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Development And Evaluation Of Environmentally-Sensitive Genetic Male Sterile Lines For Louisiana Hybrid Rice, Federico Molina Casella 2017 Louisiana State University

Development And Evaluation Of Environmentally-Sensitive Genetic Male Sterile Lines For Louisiana Hybrid Rice, Federico Molina Casella

LSU Doctoral Dissertations

The Louisiana rice industry generates ~ 400 million dollars each year toward our state economy. Louisiana varieties are typically bred as pure lines, but hybrid (F1) varieties have the potential to increase grain yields 15% or more over conventional sources. A primary goal of the LSU AgCenter Hybrid Breeding program is to breed elite cross combinations (hybrid varieties) through development of environmentally sensitive male sterile and fertile pollinator lines. Extensive multi-location yield trials in Louisiana have demonstrated high grain and head rice yields for candidate hybrids, but improvements in maturity, lodging, and grain chalk are needed. To address these challenges ...


Predicted Gains From Recurrent Selection In The Bs11 Maize Population, P. S. Guzman, K. R. Lamkey 2017 Iowa State University

Predicted Gains From Recurrent Selection In The Bs11 Maize Population, P. S. Guzman, K. R. Lamkey

Kendall R Lamkey

Random genetic drift and inbreeding depression resulting from the use of small effective population size limit the gain of recurrent selection programs. The objectives of our study were to predict the gains of S2, S1, full-sib, and modified-ear-to-row recurrent selection methods in maize (Zea mays L.) with varying effective population sizes of 5, 10, 20, and 30 and to compare these predicted gains with the realized gains obtained in a related study. Using the variance estimates of the BS11C0 population, predicted gain cycle-1 was computed based on single trait selection and index selection. Predicted gain cycle-1 for S1-progeny selection method ...


Hardy-Weinberg And Linkage Equilibrium Estimates In The Bsss And Bscb1 Random Mated Populations, J. A. Labate, K. R. Lamkey, M. Lee, W. Woodman 2017 Cornell University

Hardy-Weinberg And Linkage Equilibrium Estimates In The Bsss And Bscb1 Random Mated Populations, J. A. Labate, K. R. Lamkey, M. Lee, W. Woodman

Kendall R Lamkey

Because maize (Zea mays) is an annual species those working with it must frequently make crosses to preserve and periodically maintain populations. Random mating is performed either using hand-pollination techniques or in wind-pollinated isolated blocks. Eighty-two restriction fragment length polymorphism (RFLP) markers were used to examine samples of random mated, hand-pollinated BSSS(R) and BSCB1(R) maize populations to find out whether their genotypic proportions conformed to predicted outcomes of random mating. The majority of loci conformed to expectations for Hardy-Weinberg equilibrium (HWE). Excess homozygosity was observed at 87% of the loci where the null hypothesis of HWE was rejected ...


Response To Selection And Changes In Genetic Parameters For 13 Plant And Ear Traits In Two Maize Recurrent Selection Programs, J. F. Holthaus, K. R. Lamkey 2017 Holden's Foundation Seeds, Inc.

Response To Selection And Changes In Genetic Parameters For 13 Plant And Ear Traits In Two Maize Recurrent Selection Programs, J. F. Holthaus, K. R. Lamkey

Kendall R Lamkey

Recurrent selection is a cyclical breeding procedure that focuses on improving the mean performance of a population by increasing the frequency of favorable alleles and maintaining adequate genetic variability for continued selection response. The Iowa Stiff Stalk Synthetic (BSSS) maize (Zea mavs L.) population has undergone continuous recurrent selection for more than 50 years as the base population for two independent selection programs. This study was designed to estimate the mean performance and important genetic parameters in BSSS before and after seven cycles of half- sib (I IS) progeny selection, six cycles of Srprogeny selection, and 11 cycles of reciprocal ...


