Plant Pathology Commons^™

Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant

Doctoral Dissertations

Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …

Identification Of Quantitative Trait Loci (Qtls) For Resistance To Bacterial Leaf Streak: Xanthomonas Translucens Using Qtl And Association Mapping In Three Populations Of Soft Red Winter Wheat, Benjamin Tyler Meritt

LSU Doctoral Dissertations

Bacterial leaf streak (BLS) and black chaff, caused by Xanthomonas translucens pv. undulosa (Xtu), can be a very destructive disease of wheat, especially in the warmer, wetter areas of the Southeastern U.S. Yield losses of up to 40 percent have been recorded in some cases in southern wheat growing regions. With no effective agronomic or chemical method of disease control, identification of genetic resistance is seen as a promising solution. Three soft red winter wheat populations (GAWN, ARK-SNP, and AGS 2060- AGS 2035 DH) representative of soft red winter wheat germplasm in the southeastern U.S. developed by …

Primary Industries Development Research Highlights 2021, Department Of Primary Industries And Regional Development, Tim Scanlon

Books & book chapters

The Primary Industries Development Research Highlights 2021 showcases the breadth and depth of the Department of Primary Industries and Regional Development’s research and development activities over the past several years.

Stories featured in Research Highlights 2021 stem from about 60 (of 140) current and recently-completed projects undertaken by the Department of Primary Industries and Regional Development’s (DPIRD) 1100 scientists, technical experts and economists throughout the State.

Explore our Research Highlights 2021.

The publication demonstrates the innovative and applicable research that DPIRD and its collaborators and investment partners deliver to Western Australia.

Download the Research Highlights 2021 here. Alternatively, …

Genetic Variability In Fusarium Oxysporum F. Sp. Vasinfectum Causing Damping-Off Of Cotton (Gossypium Barbadense L.) Seedlings [Research Note], Reda Helmy Sammour, Salah Abdel Moemen, Eman Elagamy

The Philippine Agricultural Scientist

The genetic variability of Fusarium oxysporum f. sp. vasinfectum isolates from Gossypium barbadense L. seedlings were assessed using pathogenicity, mycelial compatibility, and RAPD analyses. The results showed that the disease incidence percentages and compatibility percentages considerably varied, extending from 33.2 to 86.6 % and 6 to 60 %, respectively in North Egypt and from 33.3 to 66.6 % and 0.0 to 20% in South Egypt. It also showed that the isolates ISO-8 and ISO-19 had the lowest disease incidence (33.2%) as compared with isolate ISO-5 (86.6%). Results of the mycelial compatibility had a reversible relationship with disease incidence percentage. Cluster …

Temperature Regulation Of Plant Hormone Signaling During Stress And Development, Christian Castroverde, Damaris Dina

Biology Faculty Publications

Global climate change has broad-ranging impacts on the natural environment and human civilization. Increasing average temperatures along with more frequent heat waves collectively have negative effects on cultivated crops in agricultural sectors and wild species in natural ecosystems. These aberrantly hot temperatures, together with cold stress, represent major abiotic stresses to plants. Molecular and physiological responses to high and low temperatures are intricately linked to the regulation of important plant hormones. In this review, we shall highlight our current understanding of how changing temperatures regulate plant hormone pathways during immunity, stress responses and development. This article will present an overview …

Analysis Of Symptom Expressions And Transmission Rates Caused By The Plant Pathogen Phytophthora Ramorum On Native Chaparral Plants From The Genus Arctostaphylos, Bharati Gaonker

Natural Sciences and Mathematics | Biological Sciences Master's Theses

Phytophthora ramorum is the causal agent of Sudden Oak death (SOD), ramorum dieback and ramorum leaf blight which affect both forest environments and nurseries. This oomycete pathogen has had a huge economic impact on the nursery and lumber industry. Forests in California have experienced substantial mortality of oaks affecting the forest dynamics and diversity. Our research investigates four native species and two ornamental cultivars of plants, which belong to the genus Arctostaphylos (manzanita) and are considered to be new hosts for P. ramorum in the chaparral ecosystem of California. Symptom expression and transmission rates were analyzed on Arctostaphylos glauca, …

Population Structure And Reproductive Biology Of Monilinia Vaccinii-Corymbosi (Reade) Honey In Lowbush Blueberry In Maine, Katherine A. Ashley

