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Alfred Botha - One of the best experts on this subject based on the ideXlab platform.
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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, 2010Co-Authors: K. J. Cloete, Alex J. Valentine, Wojciech J. Przybyłowicz, Jolanta Mesjasz-przybyłowicz, Alban D. Barnabas, Alfred BothaAbstract: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, 2009Co-Authors: K. J. Cloete, A. J. Valentine, Marietjie A. Stander, Louisa M. Blomerus, Alfred BothaAbstract: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, 2007Co-Authors: Karen Jacqueline Cloete, Alex J. Valentine, L. M. Blomerus, Alfred Botha, María A. Pérez-fernándezAbstract: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.
Alvaro Viljoen - One of the best experts on this subject based on the ideXlab platform.
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Hyperspectral Imaging as a Rapid Quality Control Method for Herbal Tea Blends
MDPI AG, 2017Co-Authors: Majolie Djokam, Alvaro Viljoen, Maxleene Sandasi, Weiyang Chen, Ilze VermaakAbstract: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, 2015Co-Authors: Vijayasankar Raman, Alvaro Viljoen, S Sagi, Ahmed M. Galal, Bharathi Avula, Ikhlas A. KhanAbstract: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, 2014Co-Authors: Thandazile Mavimbela, Alvaro Viljoen, Ilze VermaakAbstract: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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Differentiating between Agathosma betulina and Agathosma crenulata – A quality control perspective
Journal of Applied Research on Medicinal and Aromatic Plants, 2014Co-Authors: Thandazile Mavimbela, Alvaro Viljoen, Ilze VermaakAbstract: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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COULD VIBRATIONAL SPECTROSCOPY REVOLUTIONISE QUALITY CONTROL OF HERBAL MEDICINES
Reviews on Clinical Pharmacology and Drug Therapy, 2012Co-Authors: Alvaro Viljoen, Ilze Vermaak, Viljoen Alvaro, Vermaak IlzeAbstract:s. PHYTOPHARM 2012 M 114 Obzory po kliniceskoj farmacologii i lekarstvennoj terapii [Reviews of clinical pharmacology and drug therapy] ТОМ 10/2012/2 COULD VIBRATIONAL SPECTROSCOPY REVOLUTIONISE QUALITY CONTROL OF HERBAL MEDICINES? © Viljoen Alvaro, Vermaak Ilze Department of Pharmaceutical Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa Vibrational spectroscopy includes near infrared (NiR) mid-infrared (MiR) and Raman spectroscopy. These methods in combination with multivariate data analysis have proved to be powerful analytical techniques and have been implemented in various industries such as the petrochemical, agricultural and food industries. The quality of herbal medicines is of great concern as many consumers now choose herbal medicines over Western medicines and cases of mistaken identity (substitutions) or adulteration with other species with sometimes dire health consequences or loss of consumer trust in the product due to ineffectiveness has been reported. The quality of herbal medicines is assessed both qualitatively (authentication) and quantitatively through the quantification of specific biomarkers. Traditional analytical methods used to determine quality such as high performance liquid chromatography and mass spectrometry are destructive, expensive and time-consuming. Vibrational spectroscopy methods have major advantages over these methods in that it is simple, rapid, relatively cheap and non-destructive. Various examples of quality control methods developed using vibrational spectroscopy techniques will be described for medicinally and commercially important plant species: to discriminate between closely related plant species (e. g. Agathosma betulina and A. crenulata; Pelargonium reniforme and P. sidoides), a case of mistaken identity (Eriocephalus punctulatus and E. tenuifolius) and as a quantification tool for biomarkers (e. g. pulegone, diosphenol, isomenthone etc. in A. betulina essential oils). hyperspectral imaging uses the platform of vibrational spectroscopy and multivariate data analysis but adds an extra data dimension opening up a range of novel applications in the quality control of herbal medicines such as authentication using whole dried fruits (e. g. Illicium anisatum and I. verum). from these examples it is evident, the revolution has already begun. THE METABOLISM OF LIGNANS FROM FRUCTUS SCHISANDRA © Yin Jun , Cao Yun-Feng , Yang Ling 2 School of Traditional Chinese Medicines, Shenyang Pharmaceutical University, Shenyang 110016, China Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China After metabolites from dibenzocyclooctadiene lignans (Schizandrin, deoxyschizandrin and schisantherin A) of Schisandra chinensis incubated with human liver microsomes were isolated by hPlC and their structures were identified by lC–MS, h-NMR and C-NMR, the study combined correlation analysis, chemical inhibition studies, assays with recombinant CyPs and enzyme kinetics indicated that CyP3A4 was the main hepatic isoform. Three metabolites were isolated