Life Sciences Commons^™

An Evaluation Of Hybrid Traits, Yield, And Major Qtl Effect On Heterosis In Hybrid Soft Red Winter Wheat, Zachary James Winn

Graduate Theses and Dissertations

Wheat (Triticum aestivum L.) is a self-pollinating species that is most often bred as a recombinant inbred line. When two inbred individuals are crossed, they produce progeny which experience heterosis; heterosis is the increased robustness experienced due to the reintroduction of heterozygosity. Hybrid wheat may be produced through the use of chemical hybridization agents, yet the structure of wheat flowers decreases the efficiency of outcrossing. The objectives of this study were to: assess the amount of heterosis experienced by a population of hybrid wheat and observe the effect of major gene loci on yield and yield components, phenotype anthers extruded …

Analyzing Multigene Stacking And Genome Editing Strategies In Rice, Bhuvan Pathak

Graduate Theses and Dissertations

Crop improvement through biotechnology is an integrated effort, incorporating multiple approaches like integration of genes, editing of native genes, and removal of selection marker genes. Before streamlining the protocols, the efficiency and feasibility of the individual approach and their components must be tested. This study evaluated following approaches: 1) stacking an array of genes into a single locus by site-specific integration via Cre-lox recombination in rice, 2) determining the efficiency of I-SceI and the CCR5-ZFN in the targeted excisions of gene fragments in rice and Arabidopsis, and 3) determining the efficiency of CRISPR/Cas9 in generating targeted mutations for genome editing …

Qtl Mapping Of Panicle Architecture And Yield-Related Traits Between Two U.S. Rice Cultivars 'Lagrue' And 'Lemont', Adam D. Rice

Graduate Theses and Dissertations

Grain yield in rice consists of multiple yield components such as number of panicles/plant, number of tillers/plant, and number of seeds/panicle. Panicle architecture is an important yield trait yield as the number of seeds on a panicle greatly contributes to the overall panicle yield. A QTL analysis and mapping study on panicle architecture and yield-related traits was performed to identify major QTL and candidate genes associated with the traits. The first objective of the project was to do a yield study evaluating 15 agronomic traits between each of the four U.S. rice cultivars, ‘LaGrue’, ‘Lemont’, ‘Bengal’, and ‘Mars’, to determine …

Phenotypic Study Of Anthracnose Resistance In Black Walnut And Building A Mapping Population, Sadie D. Land

MSU Graduate Theses

Black walnut anthracnose, caused by Gnomonia leptostyla, is the most widespread and destructive disease affecting black walnut trees (Juglans nigra). Breeding cultivars for a higher resistance to anthracnose is a natural and efficient strategy for improving the health and production quality of black walnut trees. The two goals of this study were to reveal that the ‘Sparrow’ cultivar of black walnut contains a significantly higher resistance to anthracnose than the ‘Football’ cultivar when separated from environmental factors, and to expand the ‘Football’ × ‘Sparrow’ F1 mapping population to evaluate how the trait of resistance is inherited in the progeny. A …

Varying Weed Densities Alter The Corn Transcriptome, Highlighting A Core Set Of Weed-Induced Genes And Processes With Potential For Manipulating Weed Tolerance, David P. Horvath, Sharon A. Clay, Stephanie A. Bruggeman, James V. Anderson, Wun S. Chao, Kathleen Yeater

Agronomy, Horticulture and Plant Science Faculty Publications

The phenological responses of corn (Zea mays L.) to competition with increasing densities of winter canola (Brassica napus L.) as the weedy competitor were investigated. Changes in the corn transcriptome resulting from varying weed densities were used to identify genes and processes responsive to competition under controlled conditions where light, nutrients, and water were not limited. Increasing densities of weeds resulted in decreased corn growth and development and increased the number and expression intensity of competition-responsive genes. The physiological processes identified in corn that were consistently induced by competition with weeds included protein synthesis and various transport functions. …

