Plant Breeding and Genetics Commons^™

Analysis Of Ac/Ds Activation Tagged Mutants In Tomato (Solanum Lycopersicum), Ipeleng Randome

Graduate Theses and Dissertations

Tomato (Solanum lycopersicum) is a crop of immense economic and nutritional importance worldwide and also a good model organism for genomic studies of other dicot species. The recent completion of the tomato genome sequence is a great milestone towards learning about the tomato genome. Elucidation of the function of the different genes using different functional genomic tools is therefore important in adding to this resource. To this end, we have developed an Ac-Ds transposon ‘activation tagging’ (ATag) system to be able to transpose transposon inserts, bearing a strong 35S-enhancer element, all around the genome. An Ac-Ds ATag construct was used …

Short Day Transcriptomic Programming During Induction Of Dormancy In Grapevine, Anne Fennell, Karen A. Schlauch, Satyanarayana Gouthu, Laurent G. Deluc, Vedbar Khadka, Lekha Sreekantan, Jerome Grimplet, Grant C. Cramer, Katherine L. Mathiason

Agronomy, Horticulture and Plant Science Faculty Publications

Bud dormancy in grapevine is an adaptive strategy for the survival of drought, high and low temperatures and freeze dehydration stress that limit the range of cultivar adaptation. Therefore, development of a comprehensive understanding of the biological mechanisms involved in bud dormancy is needed to promote advances in selection and breeding, and to develop improved cultural practices for existing grape cultivars. The seasonally indeterminate grapevine, which continuously develops compound axillary buds during the growing season, provides an excellent system for dissecting dormancy, because the grapevine does not transition through terminal bud development prior to dormancy. This study used gene expression …

Chlorophyll Synthase Under Epigenetic Surveillance Is Critical For Vitamin E Synthesis, And Altered Expression Affects Tocopherol Levels In Arabidopsis, Chunyu Zhang, Wei Zhang, Guodong Ren, Denli Li, Rebecca E. Cahoon, Ming Chen, Yongming Zhou, Bin Yu, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Chlorophyll synthase catalyzes the final step in chlorophyll biosynthesis: the esterification of chlorophyllide with either geranylgeranyl diphosphate or phytyl diphosphate (PDP). Recent studies have pointed to the involvement of chlorophyll-linked reduction of geranylgeranyl by geranylgeranyl reductase as a major pathway for the synthesis of the PDP precursor of tocopherols. This indirect pathway of PDP synthesis suggests a key role of chlorophyll synthase in tocopherol production to generate the geranylgeranyl-chlorophyll substrate for geranylgeranyl reductase. In this study, contributions of chlorophyll synthase to tocopherol formation in Arabidopsis (Arabidopsis thaliana) were explored by disrupting and altering expression of the corresponding gene …

Bioenergy And African Transformation, Lee R. Lynd, Mariam Sow, Annie Chimphango, Luis Cortez, Carlos H. Brito Cruz, Mosad Elmissiry, Mark Laser

Dartmouth Scholarship

Among the world’s continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some …

Transport Regimes And Spread Of The Common Reed, Phramites Australis, In The Saco River, Me, Usa, Michelle A. Slater

All Theses And Dissertations

Allee effects are important to species invasions because population growth may be limited by low outcrossing potential in newly founded populations leading to depressed levels of fitness. Non-native Phragmites australis (common reed) has been present in the United States for over 200 years, but has been slow to reach some areas, possibly owing to the Allee phenomenon, whereby young or isolated Phragmites patches with initially low genotypic richness are slow to recruit viable seedlings due to inbreeding, which limits the rate of patch expansion. In order to explore the importance of the Allee effect in a recently invaded system, the …

