Plant Pathology Commons^™

Epistatic Interaction Between Rhg1‑A And Rhg2 In Pi 90763 Confers Resistance To Virulent Soybean Cyst Nematode Populations, Pawan Basnet, Clinton G. Meinhardt, Mariola Usovsky, Jason D. Gillman, Trupti Joshi, Qijian Song, Brian Diers, Melissa G. Mitchum, Andrew M. Scaboo

Biomedical Sciences

Key message

An epistatic interaction between SCN resistance loci rhg1-a and rhg2 in PI 90763 imparts resistance against virulent SCN populations which can be employed to diversify SCN resistance in soybean cultivars.

Abstract

With more than 95% of the $46.1B soybean market dominated by a single type of genetic resistance, breeding for soybean cyst nematode (SCN)-resistant soybean that can effectively combat the widespread increase in virulent SCN populations presents a significant challenge. Rhg genes (for Resistance to Heterodera glycines) play a key role in resistance to SCN; however, their deployment beyond the use of the rhg1-b allele has been …

Plectus Of The Prairie: A Case Study Of Taxonomic Resolution From A Nematode Biodiversity Survey, Abigail Borgmeier, Kaitlin Gattoni, Timothy Harris, Rebecca Higgins, Peter Mullin, Dorota Porazinska, Kirsten S. Powers, David A. Wedin, Tom Powers

Department of Plant Pathology: Faculty Publications

Taxonomic resolution is a critical component of biodiversity assessments. In this case study, we examined a single taxon within a larger study of nematode diversity to evaluate the taxonomic resolution of different diversity assessment methods. The selected taxon was the microbial-feeding genus Plectus, a group considered to include multiple cosmopolitan species. The methods included a morphological evaluation by light microscopy, Sanger sequencing of PCR amplicons of COI and 18S gene regions, and 18S metabarcoding sequencing. The study sites were 15 remnant tallgrass prairie plots in eastern Nebraska. In the morphological analysis, we observed two basic morphotypes, a short-tailed form …

Association Mapping Across A Multitude Of Traits Collected In Diverse Environments In Maize, Ravi V. Mural, Guangchao Sun, Marcin Grzybowski, Michael C. Tross, Hongyu Jin, Christine Smith, Linsey Newton, Carson M. Andorf, Margaret R. Woodhouse, Addie M. Thompson, Brandi Sigmon, James C. Schnable

Center for Plant Science Innovation: Faculty Publications

Classical genetic studies have identified many cases of pleiotropy where mutations in individual genes alter many different phenotypes. Quantitative genetic studies of natural genetic variants frequently examine one or a few traits, limiting their potential to identify pleiotropic effects of natural genetic variants. Widely adopted community association panels have been employed by plant genetics communities to study the genetic basis of naturally occurring phenotypic variation in a wide range of traits. High-density genetic marker data—18M markers—from 2 partially overlapping maize association panels comprising 1,014 unique genotypes grown in field trials across at least 7 US states and scored for 162 …

Efficacy And Timing Of Application Of Fungicides, Biofungicides, Host-Plant Defense Inducers, And Fertilizer To Control Phytophthora Root Rot Of Flowering Dogwoods In Simulated Flooding Conditions In Container Production, Krishna Neupane, Bhawana Ghimire, Fulya Baysal-Gurel

Agricultural and Environmental Sciences Faculty Research

Phytophthora root rot caused by Phytophthora cinnamomi Rands is one of the major diseases of flowering dogwoods (Cornus florida L.). The severity of root rot disease increases when the plants are exposed to flooding conditions. A study was conducted to determine the efficacy and timing of application of different fungicides, biofungicides, host plant defense inducers, and fertilizer to manage Phytophthora root rot in month-old seedlings in simulated flooding events for 1-, 3-, and 7- days. Preventative treatments were drench applied 3 weeks and 1 week before flooding whereas curative treatments were applied 24 hrs. after flooding. Dogwood seedlings were inoculated …

Characterization Of Corynespora Cassiicola Resistance To The Quinone Outside Inhibitor Fungicides, Elucidation Of Fitness Parameters, And Defining Alternative Fungicide Product Strategies In Mississippi Soybean, Xiaopeng Wang