Fifty Years Of Recurrent Selection In The Iowa Stiff Stalk Synthetic Maize Population, K. R. Lamkey 2017 U.S. Department of Agriculture

Fifty Years Of Recurrent Selection In The Iowa Stiff Stalk Synthetic Maize Population, K. R. Lamkey

Kendall R Lamkey

Recurrent selection is a breeding procedure designed to increase the frequency of favorable alleles in a population. Increasing the frequency of favorable alleles will increase the probability of obtaining surerior inbred line.s for use in hybrids. The Iowa Stiff Stalk Synthetic (BSSS) maize (£ea mays I..) population has been involved in continuous recurrent selection since 1939. Thirteen cycles of selection have been completed . The first seven cycles were half-sib selection using the double-cross lowa 13 as a tester. After completion of seven cycles of half-sih selection, the population was renamed BSU and six cycles of S2-progeny selection were completed ...


Evaluation Of A Modified Reciprocal Recurrent Selection Procedure For Maize Improvement, W. A. Russell, D. J. Blackburn, Kendall R. Lamkey 2017 Iowa State University

Evaluation Of A Modified Reciprocal Recurrent Selection Procedure For Maize Improvement, W. A. Russell, D. J. Blackburn, Kendall R. Lamkey

Kendall R Lamkey

Reciprocal recurrent selection in maize (:Zea mays L.) has been ve1y successful in improving yields of crosses of two populations wherein each population has been used as a tester for the other. A modification of the procedure was suggested that uses two inbred lines as testers instead of the populations. The purpose of our research was to compare the two procedures for progress achieved after three cycles of recurrent selection. The populations were BS21 and BS22 Synthetics used in a reciprocal recurrent selection program (BS21R x BS22R). For the modified procedure, inbred A632 was the tester for BS21, [BS21(A632Hl ...


Population Genetics Of Increased Hybrid Performance Between Two Maize Populations Under Reciprocal Recurrent Selection, J. A. Labate, K. R. Lamkey, M. Lee, W. L. Woodman 2017 Iowa State University

Population Genetics Of Increased Hybrid Performance Between Two Maize Populations Under Reciprocal Recurrent Selection, J. A. Labate, K. R. Lamkey, M. Lee, W. L. Woodman

Kendall R Lamkey

Heterosis, the superiority in one or more characteristics of crossbred organisms relative to their inbred parents, is the basis of the modern cultivars utilized in maize (Zed mays L.). Heterosis is of interest in nondomesticated species due to its relevance to the question "how much polymorphism is maintained in natural populations due to selection?" (Berger, 1976). For maize and certain other domesticated species that employ inbred lines to produce commercial hybrids, knowledge of the mechanisms of gene action producing heterosis could contribute to advances in breeding techniques.


A Screen For Arabidopsis Thalianamutants With Altered Susceptibility To Heterodera Schachtii, T. J. Baum, M. J. E. Wubben II, K. A. Hardy, H. Su, S. R. Rodermel 2017 Iowa State University

A Screen For Arabidopsis Thalianamutants With Altered Susceptibility To Heterodera Schachtii, T. J. Baum, M. J. E. Wubben Ii, K. A. Hardy, H. Su, S. R. Rodermel

Thomas Baum

Genetic approaches are a powerful means to elucidate plant-pathogen interactions. An in vitro screening protocol was developed to identify Arabidopsis thaliana mutants with altered susceptibility to Heterodera schachtii, the sugar beet cyst nematode. In an initial screen of approximately 5,200 ethyl methanesulfonate-generated mutant plants, two stable mutations were identified. Both mutant lines were backcrossed and were found to harbor single recessive mutant alleles. Mutant line 2-4-6 shows an approximately two-fold increase in sedentary and developing nematodes, while mutant line 10-5-2 exhibits a significant decrease in susceptibility that manifests itself only after nematodes become sedentary. Analyses of progeny from crosses ...


