Lateral organ boundary formation is highly regulated by transcription factors and hormones such a... more Lateral organ boundary formation is highly regulated by transcription factors and hormones such as auxins and brassinosteroids. However, in contrast to many other developmental processes in plants, no role for signalling peptides in the regulation of this process has been reported yet. The first characterization of the secreted cysteine-rich TAXIMIN (TAX) signalling peptides in Arabidopsis is presented here. TAX1 overexpression resulted in minor alterations in the primary shoot and root metabolome, abnormal fruit morphology, and fusion of the base of cauline leaves to stems forming a decurrent leaf attachment. The phenotypes at the paraclade junction match TAX1 promoter activity in this region and are similar to loss of LATERAL ORGAN FUSION (LOF) transcription factor function. Nevertheless, TAX1 expression was unchanged in lof1lof2 paraclade junctions and, conversely, LOF gene expression was unchanged in TAX1 overexpressing plants, suggesting TAX1 may act independently. This study i...
... Resource access and sustainability concerns are coupled with the rising global trend toward t... more ... Resource access and sustainability concerns are coupled with the rising global trend toward the commercialization of useful plants (Mgbeoji 2006) and as a result medicinal plants ... There was no gender bias among students with regards to knowledge of medicinal plants. ...
Page 1. An improved system for the in vitro regeneration of Thapsia garganica via direct organoge... more Page 1. An improved system for the in vitro regeneration of Thapsia garganica via direct organogenesis – influence of auxins and cytokinins Nokwanda P. Makunga1, Anna K. Ja¨ger1,2 & Johannes van Staden1,* 1Research ...
... 2004. Seeds are collected seasonally from wild populations growing within the Western Cape re... more ... 2004. Seeds are collected seasonally from wild populations growing within the Western Cape region by Rod and Rachel Saunders (http://www. ... In vitro flowering is not unusual (consult Chang and Chang 2003; Vaz et al. 2004; McCartan and van Staden 2003; Taylor et al. ...
Page 1. Abstract Stock cultures of Thapsia garganica grown on Murashige and Skoog agar medium (19... more Page 1. Abstract Stock cultures of Thapsia garganica grown on Murashige and Skoog agar medium (1962) (MS) (0.8% agar [w/v]; pH 5.8) with 0.5 mg l )1 NAA and 1.5 mg l )1 BA were best rooted by sub-jecting to half strength ...
Plant Cell, Tissue and Organ Culture (PCTOC), 2014
ABSTRACT The influence of strigolactones as hormones in plants is not fully characterised even th... more ABSTRACT The influence of strigolactones as hormones in plants is not fully characterised even though they are known to affect plant architecture, both above ground and in the roots. Using an in vitro system, the effects of the synthetic auxins 1-naphthalene acetic acid and indole-3-butyric acid (NAA and IBA) and synthetic strigolactones (GR24 and Nijmegen-1) were tested on microplant development of Sutherlandia frutescens, a leguminous medicinal plant native to South Africa. Considerable phytochemical variation in wild populations has led to the proposal of using micropropagation for this species. This will assist with domestication and provide plants with a more predictable chemistry for the phytopharmaceuticals industry. Nodal explants with an axillary bud were grown on Murashige and Skoog (Plant Physiol 15:473–497, 1962) medium [0.8 % (m/v) agar (pH 5.8), 3 % (m/v) sucrose and 0.1 g/L myo-inositol] supplemented with NAA, IBA, GR24 and Nijmegen-1, either singly or in combination. The amino acid profile and secondary metabolite pool was monitored using LC–MS-profiling. Treatment with NAA promoted mass shoot production, whilst a combination of NAA and Nijmegen-1 also positively influenced the accumulation of amino acids, flavonoids (sutherlandins) and terpenoids (sutherlandiosides) that S. frutescens produces. Since these compounds represent the presumed active compounds in this species and the biomarkers used in quality control assessment of S. frutescens tissues harvested for the pharmaceutical industry, this treatment holds promise for the commercial production of Sutherlandia extracts and herbal medications.
