<p> Manipulating the phenylpropanoid (Pp) pathway has been of great focus to bio-engineers as this pathway is responsible for production of many compounds that are important to human health for their known antioxidant, anti-viral, anti-inflammatory, anti-allergenic and vasodilatory properties. The secondary by products of the Pp pathway are important for the physiological well-being of the plant as it contributes to plant’s ability to tolerate changing environment. Plant bio-engineering, involves manipulating gene expression of proteins that regulate functional proteins which are known to attribute to stress tolerance. Our research focused on one such regulatory protein called the 14-3-3 lambda (14-3-3λ) protein and its effects on anthocyanin production in two different plants: a plant model <i>Arabidopsis thaliana </i> (<i>A. thaliana, Columbia-0</i>), and a naturally drought tolerant resurrection plant <i>Selaginella lepidophylla</i> (<i> S. lepi</i>). Due to their structural characteristics the family of 14-3- 3 proteins bind to many different client proteins and hence can function as signaling factors in eukaryotes. Anthocyanins are anti-oxidants produced in plants that alter plants physiology to resist stress. The goal of this study was to establish which nodes in the anthocyanin synthesis pathways are influenced by 14-3-3λ in both <i>A. thaliana</i> and <i>S. lepi </i>. Data from this study established the steps in the Anthocyanin pathway that 14-3-3λ affects to alter anthocyanin production during normal hydration and drought stress states. Based on our published studies and experimental data we have identified that the 14-3-3λ isoform is playing a significant role in the anthocyanin pathway during drought stress. Using a reverse genetics approach, the amounts of secondary anthocyanin metabolites produced in a 14-3-3λ knockout mutant were compared to the wild-type <i> A. thaliana</i> during normal hydration and drought conditions. Analytical techniques such as high performance liquid chromatography (HPLC) and liquid chromatography-Mass Spectrometry (LC-MS/MS) in combination with open access databases were used for metabolite profiling. The metabolite profile lead to candidate metabolites that differed between the drought-treated and hydrated groups in the knockout mutants and wild-type. Identification of these metabolites determined the nodes of Pp pathway that were affected by 14-3-3λ, namely the enzymes chalcone synthase and chalcone isomerase. These findings in <i> A. thaliana</i> were expanded in the naturally drought resistant plant <i> S. lepi</i> using similar analytical approaches employed in <i> A. thaliana</i>. The results proved that 14-3-3λ affects biosynthesis of anthocyanin during drought stress in <i>A. thaliana</i> and <i> S. lepi</i> in a similar manner, hence suggesting a similar role of 14-3-3λ in the production of anthocyanins in both the plants.</p><p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10631482 |
| Date | 22 July 2017 |
| Creators | Nabbie, Fizal N. |
| Publisher | University of the Sciences in Philadelphia |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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