Mohamed S Rafudeen | University of Cape Town (original) (raw)

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Papers by Mohamed S Rafudeen

Research paper thumbnail of Characterisation of the heat stable proteome of the desiccation tolerant form of the resurrection fern Mohria caffrorum

South African Journal of Botany, 2009

Research paper thumbnail of An Overview of the Current Understanding of Desiccation Tolerance in the Vegetative Tissues of Higher Plants

Advances in Botanical Research, 2011

Research paper thumbnail of The use of aeroponics to investigate antioxidant activity in the roots of Xerophyta viscosa

Plant Growth Regulation, 2010

In order to ultimately understand the whole plant mechanism of attaining desiccation tolerance, w... more In order to ultimately understand the whole plant mechanism of attaining desiccation tolerance, we undertook to investigate the root tissues of the resurrection plant Xerophyta viscosa, as previous work has only been conducted on the leaf tissues of resurrection plants. An aeroponic plant growth system was designed and optimised to observe the root’s response to desiccation without the restrictions of a soil medium, allowing easy access to roots. Successful culture of both X.viscosa and the control, Zea mays, was achieved and dehydration stress was implemented through reduction of nutrient solution spraying of the roots. After drying to the air dry state (achieved after 7 days for roots and 10 days for shoots), rehydration was achieved by resumption of root spraying. X.viscosa plants survived desiccation and recovered but Z. mays did not. The activity of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase and quantities of ascorbate and glutathione were determined during root desiccation. There was an initial decline in activity in all enzymes upon drying to 80% RWC, but activity thereafter remained constant, at rates indicative of potential metabolic activity, to the air-dry state. This data suggests that these enzymes are not denatured by desiccation of the root tissue. Ascorbate and glutathione content remained constant at concentrations of 70 and 100 μM, respectively during drying. Thus root tissues appear to retain antioxidant potential during drying, for use in recovery upon rehydration, as has been reported for leaf tissues of this and other resurrection plants.

Research paper thumbnail of Protocols for nuclei isolation and nuclear protein extraction from the resurrection plant Xerophyta viscosa for proteomic studies

Analytical Biochemistry, 2009

deen@uct.ac.za (M.S. Rafudeen). 1 Abbre vi a tions used: HBS, homog e nized NIB super na tant; NI... more deen@uct.ac.za (M.S. Rafudeen). 1 Abbre vi a tions used: HBS, homog e nized NIB super na tant; NIB, nuclear iso la tion buffer; NIBA, NIB buffer con tain ing pro te ase inhib i tor; SDS-PAGE, sodium dodecyl sul fate-poly acryl amide gel elec tro pho re sis; XvPrxII, X. vis co sa per ox ire dox in II enzyme.

Research paper thumbnail of Proteomic analysis of nuclear proteins during dehydration of the resurrection plant Xerophyta viscosa

Plant Growth Regulation, 2010

Xerophyta viscosa (family Velloziaceae) is a monocotyledonous poikilochlorophyllous desiccation t... more Xerophyta viscosa (family Velloziaceae) is a monocotyledonous poikilochlorophyllous desiccation tolerant plant capable of surviving drying its leaf tissue to 5% relative water content (RWC) for prolonged periods and resuming full physiological activity upon rehydration. X. viscosa and other resurrection plants are excellent model systems for the study of desiccation tolerance mechanisms. In this work, the X. viscosa nuclear protein profile was investigated in response to dehydration stress using 2D gel electrophoresis, protein map analysis and mass spectrometry identification. From an average of 438 protein spots detected on the gels, 18 spots were significantly shown to increase in abundance upon dehydration at 35% RWC. Analysis of the 18 dehydration-induced nuclear protein spots resulted in the identification of proteins associated with gene transcription and regulation, cell signalling, molecular chaperone and proteolysis type activities, protein translation, energy metabolism, and novel proteins. This study revealed that X. viscosa nucleus responded to dehydration stress and that desiccation tolerance was controlled by multiple genes within the plant nucleus. This study indicated that adjusting gene regulation and expression of appropriate stress response proteins in the nucleus was sufficient to protect the cellular structures during dehydration and in the dried state.