Osmotic Stress Induces Phosphorylation Of Histone H3 At Threonine 3 In Pericentromeric Regions Of Arabidopsis Thaliana, Zhen Wang, Juan Armando Casas-Mollano, Jianping Xu, Jean-Jack M. Riethoven, Chi Zhang, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Histone phosphorylation plays key roles in stress-induced transcriptional reprogramming in metazoans but its function(s) in land plants has remained relatively unexplored. Here we report that an Arabidopsis mutant defective in At3g03940 and At5g18190, encoding closely related Ser/Thr protein kinases, shows pleiotropic phenotypes including dwarfism and hypersensitivity to osmotic/salt stress. The double mutant has reduced global levels of phosphorylated histone H3 threonine 3 (H3T3ph), which are not enhanced, unlike the response in the wild type, by drought-like treatments. Genome-wide analyses revealed increased H3T3ph, slight enhancement in trimethylated histone H3 lysine 4 (H3K4me3), and a modest decrease in histone H3 occupancy …

Osmotic Stress Induces Phosphorylation Of Histone H3 At Threonine 3 In Pericentromeric Regions Of Arabidopsis Thaliana, Zhen Wang, Juan Casas-Mollano, Jianping Xu, Jean-Jack Riethoven, Chi Zhang, Heriberto D. Cerutti

Center for Plant Science Innovation: Faculty Publications

Histone phosphorylation plays key roles in stress-induced transcriptional reprogramming in metazoans but its function(s) in land plants has remained relatively unexplored. Here we report that an Arabidopsis mutant defective in At3g03940 and At5g18190, encoding closely related Ser/Thr protein kinases, shows pleiotropic phenotypes including dwarfism and hypersensitivity to osmotic/salt stress. The double mutant has reduced global levels of phosphorylated histone H3 threonine 3 (H3T3ph), which are not enhanced, unlike the response in the wild type, by drought-like treatments. Genome-wide analyses revealed increased H3T3ph, slight enhancement in trimethylated histone H3 lysine 4 (H3K4me3), and a modest decrease in histone H3 occupancy …

Biochemical And Proteomic Profiling Of Maize Endosperm Texture And Protein Quality, Kyla J. Morton

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The research described herein, focuses on the biochemical and proteomic analysis of the maize endosperm and what influences kernel texture. Quality Protein Maize (QPM) is a hard endosperm version of the high-lysine opaque2 (o2) mutant but the genes involved in modifying the soft o2 endosperm are unknown. Pyrophosphate (PPi)-dependent fructose 6-phosphate 1-phosphotransferase (PFP) catalyzes the ATP-independent conversion of fructose 6-phosphate to fructose 1, 6-bisphosphate in glycolysis. We found a large increase in transcript and protein levels of the alpha regulatory subunit of PFP (PFPα) in QPM endosperm. In vitro enzyme assays show a significant increase in forward PFP …

Alternative Restoration Treatments To Maximize Growth And Survival Of Tamaulipan Thornscrub Species During Seeding Establishment, Jennifer Lynn Vela

Theses and Dissertations - UTB/UTPA

Anthropogenic activities that destroy, degrade, or fragment terrestrial ecosystems have long-lasting detrimental impacts on ecosystem function, services, and biodiversity. The Tamaulipan thornscrub ecoregion of south Texas and northeastern Mexico has sustained considerable loss, degradation, and fragmentation due land conversion for agriculture, urbanization, and introduction of invasive flora and fauna. In an attempt to restore habitat for endangered and migratory animals, United States Fish and Wildlife Service has undertaken a large-scale thornscrub revegetation effort in south Texas. The goal of this study was to develop effective restoration techniques to promote growth and survival of Tamaulipan thornscrub species during seedling establishment. Beginning …

Physiological Responses Of Cotton Genotypes To Water-Deficit Stress During Reproductive Development, Cristiane Pilon

