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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

Plant Biology

Publication Year

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Analysis Of The Role Of Rns2 And Autophagy In The Turnover Of Ribosomal Rna In Arabidopsis Thaliana, Brice Edward Floyd Jan 2015

Analysis Of The Role Of Rns2 And Autophagy In The Turnover Of Ribosomal Rna In Arabidopsis Thaliana, Brice Edward Floyd

Graduate Theses and Dissertations

The degradation and turnover of cellular components is essential for biological systems to remove damaged components and maintain functional intracellular contents. Autophagy is a vesicle-mediated process by which cellular contents can be degraded through trafficking to the lysosome or vacuole where lytic processes occur. The majority of a cell’s RNA and large quantities of its protein can be found in ribosomes. Ribosomes represent a significant metabolic investment. However, little is known about the turnover of these highly abundant ribonuclear organelles in plants.

RNase T2 enzymes represent a widely conserved class of ribonucleases present in the genomes of nearly all ...


Plant Molecular Farming For The Production Of Industrial Enzyme And Vaccines, Hartinio N. Nahampun Jan 2015

Plant Molecular Farming For The Production Of Industrial Enzyme And Vaccines, Hartinio N. Nahampun

Graduate Theses and Dissertations

Since the realization of plant genetic modification, transgenic plants have been utilized as platform for the production of valuable recombinant proteins or also known as plant molecular farming (PMF). The plant offers an economical system to reduce cost, the possibility of large scale production and is free of pathogens. The plant also provides versatility o products to accumulate from industrial enzymes, peptides, and pharmaceuticals. Recent advancement of RNA as regulator of gene expression and antiviral responses has shown a new area of research where transgenic plants are used to accumulate therapeutic RNAs. In this study, the reliability of transgenic plants ...


Investigating The Roles Of Diterpenoids In Rice-Xanthomonas Oryzae Interactions, Xuan Lu Jan 2015

Investigating The Roles Of Diterpenoids In Rice-Xanthomonas Oryzae Interactions, Xuan Lu

Graduate Theses and Dissertations

Secondary metabolites play a significant role in mediating plant-microbe interactions. Rice (Oryza sativa) is one of the most important staple crops. Once rice is attacked by microbial pathogens, it will produce phytoalexins antibiotics to defend against enemies such as the bacterial pathogen Xanthomonas oryzae. Diterpenoids provide a rich source of metabolites mediating rice-X. oryzae interaction. First, gibberellin (GA), as complex diterpenoid phytohormone, besides the profound effects on plant growth and development, it has been shown to negatively regulate rice defense. Interestingly, we found a putative GA biosynthetic gene operon in rice bacterial leaf streak pathogen Xanthomonas oryzae pv. oryzicola (Xoc ...


Functional And Genomic Analyses Of The Maize Yabby Transcription Factors Drooping Leaf1 And Drooping Leaf2, Joshua Strable Jan 2015

Functional And Genomic Analyses Of The Maize Yabby Transcription Factors Drooping Leaf1 And Drooping Leaf2, Joshua Strable

Graduate Theses and Dissertations

Leaf and floral architectures contribute significantly to crop yield. Leaf architecture, i.e., leaf length, width and angle, defines canopy structure, which influences light penetration, photoassimilate production and overall plant fitness. In the cereals, floral architecture defines the production and arrangement of the structures that bear grain, directly impacting yield. A major challenge in plant biology is to understand the genetic factors that regulate the development of leaf and flower parts, seemingly disparate, but evolutionarily related structures, in the grasses. We discovered and characterized a novel maize (Zea mays spp. mays) mutant we named drooping leaf1 (drl1), as acutely flaccid ...


Host Target Genes Of The Xanthomonas Oryzae Pv. Oryzae Type Iii Effectors For Bacterial Blight In Rice, Junhui Zhou Jan 2015

Host Target Genes Of The Xanthomonas Oryzae Pv. Oryzae Type Iii Effectors For Bacterial Blight In Rice, Junhui Zhou

Graduate Theses and Dissertations

Xanthomonas oryzae pv. oryzae is the causal agent of the bacterial blight in rice, which invades the host rice plant through injecting a myriad of effector proteins through a structure called type Ⅲ secretion system, thereafter, these effectors are also called type Ⅲ effectors. There are two groups of type Ⅲ effectors: TAL (Transcription Activator-Like) effectors that specifically bind to the promoter region of particular host genes and regulate host gene transcription and Non-TAL effectors that bind to host gene products and manipulate the host immune system.

In this thesis, I present the work of three projects. First, I, and ...


The Molecular Mechanisms Of Brassinosteroid-Regulated Drought Stress Response In Arabidopsis Thaliana, Buyun Tang Jan 2015

The Molecular Mechanisms Of Brassinosteroid-Regulated Drought Stress Response In Arabidopsis Thaliana, Buyun Tang

Graduate Theses and Dissertations

Brassinosteroids (BRs) are involved in diverse developmental processes such as cell elongation, vascular differentiation, senescence and stress response. The mechanisms and regulatory networks of BR-regulated plant growth and development have been well described for the past decade with the identification of receptors, kinases and central transcription factors involved in BR signaling. Recent studies revealed BRs also extensively participated in plant response to environmental stresses, although the mechanisms of BR-regulated stress response is largely unknown. Coordination of plant growth and stress response requires integration of multiple signaling output through hormonal crosstalk. Studies of BR signaling pathway and BR-mediated physiological responses indicate ...


Ribosomal Frameshifting Directed By A Potyvirid Sequence Motif In Diverse Translation Systems, Alice Y. Hui Jan 2015

Ribosomal Frameshifting Directed By A Potyvirid Sequence Motif In Diverse Translation Systems, Alice Y. Hui

Graduate Theses and Dissertations

The family, Potyviridae, contains a third of all known plant viruses within eight genera. The genome is translated as one large polyprotein from which ten mature proteins are proteolytically cleaved. Recently, discovery of a protein translated from an overlapping reading frame (pipo) proved essential in systemic plant infection. It is hypothesized to translate via a ribosomal frameshift, change in reading frame during the elongation phase of translation. The cryptic programmed ribosomal frameshift signal had been undetected until now because it lacks the canonical characteristics: slippery sequence, spacer sequence, and RNA secondary structure, in that order. Only one of the three ...


New Insights Into The Functional Organization Of Xyloglucan Biosynthetic Enzymes And Their Catalytic Mechanism, Yi-Hsiang Chou Jan 2014

New Insights Into The Functional Organization Of Xyloglucan Biosynthetic Enzymes And Their Catalytic Mechanism, Yi-Hsiang Chou

Graduate Theses and Dissertations

Xyloglucan (XyG) is the major hemicellulosic polysaccharide in the primary cell walls of most vascular dicotyledonous plants, and has important structural and physiological functions in plant growth and development. In Arabidopsis thaliana, a glucan synthase CSLC4, three xylosyltransferases, XXT1, XXT2, and XXT5, two galactosyltransferase, MUR3 and XLT2 and a fucosyltransferase, FUT1 synthesize xyloglucan in Golgi. The functional organization of these enzymes is not clear. To study the functional organization of these enzymes, Bimolecular Fluorescence Complementation (BiFC), in vitro pull-down assay and co-immunoprecipitation were used to elucidate the interactions among CSLC4, XXTs, MUR3, XLT2 and FUT1 proteins both in vivo and ...