Environmental stresses can significantly alter the synthesis of both primary and secondary metabo... more Environmental stresses can significantly alter the synthesis of both primary and secondary metabolites, resulting in medicinal plants with unpredictable biological activity. Here, in vitro shoot cultures of the medicinal plant Sutherlandia frutescens were used to study the impact of three abiotic stresses (nitrogen availability, drought and salinity), primarily on l-canavanine synthesis. This compound, a non-protein amino acid, is amongst those metabolites linked to the health benefits of Sutherlandia extracts. Nitrogen supplied to microplants positively correlated with canavanine levels, exhibited by a fourfold reduction when nitrates provided were halved. Although the biomass generated was lowered under these conditions, a higher capacity for rooting (52%) in comparison to the controls (37%) became evident. Only a small increase of the canavanine content in microplants growing on 100mM NaCl medium was detected, indicating that salinity stress was not a major limitation on cavanine production, but that it played more of a role in vitro on plantlet morphogenesis. Similarly, PEG as a supplement had little to no effect on canavanine synthesis. We conclude that a deeper understanding of the nutritional requirements for the agricultural crop management of S. frutescens, which serves the herbal products industry, is needed.
Salvia africana-lutea L., an important medicinal sage used in the Western Cape (South Africa), ca... more Salvia africana-lutea L., an important medicinal sage used in the Western Cape (South Africa), can be termed a 'broad-spectrum remedy' suggesting the presence of a multiplicity of bioactive metabolites. This study aimed at assessing wild S. africana-lutea populations for chemotypic variation and anti-Fusarium properties. Samples were collected from four wild growing population sites (Yzerfontein, Silwerstroomstrand, Koeberg and Brackenfell) and one garden growing location in Stellenbosch. Their antifungal activities against Fusarium verticillioides (strains: MRC 826 and MRC 8267) and F. proliferatum (strains: MRC 6908 and MRC 7140) that are aggressive mycotoxigenic phytopathogens were compared using an in vitro microdilution assay. To correlate antifungal activity to chemical profiles, three techniques viz. Gas chromatography-mass spectrometry (GC-MS); Liquid chromatography-mass spectrometry (LC-MS) and 1H Nuclear Magnetic Resonance (NMR) were employed. Principal Component A...
Lateral organ boundary formation is highly regulated by transcription factors and hormones such a... more Lateral organ boundary formation is highly regulated by transcription factors and hormones such as auxins and brassinosteroids. However, in contrast to many other developmental processes in plants, no role for signalling peptides in the regulation of this process has been reported yet. The first characterization of the secreted cysteine-rich TAXIMIN (TAX) signalling peptides in Arabidopsis is presented here. TAX1 overexpression resulted in minor alterations in the primary shoot and root metabolome, abnormal fruit morphology, and fusion of the base of cauline leaves to stems forming a decurrent leaf attachment. The phenotypes at the paraclade junction match TAX1 promoter activity in this region and are similar to loss of LATERAL ORGAN FUSION (LOF) transcription factor function. Nevertheless, TAX1 expression was unchanged in lof1lof2 paraclade junctions and, conversely, LOF gene expression was unchanged in TAX1 overexpressing plants, suggesting TAX1 may act independently. This study i...
... Resource access and sustainability concerns are coupled with the rising global trend toward t... more ... Resource access and sustainability concerns are coupled with the rising global trend toward the commercialization of useful plants (Mgbeoji 2006) and as a result medicinal plants ... There was no gender bias among students with regards to knowledge of medicinal plants. ...
Page 1. An improved system for the in vitro regeneration of Thapsia garganica via direct organoge... more Page 1. An improved system for the in vitro regeneration of Thapsia garganica via direct organogenesis – influence of auxins and cytokinins Nokwanda P. Makunga1, Anna K. Ja¨ger1,2 & Johannes van Staden1,* 1Research ...
... 2004. Seeds are collected seasonally from wild populations growing within the Western Cape re... more ... 2004. Seeds are collected seasonally from wild populations growing within the Western Cape region by Rod and Rachel Saunders (http://www. ... In vitro flowering is not unusual (consult Chang and Chang 2003; Vaz et al. 2004; McCartan and van Staden 2003; Taylor et al. ...