Theses and Dissertations

Target spot, caused by Corynespora cassiicola, is a common lower canopy disease of soybean in the southern United States. Given the recent resurgence of target spot and increasing reports of resistance to the quinone outside inhibitor (QoI) fungicide class within C. cassiicola, a survey of C. cassiicola from the Mississippi soybean production system was initiated in 2019 to determine the nature of its resistance mechanisms. A total of 819 monoconidial isolates were collected from 228 geographic field locations in 75 Mississippi counties. The molecular mechanism of resistance was determined using a PCR-RFLP analysis by comparing nucleotide sequences in …

Epidemiology And Impacts Of A Leaf Spot Disease In Veratrum Viride (Melanthiaceae), Leeah R. Sutton, Foster Levy

Undergraduate Honors Theses

Fungal phytopathogens can cause disease epidemics in crops, weeds, and
populations of native plants. To investigate the impact of a foliar phytopathogen on the native herbaceous species, Veratrum viride, a demographic and disease assessment was carried out on two high elevation grassy bald populations on Roan Mountain, Tennessee. A leaf spot disease impacted all plants in both populations, causing widespread premature senescence of leaves and stems. Disease severity increased over the course of the growing season. Based on host disease symptoms and fungal conidia morphology, Pseudocercosporella sublineolata was shown to be the causal pathogen. A study of herbarium specimens …

An In Vitro Approach To Identify Sources Of Resistance To Fusarium Wilt Caused By Fusarium Oxysporum F. Sp. Vasinfectum Race 4 In Domesticated Cotton, Stephen Parris

All Theses

Cotton lint produced by the plants Gossypium barbadense L. (pima cotton) and Gossypium hirsutum L. (upland cotton) is the world’s leading source of renewable textiles. The fibers of the cotton plant have been woven so intricately into our society that it would be hard to imagine life without their products. Cotton breeders must then not only continue to work to improve the quality of cotton fibers (fineness, strength, dyability, etc.) but also to improve the resilience of the plant against biotic and abiotic factors. Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) is an aggressive fungal pathogen, which causes Fusarium …

Identification Of Cytospora Species Isolated From Canker In Peach Trees In South Carolina, Stephen T. Baker

All Theses

In 2016, a survey was conducted into the causes of twig blight on peach (Prunus persica) in five orchards across South Carolina. From this survey, isolates from the fungal genus of Cytospora (Sordariomycetes, Diaporthales) were reported on peach, for the first time, within the state. Cytospora species are known to cause oozing cankers on a wide range of woody hosts leading to dieback, loss of limbs, and reduction in yield, prompting concern for important economic crops. Past methods of identification of Cytospora species have been confounded by indistinguishable morphology, overlapping host preference among species, and genetic sequencing …

Functional Characterization Of A Putative Alternative Oxidase In Sporisorium Reilianum F. Sp. Zeae., Emma A Lamb

College of Arts & Sciences Senior Theses

Sporisorium reilianum is a pathogenic basidiomycete fungus with two formae speciales, each capable of infecting corn (SRZ) or sorghum (SRS), respectively. This fungus is also a dimorphic variety, meaning it can switch between its haploid, yeast-like sporidia and diploid teliospore stages over the course of its life cycle (Schirawski). When S. reilianum is found in a haploid state and conditions are favorable, it will mate with a compatible non-self mating type to begin filamentous growth and proliferation in the plant host (Zhao). S. relianum, like most fungi, utilizes the four classical components of the electron transport chain to produce …

A Small Stem Assay For Chestnut Blight Resistance In Hybrid American Chestnut Trees, Evelyn Odle

Honors Theses

Cryphonectria parasitica (Murr.) Barr is the causal agent for the chestnut blight disease, which was brought to North America in the late 19th century on nursery stock from Japan (Anagnostakis 1987). A pandemic of chestnut blight lasted for the next half century, nearly wiping out all American chestnut trees (Castanea dentata Borkh.). Restoration works to restoring the American chestnut to its native range in North America’s canopy has been going on for the past century. The American Chestnut Foundation has strived to breed a resistant American chestnut by backcross breeding with Chinese species (C. mollissima Blume) since the 1980s. The …

Site-Specific Pest Management In Nebraska Corn And Soybean Production Systems, Zachary D. Rystrom

Doctor of Plant Health Program: Dissertations and Student Research

Site-specific management (SSM) is widely used by farm producers to fertilize their fields. However, whole field management is currently practiced in integrated pest management (IPM). Site-specific management and agricultural technology can improve IPM especially when precision application of inputs can reduce selection pressure on pest populations, benefit the environment, or save costs of inputs. There is potential for site-specific pest management (SSPM) where pests, or environments vary spatially, and recommended management practices can be applied with precision. Three case studies are evaluated for SSPM to be applied in Nebraska corn and soybean production systems including corn rootworm, preemergence herbicides, and …