Isolation Of Beta-1,4-Endoglucanase Genes From Globodera Tabacumand Their Expression During Parasitism, M. Goellner, G. Smant, J. M. De Boer, T. J. Baum, E. L. Davis 2017 North Carolina State University

Isolation Of Beta-1,4-Endoglucanase Genes From Globodera Tabacumand Their Expression During Parasitism, M. Goellner, G. Smant, J. M. De Boer, T. J. Baum, E. L. Davis

Thomas Baum

Two beta-1,4-endoglucanase (EGase) cDNAs were isolated from Globodera tabacum, the tobacco cyst nematode, and have been designated as GT-eng-1 and GT-eng-2. GT-eng-1 and GT-eng-2 encode precursor proteins with a predicted secretion signal sequence, cellulolytic catalytic domain, and a linker domain. The protein product GT-ENG-1 contains an additional 95 amino acid carboxy terminal sequence with strong similarity to type II cellulose binding domains. Riboprobes and polyclonal antibodies raised to recombinant cyst nematode EGases were used to follow expression patterns of EGase transcripts and proteins throughout the nematode life cycle. EGase transcripts and proteins were specifically detected within the subventral esophageal ...


Effects Of Zinc Fertilization Of Corn On Hatching Of Heterodera Glycines In Soil, J. E. Behm, G. L. Tylka, T. L. Niblack, W. J. Wiebold, P. A. Donald 2017 Iowa State University

Effects Of Zinc Fertilization Of Corn On Hatching Of Heterodera Glycines In Soil, J. E. Behm, G. L. Tylka, T. L. Niblack, W. J. Wiebold, P. A. Donald

Gregory Tylka

Experiments were conducted to determine the effects of zinc fertilizers on hatching and soil population densities of Heterodera glycines. In vitro egg hatching in solutions of reagent-grade zinc sulfate and zinc chloride and fertilizer-grade zinc sulfate was significantly greater than hatching in deionized water, whereas zinc chelate fertilizer significantly inhibited egg hatching relative to deionized water. In greenhouse experiments, no differences in cumulative percentage egg hatch were detected in soil naturally infested with H. glycines amended with fertilizer-grade zinc sulfate and zinc chelate at rates equivalent to 0, 1.12, 11.2, and 112 kg Zn/ha and subsequently planted ...


The Soybean Rhg1 Locus For Resistance To The Soybean Cyst Nematode Heterodera Glycines Regulates The Expression Of A Large Number Of Stress- And Defense-Related Genes In Degenerating Feeding Cells, Pramod Kaitheri Kandoth, Nagabhushana Ithal, Justin Recknor, Tom Maier, Dan Nettleton, Thomas J. Baum, Melissa G. Mitchum 2017 University of Missouri

The Soybean Rhg1 Locus For Resistance To The Soybean Cyst Nematode Heterodera Glycines Regulates The Expression Of A Large Number Of Stress- And Defense-Related Genes In Degenerating Feeding Cells, Pramod Kaitheri Kandoth, Nagabhushana Ithal, Justin Recknor, Tom Maier, Dan Nettleton, Thomas J. Baum, Melissa G. Mitchum

Thomas Baum

To gain new insights into the mechanism of soybean (Glycine max) resistance to the soybean cyst nematode (Heterodera glycines), we compared gene expression profiles of developing syncytia in soybean near-isogenic lines differing at Rhg1 (for resistance to Heterodera glycines), a major quantitative trait locus for resistance, by coupling laser capture microdissection with microarray analysis. Gene expression profiling revealed that 1,447 genes were differentially expressed between the two lines. Of these, 241 (16.8%) were stress- and defense-related genes. Several stress-related genes were up-regulated in the resistant line, including those encoding homologs of enzymes that lead to increased levels of ...


The Novel Cyst Nematode Effector Protein 19c07 Interacts With The Arabidopsis Auxin Influx Transporter Lax3 To Control Feeding Site Development, Chris Lee, Demosthenis Chronis, Charlotte Kenning, Benjamin Peret, Tarek Hewezi, Eric L. Davis, Thomas J. Baum, Richard Hussey, Malcolm Bennett, Melissa G. Mitchum 2017 University of Missouri

The Novel Cyst Nematode Effector Protein 19c07 Interacts With The Arabidopsis Auxin Influx Transporter Lax3 To Control Feeding Site Development, Chris Lee, Demosthenis Chronis, Charlotte Kenning, Benjamin Peret, Tarek Hewezi, Eric L. Davis, Thomas J. Baum, Richard Hussey, Malcolm Bennett, Melissa G. Mitchum

Thomas Baum

Plant-parasitic cyst nematodes penetrate plant roots and transform cells near the vasculature into specialized feeding sites called syncytia. Syncytia form by incorporating neighboring cells into a single fused cell by cell wall dissolution. This process is initiated via injection of esophageal gland cell effector proteins from the nematode stylet into the host cell. Once inside the cell, these proteins may interact with host proteins that regulate the phytohormone auxin, as cellular concentrations of auxin increase in developing syncytia. Soybean cyst nematode (Heterodera glycines) Hg19C07 is a novel effector protein expressed specifically in the dorsal gland cell during nematode parasitism. Here ...


