3,3′-diindolylmethane (DIM) belongs to a family of indole glucosinolate compounds that have been ... more 3,3′-diindolylmethane (DIM) belongs to a family of indole glucosinolate compounds that have been shown to improve Brassica napus growth through the modulation of reactive oxygen species when applied exogenously. The B. napus cultivar AV Garnet was previously identified as a vanadium-sensitive cultivar. Therefore, in this study we investigated whether exogenous DIM could improve the vanadium tolerance of AV Garnet. We performed the following experiments: seed germination assessment, dry weight assessment, cell viability assay, chlorophyll content assay, malondialdehyde (MDA) assay, conjugated diene (CD) content assay, hydrogen peroxide (H2O2) content assay, superoxide (O2−) content determination, methylglyoxal (MG) content determination, hydroxyl radical (·OH) concentration determination, ascorbate peroxidase (APX) activity assay, superoxide dismutase (SOD) activity assay, glyoxalase I (Gly I) activity assay, glutathione S-transferase (GST) activity assay and inductively coupled plas...
Keywords Caspase-like activity Cystatins Cysteine proteases Drought Gene expression Glycine max P... more Keywords Caspase-like activity Cystatins Cysteine proteases Drought Gene expression Glycine max Programmed cell death Protein overexpression Reactive oxygen species II ABSTRACT This study investigated the effects that drought stress imposed on the growth and development of soybean plants. Soybeans were initially observed at the whole-plant level in order to identify the physical changes that had taken place in response to drought. Further investigation of the effects of drought stress on Soybean plants were quantified at the molecular level. Physical changes of soybeans in response to drought stress were typified by the change in leaf morphology and pigmentation. At the molecular level, it was observed that drought stress resulted in the accumulation of hydrogen peroxide in soybean leaves, which was met by elevated levels of lipid peroxidation.
The mining of heavy metals from the environment leads to an increase in soil pollution, leading t... more The mining of heavy metals from the environment leads to an increase in soil pollution, leading to the uptake of heavy metals into plant tissue. The build-up of toxic metals in plant cells often leads to cellular damage and senescence. Therefore, it is of utmost importance to produce plants with improved tolerance to heavy metals for food security, as well as to limit heavy metal uptake for improved food safety purposes. To achieve this goal, our understanding of the signaling mechanisms which regulate toxic heavy metal uptake and tolerance in plants requires extensive improvement. In this review, we summarize recent literature and data on heavy metal toxicity (oral reference doses) and the impact of the metals on food safety and food security. Furthermore, we discuss some of the key events (reception, transduction, and response) in the heavy metal signaling cascades in the cell wall, plasma membrane, and cytoplasm. Our future perspectives provide an outlook of the exciting advances...
Medicago truncatula is a forage crop of choice for farmers, and it is a model species for molecul... more Medicago truncatula is a forage crop of choice for farmers, and it is a model species for molecular research. The growth and development and subsequent yields are limited by water availability mainly in arid and semi-arid regions. Our study aims to evaluate the morpho-physiological, biochemical and molecular responses to water deficit stress in four lines (TN6.18, JA17, TN1.11 and A10) of M. truncatula. The results showed that the treatment factor explained the majority of the variation for the measured traits. It appeared that the line A10 was the most sensitive and therefore adversely affected by water deficit stress, which reduced its growth and yield parameters, whereas the tolerant line TN6.18 exhibited the highest root biomass production, a significantly higher increase in its total protein and soluble sugar contents, and lower levels of lipid peroxidation with greater cell membrane integrity. The expression analysis of the DREB1B gene using RT-qPCR revealed a tissue-different...
We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the ... more We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the salt responses of four lines (TN1.11, TN6.18, JA17, and A10) of Medicago truncatula. Results showed that TN1.11 exhibited a high tolerance to salinity, compared with the other lines, recording a salinity induced an increase in soluble sugars and soluble proteins, a slight decrease in malondialdehyde (MDA) accumulation, and less reduction in plant biomass. TN6.18 was the most susceptible to salinity as it showed less plant weight, had elevated levels of MDA, and lower levels of soluble sugars and soluble proteins under salt stress. As transcription factors of the APETALA2/ethylene responsive factor (AP2/ERF) family play important roles in plant growth, development, and responses to biotic and abiotic stresses, we performed a functional characterization of MtERF1 gene. Real-time PCR analysis revealed that MtERF1 is mainly expressed in roots and is inducible by NaCl and low temperature. Add...
Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, whic... more Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, which controls plant responses to stress. This study investigates if changes in ascorbate peroxidase enzymatic activity and glycine betaine content in response to inhibition of nitric oxide synthase-like activity are associated with transcriptional regulation by analyzing transcript levels of genes (betaine aldehyde dehydrogenase) involved in glycine betaine biosynthesis and those encoding antioxidant enzymes (ascorbate peroxidase and catalase) in leaves of maize seedlings treated with an inhibitor of nitric oxide synthase-like activity. In seedlings treated with a nitric oxide synthase inhibitor, transcript levels of betaine aldehyde dehydrogenase were decreased. In plants treated with the nitric oxide synthase inhibitor, the transcript levels of ascorbate peroxidase-encoding genes were down-regulated. We thus conclude that inhibition of nitric oxide synthase-like activity suppresses the ex...
ABSTRACT Please refer to full text to view abstract. Thesis (PhD (Genetics))--University of Stell... more ABSTRACT Please refer to full text to view abstract. Thesis (PhD (Genetics))--University of Stellenbosch, 2011. Includes bibliography.