Identification Of Quantitative Trait Loci (Qtls) For Resistance To Fusarium Head Blight (Fhb) In Wheat Variety Ags 2060 And Evaluation Of The Effect Of Fhb1 Resistance Gene On Fhb Reaction In A Louisiana Wheat Breeding Population, Alejandro Castro Aviles

LSU Doctoral Dissertations

Fusarium head blight (FHB), caused by the fungus Fusarium spp., is a disease that attacks several grass species, including wheat. Wheat variety AGS 2060 has remained moderately susceptible to FHB and is regularly found in pedigrees of resistant breeding lines. Quantitative trait loci (QTL) mapping was conducted to find sources of resistance to FHB in AGS 2060. A 90K SNP chip was used to genotype a double haploid mapping population produced from a cross between wheat varieties AGS 2060 and AGS 2035. There were highly significant differences between lines in the population for Fusarium damaged kernels (FDK) rating and deoxynivalenol …

Supersweet Sweet Corn Cultivar Evaluation For Northern Indiana, 2019, Elizabeth Maynard

Midwest Vegetable Trial Reports

This paper reports on fifteen bicolor, four yellow, and one white supersweet sweet corn entries that were evaluated at the Pinney Purdue Agricultural Center in Wanatah, Indiana.

Phomopsis Stem Canker Of Sunflower In North America: Correlation With Climate And Solutions Through Breeding And Management, Brent S. Hulke, Samuel G. Markell, Nolan C. Kane, Febina M. Mathew

Febina Mathew

Climate change is occurring in the central US and is interacting with agroecological factors to increase biotic stress in sunflower. Certain species of Diaporthe cause Phomopsis stem canker in sunflower and other dicotyledonous weeds and crops. The increase in precipitation already observed in the states of North Dakota, South Dakota, and Minnesota have increased the chances of outbreaks of necrotrophic pathogens, like Diaporthe. We discuss how climate trends, combined with technological, management, and economic interactions, are correlated with increasing incidence of Phomopsis stem canker in these and adjacent areas in North America. Further, we discuss management options and the …

Molecular Systematics Of Isoëtes (Isoëtaceae) In Eastern North America, Peter William Schafran

Biological Sciences Theses & Dissertations

Isoëtes (Isoëtaceae, Isoetales, Lycopodiophyta) is a cosmopolitan genus of aquatic lycophytes, occurring on every continent except Antarctica. Of approximately 200 total taxa, about half are in a clade of species mostly occurring in North and South America. Eastern North America accounts for 22% of global taxonomic diversity, containing 32 fertile taxa and 16 named hybrids. This taxonomic diversity is built upon relatively little morphological difference, and even combined with phylogenetic analysis using several nuclear and chloroplast DNA markers, no well-resolved systematic treatment within this clade exists.

This study aims to clarify the relationships between all species and subspecies of Isoëtes …

Summaries Of Arkansas Cotton Research 2018, Fred Bourland

Arkansas Agricultural Experiment Station Research Series

Arkansas ended the 2018 season ranked 5th nationally in harvested acres (480,000 acres), 4th in lint yield (1150 lb/acre), and 4th in total production (1,150,000 bales). The string of consecutive years with good yields is helping to drive the increase in cotton acres. Harvest and ginning capacity is a major limiting factor for acre expansion. Cotton planting intentions for 2019 released in late March are at 580,000 acres, up 20% from the 485,000 acres planted in 2018. This continues to push the ginning capacity of 28 gins in 2018 and on-farm picker capacity to the limit. Optimism for cotton is …

Nature-Guided Synthesis Of Advanced Bio-Lubricants, Trevor Romsdahl, Asghar Shirani, Robert E. Minto, Chunyu Zhang, Edgar B. Cahoon, Kent D. Chapman, Diana Berman

Center for Plant Science Innovation: Faculty and Staff Publications

Design of environmentally friendly lubricants derived from renewable resources is highly desirable for many practical applications. Here, Orychophragmus violaceus (Ov) seed oil is found to have superior lubrication properties, and this is based on the unusual structural features of the major lipid species— triacylglycerol (TAG) estolides. Ov TAG estolides contain two non-hydroxylated, glycerol-bound fatty acids (FAs) and one dihydroxylated FA with an estolide branch. Estolide branch chains vary in composition and length, leading to their thermal stability and functional properties. Using this concept, nature-guided estolides of castor oil were synthesized. As predicted, they showed improved lubrication properties similar to Ov …