Research paper thumbnail of Characterisation of the heat stable proteome of the desiccation tolerant form of the resurrection fern Mohria caffrorum

South African Journal of Botany, 2009

Research paper thumbnail of An Overview of the Current Understanding of Desiccation Tolerance in the Vegetative Tissues of Higher Plants

Advances in Botanical Research, 2011

Research paper thumbnail of The use of aeroponics to investigate antioxidant activity in the roots of Xerophyta viscosa

Plant Growth Regulation, 2010

In order to ultimately understand the whole plant mechanism of attaining desiccation tolerance, w... more In order to ultimately understand the whole plant mechanism of attaining desiccation tolerance, we undertook to investigate the root tissues of the resurrection plant Xerophyta viscosa, as previous work has only been conducted on the leaf tissues of resurrection plants. An aeroponic plant growth system was designed and optimised to observe the root’s response to desiccation without the restrictions of a soil medium, allowing easy access to roots. Successful culture of both X.viscosa and the control, Zea mays, was achieved and dehydration stress was implemented through reduction of nutrient solution spraying of the roots. After drying to the air dry state (achieved after 7 days for roots and 10 days for shoots), rehydration was achieved by resumption of root spraying. X.viscosa plants survived desiccation and recovered but Z. mays did not. The activity of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase and quantities of ascorbate and glutathione were determined during root desiccation. There was an initial decline in activity in all enzymes upon drying to 80% RWC, but activity thereafter remained constant, at rates indicative of potential metabolic activity, to the air-dry state. This data suggests that these enzymes are not denatured by desiccation of the root tissue. Ascorbate and glutathione content remained constant at concentrations of 70 and 100 μM, respectively during drying. Thus root tissues appear to retain antioxidant potential during drying, for use in recovery upon rehydration, as has been reported for leaf tissues of this and other resurrection plants.

Research paper thumbnail of Protocols for nuclei isolation and nuclear protein extraction from the resurrection plant Xerophyta viscosa for proteomic studies

Analytical Biochemistry, 2009

deen@uct.ac.za (M.S. Rafudeen). 1 Abbre vi a tions used: HBS, homog e nized NIB super na tant; NI... more deen@uct.ac.za (M.S. Rafudeen). 1 Abbre vi a tions used: HBS, homog e nized NIB super na tant; NIB, nuclear iso la tion buffer; NIBA, NIB buffer con tain ing pro te ase inhib i tor; SDS-PAGE, sodium dodecyl sul fate-poly acryl amide gel elec tro pho re sis; XvPrxII, X. vis co sa per ox ire dox in II enzyme.

Research paper thumbnail of Proteomic analysis of nuclear proteins during dehydration of the resurrection plant Xerophyta viscosa

Plant Growth Regulation, 2010

Xerophyta viscosa (family Velloziaceae) is a monocotyledonous poikilochlorophyllous desiccation t... more Xerophyta viscosa (family Velloziaceae) is a monocotyledonous poikilochlorophyllous desiccation tolerant plant capable of surviving drying its leaf tissue to 5% relative water content (RWC) for prolonged periods and resuming full physiological activity upon rehydration. X. viscosa and other resurrection plants are excellent model systems for the study of desiccation tolerance mechanisms. In this work, the X. viscosa nuclear protein profile was investigated in response to dehydration stress using 2D gel electrophoresis, protein map analysis and mass spectrometry identification. From an average of 438 protein spots detected on the gels, 18 spots were significantly shown to increase in abundance upon dehydration at 35% RWC. Analysis of the 18 dehydration-induced nuclear protein spots resulted in the identification of proteins associated with gene transcription and regulation, cell signalling, molecular chaperone and proteolysis type activities, protein translation, energy metabolism, and novel proteins. This study revealed that X. viscosa nucleus responded to dehydration stress and that desiccation tolerance was controlled by multiple genes within the plant nucleus. This study indicated that adjusting gene regulation and expression of appropriate stress response proteins in the nucleus was sufficient to protect the cellular structures during dehydration and in the dried state.