Graduate Theses and Dissertations

Drought stress is one of the major abiotic factors affecting crop growth and limiting production worldwide. Cotton genotypes vary in drought tolerance, and the effects of drought stress on the anatomy and physiology of cotton leaves and roots have been reported. However, information on physiological and metabolic processes of leaves and flowers of modern cotton cultivars under water-deficit stress during reproductive development is not well elucidated. It was hypothesized that water-deficit stress during squaring and flowering stages would impair stomatal conductance and photosynthetic efficiency of leaves, which consequently would result in osmotic adjustment through accumulation of compatible solutes, increased activity …

Association Mapping For Elemental Concentration Resulting From Vegetative Stage Soil Waterlogging Stress In Wheat (Triticum Aestivum L.), Maria Nelly Arguello-Blanco

Graduate Theses and Dissertations

Soil waterlogging (WL) affects wheat production worldwide, including the southern of the U.S. Little is known about the genetics of tolerance mechanisms to WL, particularly of potentially toxic elements such as aluminum, iron and sodium. The objectives of this study were to use association mapping (AM) to identify SNP associated with the EC in the vegetative tissue of a set of 240 diverse soft winter wheat genotypes (AM panel) grown under field WL and to determine the impact of WL on wheat yield (GY) and yield components in a set 28 adapted cultivars (YT)

YT study showed reductions in GY …

Combinatorial Effects Of Fatty Acid Elongase Enzymes On Nervonic Acid Production In Camelina Sativa, Dongxin Huai, Yuanyuan Zhang, Chunyu Zhang, Edgar B. Cahoon, Yongming Zhou

Center for Plant Science Innovation: Faculty Publications

Very long chain fatty acids (VLCFAs) with chain lengths of 20 carbons and longer provide feedstocks for various applications; therefore, improvement of VLCFA contents in seeds has become an important goal for oilseed enhancement. VLCFA biosynthesis is controlled by a multi-enzyme protein complex referred to as fatty acid elongase, which is composed of β-ketoacyl-CoA synthase (KCS), β-ketoacyl-CoA reductase (KCR), β-hydroxyacyl-CoA dehydratase (HCD) and enoyl reductase (ECR). KCS has been identified as the ratelimiting enzyme, but little is known about the involvement of other three enzymes in VLCFA production. Here, the combinatorial effects of fatty acid elongase enzymes on VLCFA production …

Genetic Diversity Of Miscanthus In The Us Naturalized Populations Based On Molecular Marker, Suma Basak

College of Agriculture, Environment and Nutrition Sciences Graduate Theses and Dissertations

ABSTRACT

Miscanthus is a fast growing bioenergy grass, tolerant of adverse conditions and has high biomass production, and is increasingly attractive as a potential source of cellulosic ethanol. An understanding of genetic variation in naturalized populations of Miscanthus in the US may help in selecting appropriate parents for breeding superior cultivars that are adapted in the wide-ranging and changing environments. The molecular marker analysis of Miscanthus is an important tool towards the genetic improvement program of this bioenergy grass. As sugarcane is closely related to Miscanthus, we employed its DNA markers as probes to explore genetic diversity within and among …

Anaerobic Detoxification Of Acetic Acid In A Thermophilic Ethanologen, A Joe Shaw, Bethany B. Miller, Stephen R. Rogers, William Robert Kenealy, Alex Meola, Ashwini Bhandiwad, W Ryan Sillers, Indraneel Shikhare, David Hogsett, Christopher Herring

Dartmouth Scholarship

The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield. We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum.

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Genetic Mapping Of Yield And Normalized Difference Vegetative Index In Soft Red Winter Wheat (Triticum Aestivum L.), Christopher Keith Addison

Graduate Theses and Dissertations

Wheat is the most widely cultivated cereal crop, being grown on 17% of the global crop land and as such must be adapted to an array of environmental stresses. In order to become a variety, wheat breeding lines must be tested across a range of environments for both high productivity and stability. Quantitative trait loci (QTL) mapping and indices are tools that can aid plant breeders in the selection of superior lines. Soft red winter wheat accounts for 20% of the total wheat production in the United States, being grown in the southeastern U.S. predominantly along the Mississippi River. However, …