Electronic Theses and Dissertations

Lowbush blueberry, Vaccinium angustifolium Aiton, is both an economically and culturally important crop in Maine, being one of the few endemic crops to North America. The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease and is a significant pathogen of both highbush (Vaccinium corymbosum) and lowbush blueberries. While impacts of this disease are not regularly documented, it is estimated that 30-50% of the yield in an unmanaged field can be lost because of Mvc. This disease is typically managed with fungicides or burning of the field during years when the field is pruned, however, the impacts to the …

Genetic And Biochemical Characterization Of Ergot Alkaloid Synthesizing Fungi And Their Symbionts, Matthew Duane Maust

Graduate Theses, Dissertations, and Problem Reports

Ergot alkaloids are fungal tryptophan derived toxins which affect mammalian circulation and neurotransmission. These compounds are biosynthesized by a conserved genetic pathway, known as the ergot alkaloid synthesis (EAS) pathway by fungi belonging to the ascomycete families Trichocomaceae and Clavicipitaceae. Several Ipomoea species and related plants in the morning glory family harbor vertically transmitted symbiotic fungi in the genus Periglandula, also members of Clavicipitaceae, that produce ergot alkaloids. Metabolomic analysis of seeds identified a previously uncharacterized glycoside form of the pharmaceutically important ergot alkaloid, ergonovine. Several species belonging to the fungal genus Metarhizium have recently been shown to have the …

Tal Effector-Nucleotide Targeter (Tale-Nt) 2.0: Tools For Tal Effector Design And Target Prediction, Erin L. Doyle, Nicholas J. Booher, Daniel S. Standage, Daniel F. Voytas, Volker P. Brendel, John K. Vandyk, Adam J. Bogdanove

Nicholas J. Booher

Transcription activator-like (TAL) effectors are repeat-containing proteins used by plant pathogenic bacteria to manipulate host gene expression. Repeats are polymorphic and individually specify single nucleotides in the DNA target, with some degeneracy. A TAL effector-nucleotide binding code that links repeat type to specified nucleotide enables prediction of genomic binding sites for TAL effectors and customization of TAL effectors for use in DNA targeting, in particular as custom transcription factors for engineered gene regulation and as site-specific nucleases for genome editing. We have developed a suite of web-based tools called TAL Effector-Nucleotide Targeter 2.0 (TALE-NT 2.0;https://boglab.plp.iastate.edu/) that enables design …

Sequence Analysis Of The Ren1 Genomic Region From The Grapevine ‘Kishmish Vatkana’, Dani Joseph

MSU Graduate Theses

The REN1 region of the grapevine ‘Kishmish Vatkana’ was mapped as the locus that confers resistance to the economically important disease, grape powdery mildew. The purpose of this work was to extend the nucleotide sequence information of this region. By sequencing a heretofore unknown bacterial artificial chromosome clone, the sequence information of this region was extended by 46,890 nucleotides. Sequencing was performed using the third-generation sequencing method, named Oxford Nanopore Technology (ONT). In order to improve the accuracy of the sequence data, a modified ONT library preparation method was developed. ONT sequencing of a library prepared with the modified protocol …

Mapping A New Disease Resistance Locus In An F1 Progeny Derived From Two Grape Wild Relatives, Gaurab Bhattarai

MSU Graduate Theses

Linkage maps and quantitative trait loci (QTL) analysis have become essential tools for the positional cloning of agronomically important genes and for marker-assisted breeding. In this study, two North American grape species, Vitis rupestris and Vitis riparia, and their 294 F₁ progeny were used to construct parental linkage maps and to perform QTL analysis for downy mildew resistance. Single nucleotide polymorphism (SNP) discovery was accomplished using genotyping-by-sequencing (GBS) and resulted in 348,888 SNPs. Of these, 11,063 informative SNP markers (3.17% of the original SNP dataset) were derived after filtering for various quality parameters and missing data. A two-way …

Genetic Regulation Of The Elicitation Of Glyceollin Biosynthesis In Soybean, Md. Asraful Jahan