The Database Of Identified Root-Specific Genes And Their Promoters In Maize, Sorghum, And Soybean, Gleb Moisseyev, Divith Rajagopal, Alix Cui, Kiyoul Park, Edgar B. Cahoon, Chi Zhang

Center for Plant Science Innovation: Faculty and Staff Publications

Root genes are essential to plants as they dictate factors such as the strength of the plant, reproductivity success, etc. However, in the status quo, studies on root genes are simply ineffective. To be more specific, currently, there are very few online databases of root genes and promoters, which essentially deters root gene studies from being successful. To fix this problem, our lab constructed and coded an online database that contains information about the roots of maize, soybean, and sorghum. We collected 1200 root genes and assessed the strength and success of a given gene. This online database of these …

B.R. Wells Arkansas Rice Research Studies 2018, R. J. Norman, K. A.K. Moldenhauer

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

Assessing Anthocyanin Biosynthesis In Solanaceae As A Model Pathway For Secondary Metabolism, Zou Li, Trisha Vickrey, Moira G. Mcnally, Shirley J. Sato, Thomas E. Clemente, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty and Staff Publications

Solanaceae have played an important role in elucidating how flower color is specified by the flavonoid biosynthesis pathway (FBP), which produces anthocyanins and other secondary metabolites. With well-established reverse genetics tools and rich genomic resources, Solanaceae provide a robust framework to examine the diversification of this well-studied pathway over short evolutionary timescales and to evaluate the predictability of genetic perturbation on pathway flux. Genomes of eight Solanaceae species, nine related asterids, and four rosids were mined to evaluate variation in copy number of the suite of FBP enzymes involved in anthocyanin biosynthesis. Comparison of annotation sources indicated that the NCBI …

Network‐Based Feature Selection Reveals Substructures Of Gene Modules Responding To Salt Stress In Rice, Qian Du, Malachy Campbell, Huihui Yu, Kan Liu, Harkamal Walia, Qi Zhang, Chi Zhang

Center for Plant Science Innovation: Faculty and Staff Publications

Rice, an important food resource, is highly sensitive to salt stress, which is directly related to food security. Although many studies have identified physiological mechanisms that confer tolerance to the osmotic effects of salinity, the link between rice genotype and salt tolerance is not very clear yet. Association of gene co‐expression network and rice phenotypic data under stress has penitential to identify stress‐responsive genes, but there is no standard method to associate stress phenotype with gene co‐expression network. A novel method for integration of gene co‐expression network and stress phenotype data was developed to conduct a system analysis to link …

Gene Expression Programs During Shoot, Root, And Callus Development In Arabidopsis Tissue Culture, Ping Che, Sonia Lall, Dan Nettleton, Stephen H. Howell

Dan Nettleton

Shoots can be regenerated from Arabidopsis (Arabidopsis thaliana) root explants in tissue culture through a two-step process requiring preincubation on an auxin-rich callus induction medium. Regenerating tissues can be directed along different developmental pathways leading to the formation of shoots, new roots, or callus by transferring to the appropriate organ induction medium. Using gene-profiling methods, we identified groups of genes that serve as molecular signatures of the different developmental processes, i.e. genes that were specifically up- or down-regulated on one developmental pathway, but not on others. One transcription factor gene that was up-regulated during early shoot development was …

Hierarchical Modeling And Differential Expression Analysis For Rna-Seq Experiments With Inbred And Hybrid Genotypes, Andrew Lithio, Dan Nettleton