Sumoylation By A Stress-Specific Small Ubiquitin-Like Modifier E2 Conjugase Is Essential For Survival Of Chlamydomonas Reinhardtii Under Stress Conditions, Amy R. Knobbe, Kempton M. Horken, Thomas M. Plucinak, Eniko Balassa, Heriberto Cerutti, Donald P. Weeks

Center for Plant Science Innovation: Faculty Publications

Posttranslational modification of proteins by small ubiquitin-like modifier (SUMO) is required for survival of virtually all eukaryotic organisms. Attachment of SUMO to target proteins is catalyzed by SUMO E2 conjugase. All haploid or diploid eukaryotes studied to date possess a single indispensable SUMO conjugase. We report here the unanticipated isolation of a Chlamydomonas reinhardtii (mutant5 [mut5]), in which the previously identified SUMO conjugase gene C. reinhardtii ubiquitin-conjugating enzyme9 (CrUBC9) is deleted. This surprising mutant is viable and unexpectedly displays a pattern of protein SUMOylation at 25°C that is essentially identical to wild-type cells. However, unlike wild-type …

Toward Production Of Jet Fuel Functionality In Oilseeds: Identification Of Fatb Acyl-Acyl Carrier Protein Thioesterases And Evaluation Of Combinatorial Expression Strategies In Camelina Seeds, Hae Jin Kim, Jillian E. Silva, Hieu Sy Vu, Keithanne Mockaitis, Jeong-Won Nam, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Seeds of members of the genus Cuphea accumulate medium-chain fatty acids (MCFAs; 8:0–14:0). MCFA- and palmitic acid- (16:0) rich vegetable oils have received attention for jet fuel production, given their similarity in chain length to Jet A fuel hydrocarbons. Studies were conducted to test genes, including those from Cuphea, for their ability to confer jet fuel-type fatty acid accumulation in seed oil of the emerging biofuel crop Camelina sativa. Transcriptomes from Cuphea viscosissima and Cuphea pulcherrima developing seeds that accumulate >90% of C8 and C10 fatty acids revealed three FatB cDNAs (CpuFatB3, CvFatB1, and CpuFatB4 …

Fungal Morphogenesis, Xiaorong Lin, J. Andrew Alspaugh, Haoping Liu, Steven D. Harris

Center for Plant Science Innovation: Faculty Publications

Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and …

Gene Silencing In Microalgae: Mechanisms And Biological Roles, Eun-Jeong Kim, Xinrong Ma, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Microalgae exhibit enormous diversity and can potentially contribute to the production of biofuels and high value compounds. However, for most species, our knowledge of their physiology, metabolism, and gene regulation is fairly limited. In eukaryotes, gene silencing mechanisms play important roles in both the reversible repression of genes that are required only in certain contexts and the suppression of genome invaders such at transposons. The recent sequencing of several algal genomes is providing insights into the complexity of these mechanisms in microalgae. Collectively, glaucophyte, red, and green microalgae contain the machineries involved in repressive histone H3 lysine methylation, DNA cytosine …

Sirna-Directed Dna Methylation In Plants, Meng Xie, Bin Yu

Center for Plant Science Innovation: Faculty Publications

DNA cytosine methylationis an important epigenetic process that is correlated with transgene silencing, transposon suppression, and gene imprinting. In plants, small interfering RNAs (siRNAs) can trigger DNA methylation at loci containing their homolog sequences through a process called RNAdirected DNA methylation (RdDM). In canonical RdDM, 24 nucleotide (nt) siRNAs (ra-siRNAs) will be loaded into their effector protein called ARGONAUTE 4 (AGO4) and subsequently targeted to RdDM loci through base-pairing with the non-coding transcripts produced by DNA-directed RNA Polymerase V. Then, the AGO4-ra-siRNA will recruit the DNA methyltransferase to catalyze de novo DNA methylation. Recent studies also identified non-canonical RdDM pathways …