Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Stanley J. Roux. Vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Restricted as requested by author. Restricted access for 1 year 2007-03-31. Also available online.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 140-154).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 112-128). Also available on the World Wide Web.

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Doctor of Philosophy / Biochemistry and Molecular Biophysics Interdepartmental Program / Timothy Durrett / In plants including the members of Brassicaceae family, such as Arabidopsis thaliana and Brassica juncea, seed storage reserves, which include lipids and proteins, accumulate in seeds during development. Triacylglycerols (TAG) are the major storage lipids found in the developing seeds, petals, pollen grains, and fruits of plants. In Arabidopsis seeds, acyl-CoA: diacylglycerol acyltransferase 1 (DGAT1) is the major enzyme contributing to TAG biosynthesis. In Arabidopsis, dgat1-1 mutants retain 60-80% seed TAG content due to the involvement of phospholipid: diacylglycerol acyltransferase (PDAT1) in acyl-CoA independent TAG biosynthesis. My study focuses on the elucidation and functional characterization of novel genes involved in the regulation of the TAG biosynthesis pathway. In developing seeds of the dgat1-1 mutant, altered fatty acid composition was observed with reduced TAG content and increased polar lipid content as compared to wild type. RNA-Seq of developing Arabidopsis seeds was employed to detect differentially expressed genes in dgat1-1. An empirical analysis for differential gene expression revealed a significant number of differentially expressed genes among all developmental stages in dgat1-1. Significant changes in gene expression profile were detected in lipid-related genes such as lipases and desaturases. RT-PCR was used to confirm the differential expression of major lipid-related genes including DGAT1, PDAT, and FAD2. Lipid profiling of T-DNA insertion mutants for differentially expressed genes revealed significant changes in lipid content and composition. Mutations in a member of the α, β-hydrolase family, encoded by gene named PLIP1, resulted in smaller seed and an altered seed oil phenotype. Also, combining the dgat1-1 and plip1-2 mutations resulted in a lethal phenotype, demonstrating the important role of this enzyme in embryo development and TAG biosynthesis. To identify key components in the regulation of storage lipid biosynthesis, correlation analysis using differential transcript abundance and lipid profile during different stages of seed development from dgat1-1 and wild type lines of Arabidopsis was performed. Using clustering analysis with Pearson correlation coefficient and single linkage identified one cluster of genes which included PLIP1, FAD2, FAD3, and PDCT . Similar analysis using combined data from the neutral and polar fractions resulted in clustering of lipids containing polyunsaturated fatty acids. To investigate the reduced seed germination phenotype for mature seeds of dgat1-1 and non-germinating green seed phenotype of dgat1-1 plip1-2 lines, differential expression (DE) analysis for genes involved in hormone metabolism was performed. Upregulation of expression was observed for genes involved in promoting abscisic acid (ABA) response, which led us to specuate the role of altered hormone metabolism in delayed germination of dgat1-1 seeds. Development of allopolyploid Brassica species from its diploid progenitors involves duplication, loss, and reshuffling of genes leading to massive genetic redundancy. It leads to selective expression or newly acquired role for duplicated homeologs. Differential expression (DE) analysis for homoeologous genes from A and B subgenomes of allopolyploid B. juncea implicated in FA synthesis, acyl editing, and TAG biosynthesis and metabolism was performed. Differential expression (DE) analysis identified the transcriptional dominance of A subgenome homoeologs. Identification of these homoeologs will enable their use in breeding programs directed towards improvement of lipid content and composition in seeds.