Arabidopsis Spermidine Synthase Is Targeted By An Effector Protein Of The Cyst Nematode Heterodera Schachtii, Tarek Hewezi, Peter J. Howe, Tom R. Maier, Richard S. Hussey, Melissa G. Mitchum, Eric L. Davis, Thomas J. Baum 2017 Iowa State University

Arabidopsis Spermidine Synthase Is Targeted By An Effector Protein Of The Cyst Nematode Heterodera Schachtii, Tarek Hewezi, Peter J. Howe, Tom R. Maier, Richard S. Hussey, Melissa G. Mitchum, Eric L. Davis, Thomas J. Baum

Thomas Baum

Cyst nematodes are sedentary plant parasites that cause dramatic cellular changes in the plant root to form feeding cells, so-called syncytia. 10A06 is a cyst nematode secretory protein that is most likely secreted as an effector into the developing syncytia during early plant parasitism. A homolog of the uncharacterized soybean cyst nematode (Heterodera glycines), 10A06 gene was cloned from the sugar beet cyst nematode (Heterodera schachtii), which is able to infect Arabidopsis (Arabidopsis thaliana). Constitutive expression of 10A06 in Arabidopsis affected plant morphology and increased susceptibility to H. schachtii as well as to other plant pathogens. Using yeast two-hybrid assays ...


Eight Nonhost Weed Species Of Heterodera Glycines In Iowa, A. T. S. Wong, G. L. Tylka 2017 Iowa State University

Eight Nonhost Weed Species Of Heterodera Glycines In Iowa, A. T. S. Wong, G. L. Tylka

Gregory Tylka

The ability of the soybean cyst nematode (Heterodera glycines) to reproduce on eight weed species commonly occurring in Iowa was evaluated in greenhouse and field microplot experiments. Population densities of the nematode increased on H. g/ycines-susceptible soybean but not on H. g/ycines-resistant soybean, Canada thistle, cocklebur, eastern black nightshade, giant foxtail, lambsquarters, redroot pigweed, velvetleaf, and wild sunflower. All of the weeds evaluated were nonhosts of this H. glycines race 3 population.


Genomic And Physiological Approaches To Improve Drought Tolerance In Soybean, Avjinder Kaler 2017 University of Arkansas, Fayetteville

Genomic And Physiological Approaches To Improve Drought Tolerance In Soybean, Avjinder Kaler

Theses and Dissertations

Drought stress is a major global constraint for crop production, and improving crop tolerance to drought is of critical importance. Direct selection of drought tolerance among genotypes for yield is limited because of low heritability, polygenic control, epistasis effects, and genotype by environment interactions. Crop physiology can play a major role for improving drought tolerance through the identification of traits associated with drought tolerance that can be used as indirect selection criteria in a breeding program. Carbon isotope ratio (δ13C, associated with water use efficiency), oxygen isotope ratio (δ18O, associated with transpiration), canopy temperature (CT), canopy wilting, and canopy coverage ...


Differentially Regulated Orthologs In Sorghum And The Subgenomes Of Maize, Yang Zhang, Daniel W. Ngu, Daniel Carvalho, Zhikai Liang, Yumou Qiu, Rebecca Roston, James C. Schnable 2017 University of Nebraska - Lincoln

Differentially Regulated Orthologs In Sorghum And The Subgenomes Of Maize, Yang Zhang, Daniel W. Ngu, Daniel Carvalho, Zhikai Liang, Yumou Qiu, Rebecca Roston, James C. Schnable

Faculty Publications from the Center for Plant Science Innovation

Identifying interspecies changes in gene regulation, one of the two primary sources of phenotypic variation, is challenging on a genome-wide scale. The use of paired time-course data on cold-responsive gene expression in maize (Zea mays) and sorghum (Sorghum bicolor) allowed us to identify differentially regulated orthologs. While the majority of cold-responsive transcriptional regulation of conserved gene pairs is species specific, the initial transcriptional responses to cold appear to be more conserved than later responses. In maize, the promoters of genes with conserved transcriptional responses to cold tend to contain more micrococcal nuclease hypersensitive sites in their promoters, a proxy for ...


