Wheat stress responses during Russian wheat aphid and Bird Cherry Oat aphid infestation: an analysis of differential protein regulation during plant biotic stress responses
- Louw, Cassandra Alexandrovna
- Authors: Louw, Cassandra Alexandrovna
- Date: 2007
- Subjects: Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3995 , http://hdl.handle.net/10962/d1004055 , Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Description: Plants possess a complex and poorly understood network of defence mechanisms that enable them to counteract the effects of abiotic and biotic stress. Aphid phloem feeding is source of biotic stress in plants. Russian wheat aphid and Bird Cherry-Oat aphid feeding cause significant losses in the annual wheat crop, and control by conventional methods such as pesticide application, has proved to be ineffective. Infestation by the Russian wheat aphid has a particularly devastating effect in South Africa. Aphid-resistant wheat cultivars have been identified but an incomplete understanding of the mechanism of the plant’s resistance thwarts the development of improved cultivars. A two-dimensional gel electrophoresis method was developed, partially optimised and validated in order to determine the effect of Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding on the Betta and Betta DN wheat proteome. Differentially expressed proteins that were up or down regulated more than two fold were identified using PDQuest™ Basic software and matched to known wheat proteins stored in the SwissProt protein database on the basis of their molecular mass and isolectric point. Initial analysis of the differential protein expression of Betta and Betta DN wheat in response to Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding at different growth stages revealed that younger plants display higher levels of resistance than older plants. Feeding by the Bird-Cherry Oat aphid does not result in the upregulation of proteins implicated in a defence response, which indicates that the damage incurred by the plant due to feeding by this aphid is not enough to trigger a classic defence response. Feeding by the more damaging Russian wheat aphid resulted in a stress response in susceptible wheat cultivar Betta, and a defence response in resistant wheat cultivar Betta DN. The infestation of Betta DN resulted in the upregulation of putative thaumatins and amylase trypsin inhibitors, indicating that the Betta DN resistance response could be due to the combined effect of protease inhibitors that discourage aphid phloem feeding and the activation of the salicylic acid and jasmonic acid plant defence pathways.
- Full Text:
- Date Issued: 2007
- Authors: Louw, Cassandra Alexandrovna
- Date: 2007
- Subjects: Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3995 , http://hdl.handle.net/10962/d1004055 , Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Description: Plants possess a complex and poorly understood network of defence mechanisms that enable them to counteract the effects of abiotic and biotic stress. Aphid phloem feeding is source of biotic stress in plants. Russian wheat aphid and Bird Cherry-Oat aphid feeding cause significant losses in the annual wheat crop, and control by conventional methods such as pesticide application, has proved to be ineffective. Infestation by the Russian wheat aphid has a particularly devastating effect in South Africa. Aphid-resistant wheat cultivars have been identified but an incomplete understanding of the mechanism of the plant’s resistance thwarts the development of improved cultivars. A two-dimensional gel electrophoresis method was developed, partially optimised and validated in order to determine the effect of Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding on the Betta and Betta DN wheat proteome. Differentially expressed proteins that were up or down regulated more than two fold were identified using PDQuest™ Basic software and matched to known wheat proteins stored in the SwissProt protein database on the basis of their molecular mass and isolectric point. Initial analysis of the differential protein expression of Betta and Betta DN wheat in response to Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding at different growth stages revealed that younger plants display higher levels of resistance than older plants. Feeding by the Bird-Cherry Oat aphid does not result in the upregulation of proteins implicated in a defence response, which indicates that the damage incurred by the plant due to feeding by this aphid is not enough to trigger a classic defence response. Feeding by the more damaging Russian wheat aphid resulted in a stress response in susceptible wheat cultivar Betta, and a defence response in resistant wheat cultivar Betta DN. The infestation of Betta DN resulted in the upregulation of putative thaumatins and amylase trypsin inhibitors, indicating that the Betta DN resistance response could be due to the combined effect of protease inhibitors that discourage aphid phloem feeding and the activation of the salicylic acid and jasmonic acid plant defence pathways.
- Full Text:
- Date Issued: 2007
Women living with HIV/AIDS: a phenomenological intergenerational interpretation of their experiences
- Chisaka, Janet Kaemba Chishimba
- Authors: Chisaka, Janet Kaemba Chishimba
- Date: 2007
- Subjects: AIDS (Disease) in women -- South Africa -- Case studies HIV positive women -- South Africa -- Case studies Poor women -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3307 , http://hdl.handle.net/10962/d1003095
- Description: This study deals with the impact of HIV/AIDS on women living in chronic poverty. The question arises: Do we focus on their HIV/AIDS stories only or do we include their other lived experiences? This phenomenological study, on two sets of three generations of women infected and affected by HIV/AIDS and living in poverty, is an attempt at understanding the way the women experience their lifeworlds, not only their HIV/AIDS stories. One set includes a grandmother, her daughter who is living with full-blown AIDS, and her granddaughter, while the other includes a grandmother, her daughter and her granddaughter infected with HIV. The initial focus of the study was on the women’s HIV/AIDS narratives. However as the study progressed, especially during the interviews, it became apparent that the women’s generational poverty or chronic poverty was of greater concern to them than the HIV/AIDS that they were experiencing. Of the six participants, only one woman centred her life story on HIV/AIDS. This finding echoes other studies on HIV/AIDS among poor women: that chronic poverty is more threatening to the women than the risk or reality of AIDS. As a phenomenological researcher my aim was to focus on the participants’ own interpretations of the studied phenomenon. However, this was inadequate in accounting for the role that social structures play in shaping and informing the women’s subjective consciousness and experience. For this reason, I used feminist ideas to understand and interpret the women’s patriarchal experiences.
- Full Text:
- Date Issued: 2007
Women living with HIV/AIDS: a phenomenological intergenerational interpretation of their experiences
- Authors: Chisaka, Janet Kaemba Chishimba
- Date: 2007
- Subjects: AIDS (Disease) in women -- South Africa -- Case studies HIV positive women -- South Africa -- Case studies Poor women -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3307 , http://hdl.handle.net/10962/d1003095
- Description: This study deals with the impact of HIV/AIDS on women living in chronic poverty. The question arises: Do we focus on their HIV/AIDS stories only or do we include their other lived experiences? This phenomenological study, on two sets of three generations of women infected and affected by HIV/AIDS and living in poverty, is an attempt at understanding the way the women experience their lifeworlds, not only their HIV/AIDS stories. One set includes a grandmother, her daughter who is living with full-blown AIDS, and her granddaughter, while the other includes a grandmother, her daughter and her granddaughter infected with HIV. The initial focus of the study was on the women’s HIV/AIDS narratives. However as the study progressed, especially during the interviews, it became apparent that the women’s generational poverty or chronic poverty was of greater concern to them than the HIV/AIDS that they were experiencing. Of the six participants, only one woman centred her life story on HIV/AIDS. This finding echoes other studies on HIV/AIDS among poor women: that chronic poverty is more threatening to the women than the risk or reality of AIDS. As a phenomenological researcher my aim was to focus on the participants’ own interpretations of the studied phenomenon. However, this was inadequate in accounting for the role that social structures play in shaping and informing the women’s subjective consciousness and experience. For this reason, I used feminist ideas to understand and interpret the women’s patriarchal experiences.
- Full Text:
- Date Issued: 2007