by hPlC and their structures were identified to be 8 (R)-hydroxylschizandrin, 2-demethyl-8 (R)-hydroxyl-schizandrin, 3-demethyl-8 (R)-hydroxyl-schizandrin, Rat and minipig liver microsomes were applied to evaluate species differences, and the results showed little difference among the mentioned species. Speculated that deoxyschizandrin might undergo hydroxylation in hlMs, and schizandrin could represent the corresponding metabolite. The data also show that deoxyschizandrin metabolism to form schizandrin specially mediated by CyP3A4, is the principal route of disposition in humans. The specificity, high affinity, and high turnover make deoxyschizandrin hydroxylation an excellent probe drug for CyP3A4 activity in vitro. The metabolic pathway of schisantherin A validated the inhibitory mechanism against CyP3A4 undergoes demethylenenation in the human liver microsomes. iC 50 drift and dynamics test indicate that schisantherin A is inhibitor which shows dependency to NAdP and time, which illustrates that the methylene of schisantherin A produced active intermediate during the catalyzed reaction, thereby presents forceful inhibitory effect against CyP3A4. The lignans containing methylenedioxy abundant in fructus Schisandra probably reduce clinical value thereof. in mice liver microsomes, schisantherin A, schizandrol b and schizandrin b showed strong inhibition against metablism schizandrin and deoxschizandrin. Our research results indicate that why deoxyschizandrin presented forceful anti-multidrug resistance in vitro but reduced or vanished in vivo, and the extract of fructus Schisandra containing deoxyschizandrin presents forceful anti-multidrug resistance in vivo.
K. J. Cloete - One of the best experts on this subject based on the ideXlab platform.
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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, 2010Co-Authors: K. J. Cloete, A. J. Valentine, A. BothaAbstract: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, 2010Co-Authors: K. J. Cloete, Alex J. Valentine, Wojciech J. Przybyłowicz, Jolanta Mesjasz-przybyłowicz, Alban D. Barnabas, Alfred BothaAbstract: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, 2009Co-Authors: K. J. Cloete, A. J. Valentine, Marietjie A. Stander, Louisa M. Blomerus, Alfred BothaAbstract: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 .
Aneesa Moolla - One of the best experts on this subject based on the ideXlab platform.
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Indigenous South African Medicinal Plants - Part 5: Agathosma betulina (‘buchu’)
SA Pharmaceutical Journal, 2007Co-Authors: Alvaro Viljoen, Aneesa MoollaAbstract:The genus Agathosma (Rutaceae) consists of approximately 150 species indigenous to South Africa. These aromatic shrubs that are typical of the fynbos vegetation are found in most habitats throughout the Cape Floral Kingdom. Agathosma betulina (‘round-leaf buchu’) is characterised by a smaller, round leaf with a recurved apex whereas Agathosma crenulata (‘oval-leaf buchu’) is characterised by a larger, oval-shaped leaf without the recurved apex. A. betulina is a resprouting, broad-leaved, fragrant shrub that grows to a height of two meters.
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Biological activity and toxicity profile of 17 Agathosma (Rutaceae) species
South African Journal of Botany, 2007Co-Authors: Aneesa Moolla, S F Van Vuuren, Alvaro ViljoenAbstract:Abstract The antimicrobial, anti-oxidant and cytotoxic activities of the extracts obtained from 17 indigenous Agathosma species (19 samples) were investigated in order to validate the historic and continued use of Agathosma species in traditional healing. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) method on four pathogens, i.e. Staphylococcus aureus (ATCC 12600), Bacillus cereus (ATCC 11778), Klebsiella pneumoniae (NCTC 9633) and Candida albicans (ATCC 10231). The anti-oxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, while the cytotoxic properties was determined using the MTT (3-[4,5-dimethyl-2-thiazol-yl]-2,5-diphenyl-2H-tetrazolium bromide) cellular viability assay. Agathosma ovata (round-leaf) displayed the best activity against S. aureus and B. cereus with MIC values of 0.16 mg/ml and 0.13 mg/ml, respectively. Most of the extracts had moderate to poor activity in the DPPH assay with the exception of A. capensis (Gamka) and A. pubigera which were the two most active species in the assay (IC50 values of 24.08 ± 4.42 μg/ml and 35.61 ± 0.86 μg/ml). The results obtained from the ABTS assay differed from that of the DPPH assay. All extracts showed greater activity in the ABTS assay with A. namaquensis and A. capensis (Besemfontein) being the most active species (IC50 values of 15.66 ± 4.57 μg/ml and 19.84 ± 0.09 μg/ml). Agathosma lanata (IC50 value of 26.17 ± 9.58 μg/ml) and A. ovata (round-leaf) (IC50 value of 25.20 ± 6.30 μg/ml) proved to be the most toxic in the MTT assay. Agathosma arida, A. collina, A. hirsuta, A. pubigera, A. roodebergensis, A. stipitata and A. zwartbergense also displayed some degree of toxicity.