Dan Nettleton

The performance of inbred and hybrid genotypes is of interest in plant breeding and genetics. High-throughput sequencing of RNA (RNA-seq) has proven to be a useful tool in the study of the molecular genetic responses of inbreds and hybrids to environmental stresses. Commonly used experimental designs and sequencing methods lead to complex data structures that require careful attention in data analysis. We demonstrate an analysis of RNA-seq data from a split-plot design involving drought stress applied to two inbred genotypes and two hybrids formed by crosses between the inbreds. Our generalized linear modeling strategy incorporates random effects for whole-plot experimental …

Nested Hierarchical Functional Data Modeling And Inference For The Analysis Of Functional Plant Phenotypes, Yuhang Xu, Yehua Li, Dan Nettleton

Dan Nettleton

In a plant science Root Image Study, the process of seedling roots bending in response to gravity is recorded using digital cameras, and the bending rates are modeled as functional plant phenotype data. The functional phenotypes are collected from seeds representing a large variety of genotypes and have a three-level nested hierarchical structure, with seeds nested in groups nested in genotypes. The seeds are imaged on different days of the lunar cycle, and an important scientific question is whether there are lunar effects on root bending. We allow the mean function of the bending rate to depend on the lunar …

Root Type-Specific Reprogramming Of Maize Pericycle Transcriptomes By Local High Nitrate Results In Disparate Lateral Root Branching Patterns, Peng Yu, Jutta A. Baldauf, Andrew Lithio, Caroline Marcon, Dan Nettleton, Chunjian Li, Frank Hochholdinger

Dan Nettleton

The adaptability of root system architecture to unevenly distributed mineral nutrients in soil is a key determinant of plant performance. The molecular mechanisms underlying nitrate dependent plasticity of lateral root branching across the different root types of maize are only poorly understood. In this study, detailed morphological and anatomical analyses together with cell type-specific transcriptome profiling experiments combining laser capture microdissection with RNA-seq were performed to unravel the molecular signatures of lateral root formation in primary, seminal, crown, and brace roots of maize (Zea mays) upon local high nitrate stimulation. The four maize root types displayed divergent branching …

Stability Of Single-Parent Gene Expression Complementation In Maize Hybrids Upon Water Deficit Stress, Caroline Marcon, Anja Paschold, Waqas Ahmed Malik, Andrew Lithio, Jutta A. Baldauf, Lena Altrogge, Nina Opitz, Christa Lanz, Heiko Schoof, Dan Nettleton, Hans-Peter Piepho, Frank Hochholdinger

Dan Nettleton

Heterosis is the superior performance of F1 hybrids compared with their homozygous, genetically distinct parents. In this study, we monitored the transcriptomic divergence of the maize (Zea mays) inbred lines B73 and Mo17 and their reciprocal F1 hybrid progeny in primary roots under control and water deficit conditions simulated by polyethylene glycol treatment. Single-parent expression (SPE) of genes is an extreme instance of gene expression complementation, in which genes are active in only one of two parents but are expressed in both reciprocal hybrids. In this study, 1,997 genes only expressed in B73 and 2,024 genes …

Laser Microdissection Of Narrow Sheath Mutant Maize Uncovers Novel Gene Expression In The Shoot Apical Meristem, Xiaolan Zhang, Shahinez Madi, Lisa Borsuk, Dan Nettleton, Robert J. Elshire, Brent Buckner, Diane Janick-Buckner, Jon Beck, Marja Timmermans, Patrick S. Schnable, Michael J. Scanlon

Dan Nettleton

Microarrays enable comparative analyses of gene expression on a genomic scale, however these experiments frequently identify an abundance of differentially expressed genes such that it may be difficult to identify discrete functional networks that are hidden within large microarray datasets. Microarray analyses in which mutant organisms are compared to nonmutant siblings can be especially problematic when the gene of interest is expressed in relatively few cells. Here, we describe the use of laser microdissection microarray to perform transcriptional profiling of the maize shoot apical meristem (SAM), a ~100-μm pillar of organogenic cells that is required for leaf initiation. Microarray analyses …