Dissecting The Genetic Basis Of Salt Tolerance In Rice (Oryza Sativa), Malachy Thomas Campbell 2017 University of Nebraska-Lincoln

Dissecting The Genetic Basis Of Salt Tolerance In Rice (Oryza Sativa), Malachy Thomas Campbell

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Excessive salt is a major factor limiting crop productivity. Rice is an important food crop worldwide, and provides a major source of calories for billions of people in tropical and subtropical developing countries. In many regions throughout Southeast Asia, rice is grown in low-lying coastal regions, which are prone to ingress by seawater. Rice is highly sensitive to salt stress, with mild salinity resulting in large reductions in yield. Improving salt tolerance in rice is essential for ensuring food security for many individuals throughput the developing world.

In this work, the overall goals were to characterize a diverse collection of ...


Photosynthesis And Shoot Health Of Five Birch And Four Alder Taxa After Drought And Flooding, William R. Graves, Mark A. Kroggel, Mark P. Widrlechner 2017 Iowa State University

Photosynthesis And Shoot Health Of Five Birch And Four Alder Taxa After Drought And Flooding, William R. Graves, Mark A. Kroggel, Mark P. Widrlechner

William R Graves

Selection of under-used taxa of birches (Betula L.) and alders (Alnus Miller) for use in managed landscapes can be guided by information on their responses to moisture extremes in the root zone. Our objective was to compare the photosynthesis, leaf surface area, and subjective health ratings of eight relatively obscure birches and alders when treated with drought and flooding in a greenhouse. We also treated ‘Whitespire Sr.’ birch (Betula populifolia) to demonstrate responses of a cultivar common in the nursery trade. Plants used as controls were irrigated daily, whereas pots of flooded plants were immersed. All water was withheld from ...


Phenotypic And Genotypic Diversity Of Eastern Leatherwood In Five Populations That Span Its Geographic Distribution, Bryan J. Peterson, William R. Graves, Jyotsna Sharma 2017 Iowa State University

Phenotypic And Genotypic Diversity Of Eastern Leatherwood In Five Populations That Span Its Geographic Distribution, Bryan J. Peterson, William R. Graves, Jyotsna Sharma

William R Graves

Knowledge of variation among populations is important for making decisions about conservation of rare, threatened or endangered taxa. We investigated variation within and among five populations ofDirca palustris L. an understory shrub with a sporadic distribution and life-history traits that led us to predict strong phenotypic and genetic differentiation characteristic of historically limited gene flow. Populations sampled in Florida, Alabama, Illinois, Wisconsin and North Dakota spanned the geographic distribution of the species. Phenotypic traits differed among populations, and many traits correlated with latitude and environmental characteristics of the five sites. Principal components (PC) analysis showed that the first three PCs ...


Phenotypic Variation And Genetic Purity Of The Original 'Prime-Jim®' X 'Arapaho' Population, Loren M. Luther 2017 University of Arkansas

Phenotypic Variation And Genetic Purity Of The Original 'Prime-Jim®' X 'Arapaho' Population, Loren M. Luther

Horticulture Undergraduate Honors Theses

In 2013, Castro et al., produced the first linkage map for primocane-fruiting blackberries using the cross ‘Prime-Jim®’ x ‘Arapaho.’ This mapping population has been maintained since the original experiment with the hopes of conducting future studies. Further research was determined to be needed on the population to better characterize additional phenotypic traits, and since nine years had passed since the seedlings were established, there was a need to assess the continued genetic purity of the population using molecular methods. Phenotypic data was collected to analyze the variation of the population including soluble solids content, titratable acidity, average weight, shape, and ...


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