Graduate Theses, Dissertations, and Problem Reports

Glyceollin phytoalexins are the pathogen-elicited defense metabolites that belong to the isoflavonoid family of molecules of soybean (Glycine max L. Merr). Phytophthora root and stem rot of soybean caused by Phytophthora sojae is a destructive disease throughout the soybean-growing regions worldwide causing devastating economic damages (globally $1-2 billion and over $250 million in the USA) every year. Engineering soybean plants that produce higher levels of glyceollins could confer resistance against this pathogen. Glyceollins also show anticancer and neuroprotective activities in mammals, therefore they are important for agriculture and medical research. Firstly, we were interested in understanding how biotic and …

Breeding For Resistance In California Strawberry To Verticillium Dahliae, Zachary Christman

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

This article focuses on breeding resistant strawberries to the fungus Verticillium dahliae, common name Verticillium wilt. This is a serious fungal disease that can result in a loss of 50% or more of a strawberry harvest when grown in infested soil. The main goal is to provide an example of how a cultivar can be made more resistant to a plant pathogen with the use of plant breeding methods.

Since 1930 the University of California, Davis, has been developing strawberry cultivars that are adapted to the agricultural industry and regional farms. Developing cultivars that require fewer inputs are of …

A New Toolset For Protein Expression And Subcellular Localization Studies In Citrus And Its Application To Citrus Tristeza Virus Proteins, Amit Levy, Choaa El-Mochtar, Chunxia Wang, Michael M. Goodin, Vladimir Orbovic

Plant Pathology Faculty Publications

Background

Transient gene expression is a powerful tool to study gene function in plants. In citrus, Agrobacterium transformation is the method of choice for transient expression studies, but this method does not work efficiently with many gene constructs, and there is a need for a more robust transient expression system in citrus leaves. Biolistic particle delivery is an alternative to Agrobacterium transformation, and in some plants, such as Arabidopsis, gives higher transformation rates in leaf tissues than Agrobacterium.

Results

Here we describe an improved method for gene expression in epidermal cells of citrus leaves, using the Bio-Rad Helios gene-gun. …

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 …

Chromosome-End Knockoff Strategy To Reshape Alkaloid Profiles Of A Fungal Endophyte, Simona Florea, Timothy D. Phillips, Daniel G. Panaccione, Mark L. Farman, Christopher L. Schardl

Plant Pathology Faculty Publications

Molecular genetic techniques to precisely eliminate genes in asexual filamentous fungi require the introduction of a marker gene into the target genome. We developed a novel strategy to eliminate genes or gene clusters located in subterminal regions of chromosomes, and then eliminate the marker gene and vector backbone used in the transformation procedure. Because many toxin gene clusters are subterminal, this method is particularly suited to generating nontoxic fungal strains. We tested this technique on Epichloë coenophiala, a seed-transmissible symbiotic fungus (endophyte) of the important forage grass, tall fescue (Lolium arundinaceum). The endophyte is necessary for maximal …

Calmodulin-Like Protein 38: A Component Of Ribonucleoprotein Particles During Hypoxic Stress Responses In Arabidopsis, Ansul Lokdarshi

Doctoral Dissertations

Waterlogging stress leads to a crisis in energy metabolism and the accumulation of toxic metabolites due to the hypoxic and/or anoxic environment associated with this condition. To respond and adapt to this situation, higher plants employ an integrated genetic program that leads to the induction of anaerobic response polypeptide genes that encode metabolic and signaling proteins involved in altering metabolic flow and other adaptive responses. The study presented here shows that the Arabidopsis thaliana calmodulin-like protein CML38 is calcium sensor protein that serves as a member of the core anaerobic response gene family and is involved in modulating the survival …

Population Structure Of Late Blight (Phytophthora Infestans) In Colombia And Ecuador And Downy Mildew (Peronospora Farinosa F. Sp. Spinaciae) On Spinach In Arizona And California, Rebecca Marie Lyon

Masters Theses

In this study, Phytophthora infestans and Peronospora farinosa f. sp. spinaciae populations were analyzed using single nucleotide polymorphisms (SNPs). In Ecuador and Colombia, Phytophthora infestans causes significant damage to potato and tomato and the epidemiology is known to be highly clonal. Our objective was to measure population structure within the context of this clonal epidemiology using both synonymous and nonsynonymous markers. Candidate SNP sites were selected by comparing the draft genomes of the Ecuadorian isolates EC1-3527 and EC1-3626. Genotypes were assessed directly from infected tissue using a targeted sequencing approach. A total of 54 polymorphic sites were assessed in 93 …