Distribution And Genomic Diversity Of Pollen-Borne Viruses And Viroids At The Interface Of Peach And Wild Prunus Spp. In The Southeastern United States, Fabian Omar Rodriguez Bonilla

All Theses

Prunus necrotic ringspot virus (PNRSV), prune dwarf virus (PDV), and peach latent mosaic viroid (PLMVd) are important pollen-borne pathogens that affect peach orchards in the southeastern United States. My aim with this research is to identify potential sources of virus/viroid inoculum sources in the wild and determine pathogen movement and interactions between wild Prunus spp. and cultivars of peach (P. persica). In Chapter I, I review the literature on pollen borne viruses and viroids in peach. In Chapter II, I surveyed for these pathogens near peach production areas in South Carolina and Georgia, sampling from three endemic wild …

Evaluation Of Fenclorim Safener For Use In Rice With Group 15 Herbicides, Tristen Heath Avent

Graduate Theses and Dissertations

The development of herbicide resistance and the lack of effective herbicides to control problematic weeds has caused Arkansas rice (Oryza sativa L.) production to pursue alternative sites of action. Currently, very long-chain fatty acid elongase inhibitors are not labeled for U.S. rice production but have been widely used for Asian rice production systems. Previous research has demonstrated the utility of acetochlor and pyroxasulfone to provide in-season weed control for Arkansas rice production, but variable crop tolerance has been observed. Additionally, acetochlor at 1,260 g ai ha-1 elicited less rice injury when seeds were treated with a herbicide safener seed treatment …

Abiotic Disorders Of Tomatoes, Nick Volesky, Marion Murray, Sheriden M. Hansen, Maegen A. Lewis

All Current Publications

Monitoring tomato plants regularly from seedling to harvest allows for early detection of abnormal conditions. Although tomato plants can be attacked by a variety of living organisms (insects, mites, pathogens, vertebrates), nonliving (abiotic) conditions can cause just as much damage. Abiotic diseases in tomato plants can arise from nutrient deficiencies, temperature extremes, abnormal lighting, chemical application, changes in water uptake, mechanical damage, genetic mutations, and more. This guide will cover most of the abiotic disorders and diseases that can affect tomatoes in Utah.

Big Bud Disease In Tomatoes And Peppers, Claudia Nischwitz, Erin Petrizzo

All Current Publications

This fact sheet provides information on the symptoms of big bud on tomatoes and peppers. It reviews the disease cycle and recommendations on controlling beet leafhopper and managing big bud disease in Utah.

Genetic Diversity In Helianthus Annuus: Selective Breeding And Induced Mutagenesis, Dillon Holton

Thinking Matters Symposium

H. annuus, more commonly known as the sunflower, is a single species that has many different variations. Traits have been selectively bred for hundreds of years in order to produce a beautiful flower as well as essential agricultural products. Recently interest in the sunflower as a food and fuel crop has led to selective breeding of seeds that produce high yields of sunflower oil. To further push the limits of this plant's genome, researchers have used mutagenesis to force mutations in hopes of developing novel modifications that could increase yield. With the entire genome mapped, the goal for many research …

Marker-Trait Association Mapping Of Sorghum Mosaic Virus Resistance In Sugarcane, Chenie Zamora

LSU Master's Theses

Mosaic is a potentially devastating disease of sugarcane that had severe economic impact on Louisiana’s sugarcane industry in the 1920’s and has caused periodic problems ever since. The disease is vectored by migrating aphids that transmit Sugarcane mosaic virus (SCMV) and Sorghum mosaic virus (SrMV) in a non-persistent manner. Mosaic in Louisiana is currently caused by strains of SrMV. Mosaic has been controlled primarily by developing resistant cultivars. Recently, mosaic was detected in some near-commercial clones in the cultivar selection program. This prompted extensive screening of breeding program parent populations that detected infiltration of susceptibility and revealed the need for …

Development Of Alternative Materials And Strategies For Enhancing Rice Health, Jobelle S. Bruno

