. To aid in the interpretation of heterogeneous elemental distribution patterns, apoplastic barriers (Casparian bands) in root tissues were located using fluorescence microscopy. In addition, root cross-sections were examined for endophytic C. laurentii using light and transmission electron microscopy (TEM). The average concentrations of P, Fe and Mn were significantly (P < 0.05) higher in roots of yeast-inoculated plants, compared to control plants. Casparian bands were observed in the exodermal cells of both treatments, and the presence of these bands was correlated with elemental enrichment in the epi/exodermal-outer cortical tissues. Light and TEM micrographs revealed that the yeast was not a root endophyte. This is the first report describing the role of a soil yeast as a plant nutrient-scavenging microsymbiont.

    Free Register to Access Article

  • Evidence of Symbiosis Between the Soil Yeast Cryptococcus laurentii and a Sclerophyllous Medicinal Shrub, Agathosma betulina (Berg.) Pillans
    Microbial Ecology, 2009
    Co-Authors: K. J. Cloete, A. J. Valentine, Marietjie A. Stander, Louisa M. Blomerus, Alfred Botha

    Abstract:

    The interaction between a common soil yeast, Cryptococcus laurentii , and a slow-growing medicinal plant adapted to low-nutrient soils, Agathosma betulina (Berg.) Pillans, was studied. C. laurentii CAB 578 was isolated from the rhizosphere of wild A. betulina , and liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis revealed that the yeast was capable of producing polyamines, such as cadaverine and spermine, while growing in vitro in a chemically defined medium. Since the exogenous application of polyamines are known to impact on root growth, these findings supported the results obtained when axenic cultures of A. betulina seedlings were inoculated with C. laurentii CAB 578 and cultivated for 5 months under glasshouse conditions. The presence of the yeast increased root growth by 51%. Using soil dilution plates, it was demonstrated that yeast numbers were greater in the vicinity of the roots than in the bulk soil. In addition, fluoromicroscopy, in combination with the fluorescent probes Fungo light and Calcofluor white, revealed the presence of metabolic active yeast colonies on the rhizoplane 5 months after initiation of the experimentation. The study provided evidence for a symbiosis between C. laurentii and A. betulina .

    Free Register to Access Article