Characterization Of A Novel Clade Of Transporters In Phytophthora, Stephanie Padula, Paul F. Morris Dr, Howard Casey Cromwell Dr., Menaka Ariyaratne, Andrew Wagner

Honors Projects

The oomycete Phytophthora parasitica has a worldwide distribution and is an economically important pathogen of more than 100 species⁴. RNA-seq analysis showed that one gene, PPTG_16698 has the 5^th highest level of expression of all transport proteins in the zoospore stage, and is highly conserved throughout Phytophthora species. This project attempts to characterize the important biological role that PPTG_16698 plays in P. parasitica and other oomycetes. Three strategies have been implemented to accomplish this goal: growth analysis by heterologous expression in yeast, metabolite analysis in yeast, and construction of a GFP fusion protein to enable localization of …

Tal Effector-Nucleotide Targeter (Tale-Nt) 2.0: Tools For Tal Effector Design And Target Prediction, Erin L. Doyle, Nicholas J. Booher, Daniel S. Standage, Daniel F. Voytas, Volker P. Brendel, John K. Vandyk, Adam J. Bogdanove

John K. VanDyk

Transcription activator-like (TAL) effectors are repeat-containing proteins used by plant pathogenic bacteria to manipulate host gene expression. Repeats are polymorphic and individually specify single nucleotides in the DNA target, with some degeneracy. A TAL effector-nucleotide binding code that links repeat type to specified nucleotide enables prediction of genomic binding sites for TAL effectors and customization of TAL effectors for use in DNA targeting, in particular as custom transcription factors for engineered gene regulation and as site-specific nucleases for genome editing. We have developed a suite of web-based tools called TAL Effector-Nucleotide Targeter 2.0 (TALE-NT 2.0;https://boglab.plp.iastate.edu/) that enables design of custom …

Gata-Family Transcription Factors In Magnaporthe Oryzae, Cristian F. Quispe

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

The filamentous fungus, Magnaporthe oryzae, responsible for blast rice disease, destroys around 10-30% of the rice crop annually. Infection begins when the specialized infection structure, the appressorium, generates enormous internal turgor pressure through the accumulation of glycerol. This turgor acts on a penetration peg emerging at the base of the cell, causing it to breach the leaf surface allowing its infection.

The enzyme trehalose-6- phosphate synthase (Tps1) is a central regulator of the transition from appressorium development to infectious hyphal growth. In the first chapter we show that initiation of rice blast disease requires a regulatory mechanism involving an …

Evaluation Of Genetic Diversity Of Flowering Dogwood (Cornus Florida L.) In The Eastern United States Using Microsatellites., Denita Hadziabdic

Doctoral Dissertations

Flowering dogwood (Cornus florida L.) populations have experienced severe declines caused by dogwood anthracnose in the past three decades. Mortality has ranged from 48 to 98%, raising the concern that genetic diversity of this native tree has been reduced significantly. Microsatellite data were used to evaluate the level and distribution of genetic variation throughout much of the native range of the tree. In the first conducted study, we found that genetic variation in areas affected by anthracnose was as high as or higher than areas without die-offs. We found evidence of four widespread, spatially contiguous genetic clusters. However, there was …

Sheep Updates 2006 - Part 2, Darryl Smith, Kathryn Kemper, David Rutley, R. R. Woolaston, D. J. Brown, K. D. Atkins, A. E. Casey, A. J. Ball, David Hopkins, David Stanley, Leonie Martin, Arthur Gilmour, Remy Van De Ven, Geoff Duddy, Steve Semple, David Kessell, Andrew Thompson

Sheep Updates

This session covers six papers from different authors:

GENETICS

1. Novel selection traits - what are the possible side effects?, Darryl Smith, Kathryn Kemper, South Australian Research and Development Institute, David Rutley, University of Adelaide.

2. Genetic Changes in the Australian Merino since 1900, Sheep Genetics Australia Technical Committee, R.R. Woolaston Pullenvale, Queensland, D.J. Brown, Animal Genetics and Breeding Unit*, University of New England, K.D. Atkins, A.E. Casey, NSW Department of Primary Industries, A.J. Ball, Meat and Livestock Australia, University of New England

3. Influence of Sire Growth Estimated Breeding Value (EBV0 on Progeny Growth, David Hopkins, David Stanley, Leonie …