The B73 Maize Genome: Complexity, Diversity, And Dynamics, Patrick S. Schnable, Doreen Ware, Kai Ying, Cheng-Ting Yeh, Scott J. Emrich, Yi Jia, Ananth Kalyanaraman, An-Ping Hsia, Yan Fu, Sanzhen Liu, Alan M. Myers, Dan Nettleton, Srinivas Aluru

Dan Nettleton

We report an improved draft nucleotide sequence of the 2.3-gigabase genome of maize, an important crop plant and model for biological research. Over 32,000 genes were predicted, of which 99.8% were placed on reference chromosomes. Nearly 85% of the genome is composed of hundreds of families of transposable elements, dispersed nonuniformly across the genome. These were responsible for the capture and amplification of numerous gene fragments and affect the composition, sizes, and positions of centromeres. We also report on the correlation of methylation-poor regions with Mu transposon insertions and recombination, and copy number variants with insertions and/or deletions, as well …

Loss Of Rna–Dependent Rna Polymerase 2 (Rdr2) Function Causes Widespread And Unexpected Changes In The Expression Of Transposons, Genes, And 24-Nt Small Rnas, Yi Jia, Damon R. Lisch, Kazuhiro Ohtsu, Michael J. Scanlon, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

Transposable elements (TEs) comprise a substantial portion of many eukaryotic genomes and are typically transcriptionally silenced. RNA–dependent RNA polymerase 2 (RDR2) is a component of the RNA–directed DNA methylation (RdDM) silencing pathway. In maize, loss of mediator of paramutation1 (mop1) encoded RDR2 function results in reactivation of transcriptionally silenced Mu transposons and a substantial reduction in the accumulation of 24 nt short-interfering RNAs (siRNAs) that recruit RNA silencing components. An RNA–seq experiment conducted on shoot apical meristems (SAMs) revealed that, as expected based on a model in which RDR2 generates 24 nt siRNAs that suppress expression, most differentially …

Comparative Gene Expression Profiles Between Heterotic And Non-Heterotic Hybrids Of Tetraploid Medicago Sativa, Xuehui Li, Yanling Wei, Dan Nettleton, E. Charles Brummer

Dan Nettleton

Background: Heterosis, the superior performance of hybrids relative to parents, has clear agricultural value, but its genetic control is unknown. Our objective was to test the hypotheses that hybrids expressing heterosis for biomass yield would show more gene expression levels that were different from midparental values and outside the range of parental values than hybrids that do not exhibit heterosis.

Results: We tested these hypotheses in three Medicago sativa (alfalfa) genotypes and their three hybrids, two of which expressed heterosis for biomass yield and a third that did not, using Affymetrix M. truncatula GeneChip arrays. Alfalfa hybridized to approximately 47% …

Complementation Contributes To Transcriptome Complexity In Maize (Zea Mays L.) Hybrids Relative To Their Inbred Parents, Anja Paschold, Yi Jia, Caroline Marcon, Steve Lund, Nick B. Larson, Cheng-Ting Yeh, Stephan Ossowski, Christa Lanz, Dan Nettleton, Patrick S. Schnable, Frank Hochholdinger

Dan Nettleton

Typically, F₁-hybrids are more vigorous than their homozygous, genetically distinct parents, a phenomenon known as heterosis. In the present study, the transcriptomes of the reciprocal maize (Zea mays L.) hybrids B73×Mo17 and Mo17×B73 and their parental inbred lines B73 and Mo17 were surveyed in primary roots, early in the developmental manifestation of heterotic root traits. The application of statistical methods and a suitable experimental design established that 34,233 (i.e., 86%) of all high-confidence maize genes were expressed in at least one genotype. Nearly 70% of all expressed genes were differentially expressed between the two parents and 42%–55% …

Economic Contribution Of The Agricultural Sector To The Arkansas Economy In 2017, Leah English, Jennie Popp, Wayne Miller

