Life Sciences Commons^™

Ecological And Morphological Differentiation Among Coi Haplotype Groups In The Plant Parasitic Nematode Species Mesocriconema Xenoplax, Julianne N. Matczyszyn, Timothy Harris, Kirsten S. Powers, Sydney E. Everhart, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

DNA barcoding with the mitochondrial COI gene reveals distinct haplotype subgroups within the monophyletic and parthenogenetic nematode species, Mesocriconema xenoplax. Biological attributes of these haplotype groups (HG) have not been explored. An analysis of M. xenoplax from 40 North American sites representing both native plant communities and agroecosystems was conducted to identify possible subgroup associations with ecological, physiological, or geographic factors. A dataset of 132 M. xenoplax specimens was used to generate sequences of a 712 bp region of the cytochrome oxidase subunit I gene. Maximum-likelihood and Bayesian phylogenies recognized seven COI HG (≥99/0.99 posterior probability/bootstrap value). Species delimitation …

Ecological And Morphological Differentiation Among Coi Haplotype Groups In The Plant Parasitic Nematode Species Mesocriconema Xenoplax, Julianne N. Matczyszyn, Timothy Harris, Kirsten S. Powers, Sydney E. Everhart, Tom Powers

Department of Plant Pathology: Faculty Publications

DNA barcoding with the mitochondrial COI gene reveals distinct haplotype subgroups within the monophyletic and parthenogenetic nematode species, Mesocriconema xenoplax. Biological attributes of these haplotype groups (HG) have not been explored. An analysis of M. xenoplax from 40 North American sites representing both native plant communities and agroecosystems was conducted to identify possible subgroup associations with ecological, physiological, or geographic factors. A dataset of 132 M. xenoplax specimens was used to generate sequences of a 712 bp region of the cytochrome oxidase subunit I gene. Maximum-likelihood and Bayesian phylogenies recognized seven COI HG (≥99/0.99 posterior probability/bootstrap value). Species …

Global Distribution And Richness Of Armillaria And Related Species Inferred From Public Databases And Amplicon Sequencing Datasets, Rachel A. Koch, Joshua Herr

Department of Plant Pathology: Faculty Publications

Armillaria is a globally distributed fungal genus most notably composed of economically important plant pathogens that are found predominantly in forest and agronomic systems. The genus sensulato has more recently received attention for its role in woody plant decomposition and in mycorrhizal symbiosis with specific plants. Previous phylogenetic analyses suggest that around 50 species are recognized globally. Despite this previous work, no studies have analyzed the global species richness and distribution of the genus using data derived from fungal community sequencing datasets or barcoding initiatives. To assess the global diversity and species richness of Armillaria, we mined publicly available sequencing …

Transcriptomics Reveals The Putative Mycoparasitic Strategy Of The Mushroom Entoloma Abortivum On Species Of The Mushroom Genus Armillaria, Rachel A. Koch, Joshua Herr

Department of Plant Pathology: Faculty Publications

During mycoparasitism, a fungus—the host—is parasitized by another fungus—the mycoparasite. The genetic underpinnings of these relationships have been best characterized in ascomycete fungi. However, within basidiomycete fungi, there are rare instances of mushroom-forming species parasitizing the reproductive structures, or sporocarps, of other mushroom-forming species, which have been rarely investigated on a genetic level. One of the most enigmatic of these occurs between Entoloma abortivum and species of Armillaria, where hyphae of E. abortivum are hypothesized to disrupt the development of Armillaria sporocarps, resulting in the formation of carpophoroids. However, it remains unknown whether carpophoroids are the direct result of a …

A Phytobacterial Tir Domain Effector Manipulates Nad+ To Promote Virulence, Samuel Eastman, Thomas Smith, Mark A. Zaydman, Panya Kim, Samuel Martinez, Neha Damaraju, Aaron Diantonio, Jeffrey Milbrandt, Thomas E. Clemente, James R. Alfano, Ming Guo