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Indigenous South African medicinal plants : Part 5 : Agathosma betulina ('buchu') : medicinal plants
SA Pharmaceutical Journal, 2007Co-Authors: Alvaro Viljoen, Aneesa MoollaAbstract:The genus Agathosma (Rutaceae) consists of approximately 150 species indigenous to South Africa. These aromatic shrubs that are typical of the fynbos vegetation are found in most habitats throughout the Cape Floral Kingdom. Agathosma betulina ('round-leaf buchu') is characterised by a smaller, round leaf with a recurved apex whereas Agathosma crenulata ('oval-leaf buchu') is characterised by a larger, oval-shaped leaf without the recurved apex.
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di o s u fric n M ic n l nts In gen u So th a e i a l Indigenous South African Medicinal Plants
2007Co-Authors: Aneesa MoollaAbstract:.Agathosma betulina (‘round-leaf buchu’) is characterised by a smaller, round leaf with a recurved apex whereas Agathosma crenulata (‘oval-leaf buchu’) is characterised by a larger, oval-shaped leaf without the recurved apex 2 . A. betulina is a resprouting, broad-leaved, fragrant shrub that grows to a height of two meters. The leaves are of a pale green colour, 20 mm long, leathery and glossy, with a blunt, strongly curved tip and a finely toothed margin. Conspicuous round oil glands are scattered throughout the leaf (along the margins and lower surfaces). The leaves are less than twice as long as broad. They are strongly aromatic and the oil is golden in colour, with a strong-sweetish, peppermintlike odour. The flowers are large, star-shaped, five petalled, usually solitary, axillary, and white to purplish pink in color. The brownish fruits are five chambered. The plant is particularly adapted to dry conditions and can be found on sunny hillsides where other crops will not succeed. It can be found on the rocky sandstone slopes of the north western Cape region (Bokkeveld to Grootwinterhoek Mountains) 3 .
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Indigenous South African Medicinal Plants Indigenous South African Medicinal Plants Indigenous South African Medicinal Plants Indigenous South African Medicinal Plants Indigenous South African Medicinal Plants
2007Co-Authors: Aneesa MoollaAbstract:.Agathosma betulina (‘round-leaf buchu’) is characterised by a smaller, round leaf with a recurved apex whereas Agathosma crenulata (‘oval-leaf buchu’) is characterised by a larger, oval-shaped leaf without the recurved apex 2 . A. betulina is a resprouting, broad-leaved, fragrant shrub that grows to a height of two meters. The leaves are of a pale green colour, 20 mm long, leathery and glossy, with a blunt, strongly curved tip and a finely toothed margin. Conspicuous round oil glands are scattered throughout the leaf (along the margins and lower surfaces). The leaves are less than twice as long as broad. They are strongly aromatic and the oil is golden in colour, with a strong-sweetish, peppermintlike odour. The flowers are large, star-shaped, five petalled, usually solitary, axillary, and white to purplish pink in color. The brownish fruits are five chambered. The plant is particularly adapted to dry conditions and can be found on sunny hillsides where other crops will not succeed. It can be found on the rocky sandstone slopes of the north western Cape region (Bokkeveld to Grootwinterhoek Mountains) 3 .
A. J. Valentine - One of the best experts on this subject based on the ideXlab platform.
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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, 2010Co-Authors: K. J. Cloete, A. J. Valentine, A. BothaAbstract: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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Evidence of Symbiosis Between the Soil Yeast Cryptococcus laurentii and a Sclerophyllous Medicinal Shrub, Agathosma betulina (Berg.) Pillans
Microbial Ecology, 2009Co-Authors: K. J. Cloete, A. J. Valentine, Marietjie A. Stander, Louisa M. Blomerus, Alfred BothaAbstract: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 .