Research Reports and Research Bulletins

Agriculture and associated agricultural activities are major contributors to the Arkansas economy. Agriculture is defined as the sum of agricultural production and processing activities, unless otherwise specified, and includes crop and animal production and processing, agricultural support industries, forestry and forest products, and textile goods. Agriculture contributes to the economy through direct agricultural production and value-added processing, and also leads to economic activity in other parts of the economy. This report is the eleventh in a series of reports examining agriculture’s economic contribution to the Arkansas economy. The total economic contribution of agriculture (direct, indirect, and induced effects) on value …

The Maize Brown Midrib2 (Bm2) Gene Encodes A Methylenetetrahydrofolate Reductase That Contributes To Lignin Accumulation, Ho Man Tang, Sanzhen Liu, Sarah Hill-Skinner, Wei Wu, Danielle Reed, Cheng-Ting Yeh, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

The midribs of maize brown midrib (bm) mutants exhibit a reddish‐brown color associated with reductions in lignin concentration and alterations in lignin composition. Here, we report the mapping, cloning, and functional and biochemical analyses of the bm2 gene. The bm2 gene was mapped to a small region of chromosome 1 that contains a putative methylenetetrahydrofolate reductase (MTHFR) gene, which is down‐regulated in bm2 mutant plants. Analyses of multiple Mu‐induced bm2‐Mu mutant alleles confirmed that this constitutively expressed gene is bm2. Yeast complementation experiments and a previously published biochemical characterization show that the bm2 gene encodes a …

Extreme‐Phenotype Genome‐Wide Association Study (Xp‐Gwas): A Method For Identifying Trait‐Associated Variants By Sequencing Pools Of Individuals Selected From A Diversity Panel, Jinliang Yang, Haiying Jiang, Cheng-Ting Yeh, Jianming Yu, Jeffrey A. Jeddeloh, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

Although approaches for performing genome‐wide association studies (GWAS) are well developed, conventional GWAS requires high‐density genotyping of large numbers of individuals from a diversity panel. Here we report a method for performing GWAS that does not require genotyping of large numbers of individuals. Instead XP‐GWAS (extreme‐phenotype GWAS) relies on genotyping pools of individuals from a diversity panel that have extreme phenotypes. This analysis measures allele frequencies in the extreme pools, enabling discovery of associations between genetic variants and traits of interest. This method was evaluated in maize (Zea mays) using the well‐characterized kernel row number trait, which was …

Substantial Contribution Of Genetic Variation In The Expression Of Transcription Factors To Phenotypic Variation Revealed By Erd-Gwas, Hung-Ying Lin, Qiang Liu, Xiao Li, Jinliang Yang, Sanzhen Liu, Yinlian Huang, Michael J. Scanlon, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

Background: There are significant limitations in existing methods for the genome-wide identification of genes whose expression patterns affect traits.

Results: The transcriptomes of five tissues from 27 genetically diverse maize inbred lines were deeply sequenced to identify genes exhibiting high and low levels of expression variation across tissues or genotypes. Transcription factors are enriched among genes with the most variation in expression across tissues, as well as among genes with higher-than-median levels of variation in expression across genotypes. In contrast, transcription factors are depleted among genes whose expression is either highly stable or highly variable across genotypes. We developed a …

Spotted Cotton Oligonucleotide Microarrays For Gene Expression Analysis, Joshua A. Udall, Lex E. Flagel, Foo Cheung, Andrew W. Woodard, Ran Hovav, Ryan Adam Rapp, Jordan M. Swanson, Jinsuk J. Lee, Alan R. Gingle, Dan Nettleton, Christopher D. Town, Z. Jeffrey Chen, Jonathan F. Wendel

Dan Nettleton

Microarrays offer a powerful tool for diverse applications plant biology and crop improvement. Recently, two comprehensive assemblies of cotton ESTs were constructed based on three Gossypium species. Using these assemblies as templates, we describe the design and creation and of a publicly available oligonucleotide array for cotton, useful for all four of the cultivated species. Synthetic oligonucleotide probes were generated from exemplar sequences of a global assembly of 211,397 cotton ESTs derived from >50 different cDNA libraries representing many different tissue types and tissue treatments. A total of 22,787 oligonucleotide probes are included on the arrays, optimized to target the …