Department of Plant Pathology: Faculty Publications

• The Pseudomonas syringae DC3000 type III effector HopAM1 suppresses plant immunity and contains a Toll/interleukin-1 receptor (TIR) domain homologous to immunity-related TIR domains of plant nucleotide-binding leucine-rich repeat receptors that hydrolyze nicotinamide adenine dinucleotide (NAD⁺) and activate immunity. In vitro and in vivo assays were conducted to determine if HopAM1 hydrolyzes NAD⁺ and if the activity is essential for HopAM1’s suppression of plant immunity and contribution to virulence.
• HPLC and LC-MS were utilized to analyze metabolites produced from NAD⁺ by HopAM1 in vitro and in both yeast and plants. Agrobacterium-mediated transient expression and in planta …

Meta-Analysis Identifies Pleiotropic Loci Controlling Phenotypic Trade-Offs In Sorghum, Ravi V. Mural, Marcin Grzybowski, Miao Chenyong, Alyssa Damke, Sirjan Sapkota, Richard E. Boyles, Maria G. Salas Fernandez, Patrick S. Schnable, Brandi Sigmon, Stephen Kresovich, James C. Schnable

Department of Plant Pathology: Faculty Publications

Community association populations are composed of phenotypically and genetically diverse accessions. Once these populations are genotyped, the resulting marker data can be reused by different groups investigating the genetic basis of different traits. Because the same genotypes are observed and scored for a wide range of traits in different environments, these populations represent a unique resource to investigate pleiotropy. Here, we assembled a set of 234 separate trait datasets for the Sorghum Association Panel, a group of 406 sorghum genotypes widely employed by the sorghum genetics community. Comparison of genome-wide association studies (GWAS) conducted with two independently generated marker sets …

Origin Of Agricultural Plant Pathogens: Diversity And Pathogenicity Of Rhizoctonia Fungi Associated With Native Prairie Grasses In The Sandhills Of Nebraska, Srikanth Kodati, Anthony O. Adesemoye, Gary Y. Yuen, Jerry Volesky, Sydney E. Everhart

Department of Plant Pathology: Faculty Publications

The Sandhills of Nebraska is a complex ecosystem, covering 50,000 km² in central and western Nebraska and predominantly of virgin grassland. Grasslands are the most widespread vegetation in the U.S. and once dominated regions are currently cultivated croplands, so it stands to reason that some of the current plant pathogens of cultivated crops originated from grasslands, particularly soilborne plant pathogens. The anamorphic genus Rhizoctonia includes genetically diverse organisms that are known to be necrotrophic fungal pathogens, saprophytes, mycorrhiza of orchids, and biocontrol agents. This study aimed to evaluate the diversity of Rhizoctonia spp. on four native grasses in the …

Changes In Subcellular Localization Of Host Proteins Induced By Plant Viruses, Rosalba Rodriguez-Pena, Kaoutar El Mounadi, Hernan Garcia-Ruiz

Department of Plant Pathology: Faculty Publications

Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the …

Widespread Mortality Of Trembling Aspen (Populus Tremuloides) Throughout Interior Alaskan Boreal Forests Resulting From A Novel Canker Disease, Roger W. Ruess, Loretta M. Winton, Gerard C. Adams

Department of Plant Pathology: Faculty Publications

Over the past several decades, growth declines and mortality of trembling aspen throughout western Canada and the United States have been linked to drought, often interacting with outbreaks of insects and fungal pathogens, resulting in a “sudden aspen decline” throughout much of aspen’s range. In 2015, we noticed an aggressive fungal canker causing widespread mortality of aspen throughout interior Alaska and initiated a study to quantify potential drivers for the incidence, virulence, and distribution of the disease. Stand-level infection rates among 88 study sites distributed across 6 Alaska ecoregions ranged from <1 to 69%, with the proportion of trees with canker that were dead averaging 70% across all sites. The disease is most prevalent north of the Alaska Range within the Tanana Kuskokwim ecoregion. Modeling canker probability as a function of ecoregion, stand structure, landscape position, and climate revealed that smaller-diameter trees in older stands with greater aspen basal area have the highest canker incidence and mortality, while younger trees in younger stands appear virtually immune to the disease. Sites with higher summer vapor pressure deficits had significantly higher levels of canker infection and mortality. We believe the combined effects of this novel fungal canker pathogen, drought, and the persistent aspen leaf miner outbreak are triggering feedbacks between carbon starvation and hydraulic failure that are ultimately driving widespread mortality. Warmer early-season temperatures and prolonged late summer drought are leading to larger and more severe wildfires throughout interior Alaska that are favoring a shift from black spruce to forests dominated by Alaska paper birch and aspen. Widespread aspen mortality fostered by this rapidly spreading pathogen has significant implications for successional dynamics, ecosystem function, and feedbacks to disturbance regimes, particularly on sites too dry for Alaska paper birch.