LSU Master's Theses

Bacterial panicle blight (BPB) and sheath blight (ShB) are economically important diseases of rice (Oryza sativa) in Louisiana and other rice-growing regions around the world. However, there are challenges in the current disease management practices for these diseases. Thus, the main goal of this study is to identify new materials and their application methods that effectively suppress BPB and ShB. To achieve this goal, we evaluated the effect of various materials and application methods against the rice diseases. In 2020 and 2021, various materials, such as ascorbic acid (AA), N-acetylcysteine, chitosan, the avirulent strain of Burkholderia glumae 257sh-1 …

Landscapes Are Cornerstones Of Sustainability Programs, Don Spence

Sustainability Conference

Typical American landscapes are not sustainable in an economic or biological framework. The essence of the idea of sustainable growth and development are centered on the idea that those activities are not degrading natural resources or that they are outstrip budgets. A significant piece of any sustainable management plan is tied to how we manage our landscapes, how we use plants; specifically, how much grass there is, and how many native plants there are. Sustainable landscapes should require less chemical and financial inputs, which in the end, saves money and increases the biological value of the land and creates a …

Two Magnaporthe Appressoria-Specific (Mas) Proteins, Momas3 And Momas5, Are Required For Suppressing Host Innate Immunity And Promoting Biotrophic Growth In Rice Cells, Ziwen Gong, Na Ning, Zhiqiang Li, Xin Xie, Richard Wilson, Wende Liu

Department of Plant Pathology: Faculty Publications

In the devastating rice blast fungus Magnaporthe oryzae, six Magnaporthe appressoria-specific (MAS) proteins are encoded by MoGAS1, MoGAS2 and MoMAS3–MoMAS6. MoGAS1 and MoGAS2 were previously characterized as M. oryzae virulence factors; however, the roles of the other four genes are unknown. Here, we found that, although the loss of any MAS gene did not affect appressorial formation or vegetative growth, ΔMomas3 and ΔMomas5 mutant strains (but not the others) were reduced in virulence on susceptible CO-39 rice seedlings. Focusing on ΔMomas3 and ΔMomas5 mutant strains, we found that they could penetrate …

Identification And Characterization Of Circular Rnas In Brassica Rapa In Response To Plasmodiophora Brassicae, Huishan Liu, Chinedu Charles Nwafor, Yinglan Piao, Xiaonan Li, Zongxiang Zhan, Zhongyun Piao

Center for Plant Science Innovation: Faculty Publications

Plasmodiophora brassicae is a soil-borne pathogen that attacks the roots of cruciferous plants and causes clubroot disease. CircRNAs are noncoding RNAs, widely existing in plant and animal species. Although knowledge of circRNAs has been updated continuously and rapidly, information about circRNAs in the regulation of clubroot disease resistance is extremely limited in Brassica rapa. Here, Chinese cabbage (BJN 222) containing clubroot resistance genes (CRa) against P. brassicae Pb4 was susceptible to PbE. To investigate the mechanism of cicRNAs responsible for clubroot disease resistance in B. rapa, circRNA-seq was performed with roots of ‘BJN 222’ at 0, 8, and 23 days …

Genetic Characterization Of Resistance To Bacterial Panicle Blight And Sheath Blight In Rice Using Qtl Linkage Analysis And Qtl-Seq, John Christian E. Ontoy

LSU Master's Theses

Bacterial panicle blight (BPB) and sheath blight (SB) are major diseases of rice causing significant yield reduction in conducive conditions. Few cultivars have shown reliable resistance to these diseases. In this study, a recombinant inbred line (RIL) population derived from the U.S. cultivars Jupiter (moderately resistant) and Trenasse (susceptible) was investigated to identify genomic regions associated with BPB and SB resistance. Phenotypes in BPB and SB, as well as days to heading (DH), of the RIL population were evaluated in the field. DH was found to be correlated to BPB and SB diseases. BPB was also positively correlated to SB. …

A Rapid Species-Specific Diagnostic Assay For Xylaria Necrophora, The Pathogen Behind Taproot Decline Of Soybean In The Southern United States, Sophie Baron Sheffield

Honors Capstones

No abstract provided.

