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Mutant Drought Phenotype Investigation : A Look Into Effects Of Protein Prenylation On Water Utilization In Conditions Of Varying Soil Saturation And Gene Knockout., Casey Rasmussen

College of Arts & Sciences Senior Honors Theses

Plants respond to environmental stress, such as drought, with increases in levels of Abscisic Acid (ABA). This stress response allows greater survival rates but results in the plants producing lower seed yield and biomass. Certain mutant strains of the Arabidopsis plant have been identified with mutations in coding regions involved in the formation of the α and β subunits of PFT and PGGT-I genes involved in protein prenylation. We explored the possibility of these mutant strains to better preserve seed yield and plant biomass under drought stressing conditions in comparison to the wild type (Columbia) strain, based on the mutants’ …

Uncovering The Molecular Link Between Mir156.Spl15 And Carotenoid Accumulation In Arabidopsis, Davood Emami Meybodi

Electronic Thesis and Dissertation Repository

Carotenoid Cleavage Dioxygenases (CCDs) are an enzyme family that cleaves specific double bonds in carotenoids. MicroR156 in Arabidopsis regulates a network of genes by repressing 10 SPL genes, among which, SPL15 was found to regulate shoot branching and carotenoid accumulation. The expression of CCD1, CCD4, CCD7, CCD8, NCED2, NCED3, NCED5, NCED6, NCED9 and SPL15 was evaluated in siliques at 10 days post anthesis and in 10-day-old roots in Arabidopsis wild type, sk156 (miR156 overexpression mutant), RS105 (miR156 overexpression line), spl15 (SPL15 knockout mutant) and two 35S:SPL15 lines. Results showed that most of CCD/NCED genes were …

Functional Characterization Of Metallothioneins In Arabidopsis And Barley, Nimnara Yookongkaew

Open Access Dissertations

Metalothioneins (MTs) are metal binding proteins that can bind metals such as Cu, Zn, and Cd but the functions of MTs in plants are largely unknown. To understand the function of MTs in Arabidopsis, T-DNA insertion mutants lacking 4 MT genes including MT1a, MT2a, MT2b and MT3 were developed. The quadruple mutant (mt1a/mt2a/mt2b/mt3) showed no visible phenotype under standard growth conditions. However, it accumulated higher Cu in leaves compared to wild type but lower Cu in seeds. Further analysis showed that triple mutants lacking both MT1a and MT2b, which are highly expressed in vascular tissues, had similar …

Study Of Thermotolerance Mechanism In Gossypium Hirsutum Through Identification Of Heat Stress Genes, Jin Zhang

Graduate Theses and Dissertations

ABSTRACT

Heat stress causes major losses to cotton seed and lint yield. Introduction of heat stress tolerance to Arkansas cotton varieties is highly desirable. However, very little is known about the molecular basis of heat stress tolerance in cotton. The present study attempted to identify heat stress tolerance genes in two heat-tolerant cotton cultivars, VH260 and MNH456, originating from Pakistan. Towards this, the expression profile of the cotton orthologs of sevenArabidopsisheat stress tolerance genes was studied in these two cultivars, and compared with the two heat-susceptible cotton cultivars, ST213 and ST4288, originating from Mississippi Delta region. In addition, physiological parameters …

Characterization Of A Putative Activation Domain In The Hulk Gene Family, Christopher Doan

Electronic Thesis and Dissertation Repository

The HULK gene family participates in regulation of both flowering time and development in the plant Arabidopsis thaliana. The proteins encoded by these genes share conserved domain structures including a proline-rich region (PRR) in the carboxyl-terminus. Based on sequence analysis and the presence of a proline-rich domain, it has been suggested that the HULKs are putative transcription factors in which HUA2 is known to regulate several late-flowering genes: FLC, FLM and MAF2.

To investigate the putative transcriptional activation domain in the carboxyl-terminus of the HULKs, full-length HULKs and deletion constructs were 3-AT titrated in yeast-one hybrids. It …

Conserved Noncoding Sequences Regulate Steady-State Mrna Levels In Arabidopsis Thaliana, Jacob Spangler

All Dissertations

Arabidopsis thaliana has undergone three whole genome duplications within its ancestry, and these events have dramatically affected its gene complement. Of the most recent whole genome duplication events (&alpha event), there remain 11,452 conserved noncoding sequences (CNSs) that have been retained proximal to &alpha duplicate gene pairs. As functional DNA elements are expected to diverge in sequence at a slower rate than nonfunctional DNA elements, the retained CNSs likely encode gene regulatory function. Within this dissertation I provide evidence for the regulatory role of CNSs within Arabidopsis thaliana. Using a collection of over 5,000 microarray RNA expression profiling datasets, I …

Metabolism And Transcriptional Responses To Asparagine In Arabidopsis Thaliana, Qianyi Zhang

Electronic Thesis and Dissertation Repository

Asparagine aminotransferase transforms asparagine into α-ketosuccinamate, which is further deamidated by an ω-amidase. Serine:glyoxylate aminotransferase, encoded by AGT1 in Arabidopsis, was identified as asparagine aminotransferase. In the roots of 10-day-old Arabidopsis seedlings treated with 20 mM asparagine, AGT1 transcript levels increased by 2-fold while ω-amidase transcripts were decreased by 30%. Recombinant AGT1 had a substrate preference for asparagine when compared with alanine and serine as amino group donors. An ω-amidase candidate gene, AT5G12040, was identified based on amino acid sequence identity with mammalian gene Nitrilase 2. RT-PCR of a T-DNA insertion mutant line showed that ω-amidase expression was abolished …

Toc Complex Formation: An Investigation Of The Interactions Governing Toc Complex Composition And Assembly, Steven R. Siman

Theses and Dissertations (Comprehensive)

Chloroplast-destined preproteins are translated in the cytosol, and posttranslationally targeted to and translocated across the double envelope membrane of the chloroplast by the coordinated activities of two translocon complexes: the Translocons at the Outer and Inner envelope membrane of the Chloroplast (TOC and TIC, respectively). In the model organism Arabidopsis thaliana the core TOC components include two families of GTPase receptors: TOC159 (atToc159, -132, and -120) and TOC34 (atToc33 and -34). These receptor families are hypothesized to assemble into distinct complexes and recognize transit peptides present on the N-terminus of chloroplast-destined preproteins. The GTPase domains of the TOC159 and TOC34 …

The Role Of Polyadenylation In Seed Germination, Liuyin Ma

Theses and Dissertations--Plant and Soil Sciences

Seed germination has many impacts on the uses of seeds, and is an important subject for study. Seed germination is regulated at both transcriptional and post-transcriptional levels. Therefore, it is important to study how polyadenylation regulates gene expression during seed germination. To this end, a modified Illumina GAIIx sequencing protocol (described in Chapter Two) was developed that allows deep coverage of poly(A) site position and distribution.

Alternative polyadenylation (APA) regulates gene expression by choosing one potential poly(A) site on a precursor RNA consequentially shortening/lengthening the mRNA relative to other possible sites. To further explore this phenomenon, genes affected by APA …