3,3′-diindolylmethane (DIM) belongs to a family of indole glucosinolate compounds that have been ... more 3,3′-diindolylmethane (DIM) belongs to a family of indole glucosinolate compounds that have been shown to improve Brassica napus growth through the modulation of reactive oxygen species when applied exogenously. The B. napus cultivar AV Garnet was previously identified as a vanadium-sensitive cultivar. Therefore, in this study we investigated whether exogenous DIM could improve the vanadium tolerance of AV Garnet. We performed the following experiments: seed germination assessment, dry weight assessment, cell viability assay, chlorophyll content assay, malondialdehyde (MDA) assay, conjugated diene (CD) content assay, hydrogen peroxide (H2O2) content assay, superoxide (O2−) content determination, methylglyoxal (MG) content determination, hydroxyl radical (·OH) concentration determination, ascorbate peroxidase (APX) activity assay, superoxide dismutase (SOD) activity assay, glyoxalase I (Gly I) activity assay, glutathione S-transferase (GST) activity assay and inductively coupled plas...
Keywords Caspase-like activity Cystatins Cysteine proteases Drought Gene expression Glycine max P... more Keywords Caspase-like activity Cystatins Cysteine proteases Drought Gene expression Glycine max Programmed cell death Protein overexpression Reactive oxygen species II ABSTRACT This study investigated the effects that drought stress imposed on the growth and development of soybean plants. Soybeans were initially observed at the whole-plant level in order to identify the physical changes that had taken place in response to drought. Further investigation of the effects of drought stress on Soybean plants were quantified at the molecular level. Physical changes of soybeans in response to drought stress were typified by the change in leaf morphology and pigmentation. At the molecular level, it was observed that drought stress resulted in the accumulation of hydrogen peroxide in soybean leaves, which was met by elevated levels of lipid peroxidation.
The mining of heavy metals from the environment leads to an increase in soil pollution, leading t... more The mining of heavy metals from the environment leads to an increase in soil pollution, leading to the uptake of heavy metals into plant tissue. The build-up of toxic metals in plant cells often leads to cellular damage and senescence. Therefore, it is of utmost importance to produce plants with improved tolerance to heavy metals for food security, as well as to limit heavy metal uptake for improved food safety purposes. To achieve this goal, our understanding of the signaling mechanisms which regulate toxic heavy metal uptake and tolerance in plants requires extensive improvement. In this review, we summarize recent literature and data on heavy metal toxicity (oral reference doses) and the impact of the metals on food safety and food security. Furthermore, we discuss some of the key events (reception, transduction, and response) in the heavy metal signaling cascades in the cell wall, plasma membrane, and cytoplasm. Our future perspectives provide an outlook of the exciting advances...
Medicago truncatula is a forage crop of choice for farmers, and it is a model species for molecul... more Medicago truncatula is a forage crop of choice for farmers, and it is a model species for molecular research. The growth and development and subsequent yields are limited by water availability mainly in arid and semi-arid regions. Our study aims to evaluate the morpho-physiological, biochemical and molecular responses to water deficit stress in four lines (TN6.18, JA17, TN1.11 and A10) of M. truncatula. The results showed that the treatment factor explained the majority of the variation for the measured traits. It appeared that the line A10 was the most sensitive and therefore adversely affected by water deficit stress, which reduced its growth and yield parameters, whereas the tolerant line TN6.18 exhibited the highest root biomass production, a significantly higher increase in its total protein and soluble sugar contents, and lower levels of lipid peroxidation with greater cell membrane integrity. The expression analysis of the DREB1B gene using RT-qPCR revealed a tissue-different...
We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the ... more We used an integrated morpho-physiological, biochemical, and genetic approach to investigate the salt responses of four lines (TN1.11, TN6.18, JA17, and A10) of Medicago truncatula. Results showed that TN1.11 exhibited a high tolerance to salinity, compared with the other lines, recording a salinity induced an increase in soluble sugars and soluble proteins, a slight decrease in malondialdehyde (MDA) accumulation, and less reduction in plant biomass. TN6.18 was the most susceptible to salinity as it showed less plant weight, had elevated levels of MDA, and lower levels of soluble sugars and soluble proteins under salt stress. As transcription factors of the APETALA2/ethylene responsive factor (AP2/ERF) family play important roles in plant growth, development, and responses to biotic and abiotic stresses, we performed a functional characterization of MtERF1 gene. Real-time PCR analysis revealed that MtERF1 is mainly expressed in roots and is inducible by NaCl and low temperature. Add...
Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, whic... more Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, which controls plant responses to stress. This study investigates if changes in ascorbate peroxidase enzymatic activity and glycine betaine content in response to inhibition of nitric oxide synthase-like activity are associated with transcriptional regulation by analyzing transcript levels of genes (betaine aldehyde dehydrogenase) involved in glycine betaine biosynthesis and those encoding antioxidant enzymes (ascorbate peroxidase and catalase) in leaves of maize seedlings treated with an inhibitor of nitric oxide synthase-like activity. In seedlings treated with a nitric oxide synthase inhibitor, transcript levels of betaine aldehyde dehydrogenase were decreased. In plants treated with the nitric oxide synthase inhibitor, the transcript levels of ascorbate peroxidase-encoding genes were down-regulated. We thus conclude that inhibition of nitric oxide synthase-like activity suppresses the ex...
ABSTRACT Please refer to full text to view abstract. Thesis (PhD (Genetics))--University of Stell... more ABSTRACT Please refer to full text to view abstract. Thesis (PhD (Genetics))--University of Stellenbosch, 2011. Includes bibliography.
Uploads
Papers