Management Strategies And Distribution Of Aphanomyces Root Rot Of Alfalfa (Medicago Sativa), A Continuing Threat To Forage Production In The United States, Jennifer M. Giles, Conner L. Tordsen, Travis R. Rebstock, Bruna Bucciarelli, Deborah A. Samac, Andrew E. Sathoff

Research & Publications

Alfalfa (Medicago sativa) is one of several legumes that is affected by Aphanomyces root rot (ARR) caused by Aphanomyces euteiches. Symptoms of ARR on alfalfa seedlings include a yellow-grey discolouration of roots, rotting and loss of lateral roots, stunted growth, chlorotic foliage and reduction of nitrogen-producing nodules on roots. Infection can also occur on adult plants leading to loss of lateral roots and nodules. At the seedling stage, ARR decreases alfalfa stand establishment, and field longevity is reduced when adult plants are infected. A. euteiches is an oomycete pathogen that has motile zoospores and thick-walled oospores that …

Building Sustainable Rangeland Management Systems Through A One System Innovative Approach, Benedict C. Irwin, T. A. Ameha, M. Mangano, B. W. Solomon, T. Wood

IGC Proceedings (1977-2023)

Working through a collaborative working partnership between the USAID Feed the Future Resilience in Pastoralist Areas (RiPA)1 program and Land Governance Activity (LGA)2 and selected technical partners, these new rangeland programs aim to build on significant breakthrough successes in rangeland management from their previous lowland programs3. These new lowlands pastoralist development programs have been purposely positioned by USAID to coordinate, collaborate and combine working activities focused on the continued improvement and strengthening of rangeland management systems in the lowlands of Ethiopia. In light of this positioning, it is proposed that the programs work together to build a comprehensive sustainable rangeland …

Sustainable Development And The Transformation Of Female Rural Labor: The Case Of Woman Cattle Ranchers In Uruguay, Virginia Courdin

IGC Proceedings (1977-2023)

Internationally, rural women are considered key to sustainable development. However, in the Uruguayan livestock sector, women’s work is largely unrecognized by public policy makers, causing younger women to migrate, and resulting in the "masculinization" of livestock husbandry. In Uruguay, extensive livestock production (range livestock) analysis has historically ignored the genuinely productive role that women play in rangelands, limiting the visibility of their action to reproductive activities while ignoring their importance in terms of income generation, herd management, networking, strategic planning, etc. Although family production integrates women, their work is often invisible, subsumed within domestic chores or seen as "helping" the …

Ruminant Livestock Production Systems And Imperatives For Sustainable Development, J. W. Smith

IGC Proceedings (1977-2023)

No abstract provided.

Biodiversity Conservation And Sustainable Livelihoods In Rangelands: Trends, Challenges And Opportunities, J. Waithaka

IGC Proceedings (1977-2023)

Rangelands cover about 54% of the earth’s surface and are essential for agricultural and livestock production, environmental protection and the in-situ conservation of genetic resources. Despite providing services that support life on earth, rangelands have been neglected to a large extent when compared to other types of ecosystems. This paper provides an overview of the importance of rangelands in conserving biodiversity and supporting the livelihoods of millions of people globally. Rangelands have lost ecological integrity due to unsustainable anthropogenic land-use changes and impacts. It is estimated that over 80% of Key Biodiversity Areas (KBAs) are either not adequately protected or …

Feasibility Of Organic Certification Of Sheep And Goats Produced In Pastoral Systems In Northern Kenya, F. Von Steimker, H. T. Wario, B. Kaufmann

IGC Proceedings (1977-2023)

In pastoral systems of Kenya, sale of small ruminants is the main regular income source for most households. Although the meat of small ruminants produced in Marsabit county is preferred in the domestic market, no mechanisms are in place that allow for a respective price differentiation. Establishing value chains for labelled sheep and goat meat would be an option to allow pastoralists to profit from their high process and product quality. The aim of the current study is to assess the requirements and feasibility to establish a value chain for labelled products (e.g. origin labelled, organic certified) together with the …

Uses Of Native Plant Species Of A Communal Rangeland Within ‘Sierra De Huautla’ Protected Area, México, E. Cortés-Díaz, T. González-Bonilla, L. López-Aguilar, Pedro A. Martínez-Hernández, A. Hernández-Tapia

IGC Proceedings (1977-2023)

Sustainability of communal rangelands has become a major concern at national and international levels because land use conflicts and associated social conflicts allows for over-utilization of selected species making a high pressure on them and given away their places to species with no use at all becoming lands degraded and unproductive. The objective of the study was to determine floristic composition and native plant uses by local peasants. The range surface is of 4262 ha, belongs to the communal land ‘El Limon’, in Tepalcingo, Morelos, Mexico, and it is within the Natural Reserve Area “Sierra de Huautla”. Native vegetation is …