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Phosphatidic Acid Mediation of Environmentally Induced Adaptive Growth Responses

Han, Eun Hyang
http://rave.ohiolink.edu/etdc/view?acc_num=osu1492678342062212

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Horticulture and Crop Science.
Plant responses to abiotic stresses can be divided into two stages: a rapid perception of the stress and the induction of signaling cascades, followed by longer-term changes in gene expression and, ultimately, adaptive growth. Early stress responses often involve lipid signaling, specifically the production of phosphatidic acid (PA). In this thesis, we present experiments investigating the role of PA in modulating multiple stress responses. Chapter two details the characterization of the role of PA in natural rubber synthesis in guayule (Parthenium argentatum). Natural rubber (NR; cis-1,4-polysisoprene) is produced in rubber particles (RP; specialized organelles surrounded by a monolayer membrane). Our analyses indicated that this membrane contained significant levels of PA, which may function in RP trafficking and/or rubber synthesis. Additionally, we performed a proteomic screen of the proteins localized in the RP membrane and identified approximately 80 proteins, covering 30 functional categories. These proteins will provide targets for both metabolic engineering and breeding strategies designed to increase NR production in the alternative rubber crops Taraxacum kok-saghyz (TK) and guayule. In addition to participating in cold-stress induced rubber synthesis, PA signaling is also involved in salt stress responses, particularly halotropic growth responses. Halotropic growth is defined as directional growth of a plant organ (usually a root) away from an area of increased salt concentration. While the exact mechanisms by which PA impacts halotropism are currently unclear, previous work has provided evidence that PA works in part by modulating auxin transport mechanisms. Chapter three details an investigation into halotropic responses in rice roots. Results show that rice roots exhibit halotropic growth, and that this growth is dependent upon both the production of PA and the action of the protein phosphatase 2A (PP2A) heterotrimeric enzyme complex. Additionally, data indicate that PA-PP2A interactions inhibit PP2A activity in both Arabidopsis and rice, most likely by binding to the PP2A-A regulatory/scaffolding subunit. Data presented in this chapter allow the generation of a model in which salt-stress induced production of PA functions, at least in part, to regulate PP2A activity, modulating halotropic growth responses. In order to better characterize the role of PA-PP2A in modulating stress responses, it is necessary to develop tools to quantify PP2A activity in extracts generated from relatively small tissue samples (i.e., root tips) or in membrane fractions. The two assays which are most commonly used to measure PP2A require relatively large amounts of tissue, and are difficult to conduct in samples containing high levels of lipids or detergent. Chapter 4 presents the development of a new, capillary zonal electrophoresis (CZE) method to quantify PP2A activity in plant and yeast extracts. In addition to using very low amounts of sample, the new method allows the simultaneous quantification of both the phosphorylated and de-phosphorylated forms of a synthetic peptide. As PP2A is involved in regulating not only halotropic growth, but also root tip maintenance, auxin transport, and plant pathogen interactions, the assay presented in chapter 4 has broad spectrum applications in the area of plant biology.
Joshua Blakelsee, Dr. (Advisor)
James Metzger, Dr. (Committee Member)
Katrina Cornish, Dr. (Committee Member)
Matthew Kleinhenz, Dr. (Committee Member)
Feng Qu, Dr. (Committee Member)
327 p.
Agronomy; Biochemistry; Plant Biology; Plant Sciences
Phosphatidic Acid Mediation; Environmentally Induced Adaptive Growth Responses

Recommended Citations

Citations

  • Han, E. H. (2017). Phosphatidic Acid Mediation of Environmentally Induced Adaptive Growth Responses [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492678342062212

    APA Style (7th edition)

  • Han, Eun Hyang. Phosphatidic Acid Mediation of Environmentally Induced Adaptive Growth Responses . 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1492678342062212.

    MLA Style (8th edition)

  • Han, Eun Hyang. "Phosphatidic Acid Mediation of Environmentally Induced Adaptive Growth Responses ." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492678342062212

    Chicago Manual of Style (17th edition)

osu1492678342062212
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This open access ETD is published by The Ohio State University and OhioLINK.