Li, Kwun Yee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 83-88). / Abstract also in Chinese. / Thesis/Assessment Committee --- p.ii / Statement --- p.iii / Abstract --- p.iv / 摘要 --- p.vi / Acknowledgements --- p.vii / Table of Contents --- p.ix / List of Tables --- p.xiii / List of Figures --- p.xiv / List of Abbreviations --- p.xvii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- The Plant Secretory and Endocytic Pathways --- p.2 / Chapter 1.2 --- PVC Proteomics Analysis Led to the Identification of AtEMP --- p.5 / Chapter 1.3 --- EMP70 Family Proteins --- p.5 / Chapter 1.3.1 --- General structure of EMP70 proteins --- p.5 / Chapter 1.3.2 --- EMP70 in other organisms --- p.8 / Chapter 1.3.3 --- EMP70 proteins in Arabidopsis --- p.9 / Chapter 1.4 --- Accession Numbers --- p.10 / Chapter 1.5 --- Research Objectives --- p.14 / Chapter Chapter 2 --- Generation and Characterization of Transgenic Tobacco BY-2 Cell Lines Expressing Selective AtEMP-GFP Fusions --- p.15 / Chapter 2.1 --- Introduction --- p.16 / Chapter 2.2 --- Materials and Methods --- p.17 / Chapter 2.2.1 --- RNA extraction and cDNA generation --- p.17 / Chapter 2.2.2 --- Construct making --- p.18 / Chapter 2.2.3 --- Bacterial strains --- p.21 / Chapter 2.2.4 --- Transformation of BY-2 cells --- p.21 / Chapter 2.2.5 --- Confocal fluorescence screening of tobacco BY-2 cells --- p.23 / Chapter 2.2.6 --- Drug treatments --- p.23 / Chapter 2.3 --- Results --- p.25 / Chapter 2.3.1 --- Western blot analysis of tobacco BY-2 cell lines expressing AtEMP-GFP fusions --- p.25 / Chapter 2.3.2 --- Subcellular localization of AtEMP-GFP fusions to the PVC in transgenic BY-2 cells --- p.27 / Chapter 2.4 --- Summary --- p.30 / Chapter Chapter 3 --- Generation and Characterization of Antibodies Against Various AtEMPs --- p.31 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Materials and Methods --- p.33 / Chapter 3.2.1 --- Generation of antibodies --- p.33 / Chapter 3.2.2 --- Screening of antibodies --- p.36 / Chapter 3.2.2.1 --- SDS-PAGE and western blot analysis --- p.36 / Chapter 3.2.2.2 --- Confocal immunofluorescence studies --- p.38 / Chapter 3.3 --- Results --- p.39 / Chapter 3.3.1 --- AtEMP antibodies recognized EMP70 proteins in plant cells --- p.39 / Chapter 3.3.2 --- Organelles marked by anti-AtEMPs are closely associated with the Golgi apparatus --- p.40 / Chapter 3.4 --- Summary --- p.49 / Chapter Chapter 4 --- Subcellular Localization of GFP-tagged AtEMP Fusions via Transient Expression --- p.50 / Chapter 4.1 --- Introduction --- p.51 / Chapter 4.2 --- Materials and Methods --- p.52 / Chapter 4.2.1 --- Making of transient expression constructs --- p.52 / Chapter 4.2.2 --- Transient expression --- p.57 / Chapter 4.3 --- Results --- p.59 / Chapter 4.3.1 --- PVC localization of AtEMP-GFP fusions --- p.59 / Chapter 4.3.2 --- Golgi localization of GFP-AtEMP and GFP-AtEMP-S fusions --- p.62 / Chapter 4.4 --- Summary --- p.66 / Chapter Chapter 5 --- Immunogold Electron Microscope Localization of AtEMPs --- p.67 / Chapter 5.1 --- Introduction --- p.68 / Chapter 5.2 --- Materials and Methods --- p.68 / Chapter 5.2.1 --- High-pressure freezing / freeze substitution --- p.68 / Chapter 5.2.2 --- Ultra-thin sectioning --- p.69 / Chapter 5.2.3 --- Immunogold labeling --- p.69 / Chapter 5.2.4 --- Post-staining and transmission election microscopy --- p.69 / Chapter 5.3 --- Results and Summary --- p.70 / Chapter Chapter 6 --- Discussion and Future Perspectives --- p.74 / Chapter 6.1 --- Hypothesis --- p.75 / Chapter 6.2 --- Subcellular localization of AtEMPs --- p.76 / Chapter 6.2.1 --- GFP-tagged AtEMP fusions --- p.76 / Chapter 6.2.2 --- Endogenous EMP70 proteins in BY-2 cells --- p.77 / Chapter 6.3 --- Targeting motifs in AtEMPs --- p.79 / Chapter 6.4 --- Conclusions --- p.81 / Chapter 6.5 --- Future perspectives --- p.82 / Chapter 6.5.1 --- Targeting motifs --- p.82 / Chapter 6.5.2 --- Functional studies --- p.82 / References --- p.83