Page 1. Abstract Stock cultures of Thapsia garganica grown on Murashige and Skoog agar medium (19... more Page 1. Abstract Stock cultures of Thapsia garganica grown on Murashige and Skoog agar medium (1962) (MS) (0.8% agar [w/v]; pH 5.8) with 0.5 mg l )1 NAA and 1.5 mg l )1 BA were best rooted by sub-jecting to half strength ...
Plant Cell, Tissue and Organ Culture (PCTOC), 2014
ABSTRACT The influence of strigolactones as hormones in plants is not fully characterised even th... more ABSTRACT The influence of strigolactones as hormones in plants is not fully characterised even though they are known to affect plant architecture, both above ground and in the roots. Using an in vitro system, the effects of the synthetic auxins 1-naphthalene acetic acid and indole-3-butyric acid (NAA and IBA) and synthetic strigolactones (GR24 and Nijmegen-1) were tested on microplant development of Sutherlandia frutescens, a leguminous medicinal plant native to South Africa. Considerable phytochemical variation in wild populations has led to the proposal of using micropropagation for this species. This will assist with domestication and provide plants with a more predictable chemistry for the phytopharmaceuticals industry. Nodal explants with an axillary bud were grown on Murashige and Skoog (Plant Physiol 15:473–497, 1962) medium [0.8 % (m/v) agar (pH 5.8), 3 % (m/v) sucrose and 0.1 g/L myo-inositol] supplemented with NAA, IBA, GR24 and Nijmegen-1, either singly or in combination. The amino acid profile and secondary metabolite pool was monitored using LC–MS-profiling. Treatment with NAA promoted mass shoot production, whilst a combination of NAA and Nijmegen-1 also positively influenced the accumulation of amino acids, flavonoids (sutherlandins) and terpenoids (sutherlandiosides) that S. frutescens produces. Since these compounds represent the presumed active compounds in this species and the biomarkers used in quality control assessment of S. frutescens tissues harvested for the pharmaceutical industry, this treatment holds promise for the commercial production of Sutherlandia extracts and herbal medications.
Environmental stresses can significantly alter the synthesis of both primary and secondary metabo... more Environmental stresses can significantly alter the synthesis of both primary and secondary metabolites, resulting in medicinal plants with unpredictable biological activity. Here, in vitro shoot cultures of the medicinal plant Sutherlandia frutescens were used to study the impact of three abiotic stresses (nitrogen availability, drought and salinity), primarily on l-canavanine synthesis. This compound, a non-protein amino acid, is amongst those metabolites linked to the health benefits of Sutherlandia extracts. Nitrogen supplied to microplants positively correlated with canavanine levels, exhibited by a fourfold reduction when nitrates provided were halved. Although the biomass generated was lowered under these conditions, a higher capacity for rooting (52%) in comparison to the controls (37%) became evident. Only a small increase of the canavanine content in microplants growing on 100mM NaCl medium was detected, indicating that salinity stress was not a major limitation on cavanine production, but that it played more of a role in vitro on plantlet morphogenesis. Similarly, PEG as a supplement had little to no effect on canavanine synthesis. We conclude that a deeper understanding of the nutritional requirements for the agricultural crop management of S. frutescens, which serves the herbal products industry, is needed.
Salvia africana-lutea L., an important medicinal sage used in the Western Cape (South Africa), ca... more Salvia africana-lutea L., an important medicinal sage used in the Western Cape (South Africa), can be termed a 'broad-spectrum remedy' suggesting the presence of a multiplicity of bioactive metabolites. This study aimed at assessing wild S. africana-lutea populations for chemotypic variation and anti-Fusarium properties. Samples were collected from four wild growing population sites (Yzerfontein, Silwerstroomstrand, Koeberg and Brackenfell) and one garden growing location in Stellenbosch. Their antifungal activities against Fusarium verticillioides (strains: MRC 826 and MRC 8267) and F. proliferatum (strains: MRC 6908 and MRC 7140) that are aggressive mycotoxigenic phytopathogens were compared using an in vitro microdilution assay. To correlate antifungal activity to chemical profiles, three techniques viz. Gas chromatography-mass spectrometry (GC-MS); Liquid chromatography-mass spectrometry (LC-MS) and 1H Nuclear Magnetic Resonance (NMR) were employed. Principal Component A...
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