Root And Crown Rot Pathogens Found On Dry Beans Grown In Mozambique, Suzana Vanessa Ismael Fernandes, G. Godoy-Lutz, Celestina Nhagupana Jochua, Carlos A. Urrea, Kent M. Eskridge, James R, Steadman, Joshua Herr

Department of Plant Pathology: Faculty Publications

Dry edible beans are a vital food source in Mozambique, East Africa—one that alleviates hunger and malnutrition and adds value to the economy. In recent years, root/crown rot (RCR) pathogens have emerged as limiting constraints in dry bean production. Not much has been characterized concerning the causal agents of RCR in Mozambique. The purpose of this study was to identify the primary pathogen(s) associated with RCR dry bean samples collected at breeder nursery sites and farmer fields in Mozambique using molecular sequencing and culture-based methods. Sequencing revealed, not surprisingly, an increased diversity of fungal/oomycete operational taxonomic units when compared to …

Stop Helping Pathogens: Engineering Plant Susceptibility Genes For Durable Resistance, Hernan Garcia-Ruiz, Boris Szurek, Guido Van Den Ackerveken

Department of Plant Pathology: Faculty Publications

Alternatives to protect crops against diseases are desperately needed to secure world food production and make agriculture more sustainable. Genetic resistance to pathogens utilized so far is mostly based on single dominant resistance genes that mediate specific recognition of invaders and that is often rapidly broken by pathogen variants. Perturbation of plant susceptibility (S) genes offers an alternative providing plants with recessive resistance that is proposed to be more durable. S genes enable the establishment of plant disease, and their inactivation provides opportunities for resistance breeding of crops. However, loss of S gene function can have pleiotropic effects. Developments in …

Poplar Allene Oxide Synthase 1 Gene Promoter Drives Rapid And Localized Expression By Wounding, Bin Lei, Christopher J. Frost, Tao Xu, Joshua Herr, John E. Carlson, Haiying Liang

Department of Plant Pathology: Faculty Publications

Promoters play critical roles in controlling the transcription of genes and are important as tools to drive heterologous expression for biotechnological applications. In addition to core transcription factor-binding motifs that assist in the binding of RNA polymerases, there are specific nucleotide sequences in a promoter region to allow regulation of gene expression. The allene oxide synthase (AOS) gene family are cytochrome P450s that are responsive to a variety of environmental stress, making them good candidates for the discovery of inducible promoters. Populus AOS homologs separate phylogenetically into two clades. Based on the 19 promoter motifs with significant abundance differences between …

Pratylenchus Smoliki, A New Nematode Species (Pratylenchidae: Tylenchomorpha) From The Great Plains Region Of North America, Thomas Powers, Timothy Todd, Tim Harris, Rebecca Higgins, Ann Macguidwin, Peter Mullin, Mehmet Ozbayrak, Kirsten Powers, Kanan Sakai

Department of Plant Pathology: Faculty Publications

Pratylenchus smoliki is a new species of root-lesion nematode described from corn-soybean production fields in the Central Great Plains of North America. It is characterized by populations with relatively abundant males, two lip annuli, females with a round functional spermatheca and a conoid to subcylindrical tail with a non-crenate, smooth terminus. In host preference tests, corn and wheat produce the largest nematode populations, whereas sorghum and soybeans produce less than 20% the numbers observed on corn. Scanning electron microscopy reveals that the en face patterns compare to those seen in Pratylenchus pseudocoffeae, P. scribneri, P. hexincisus, and …

Lichens And Biofilms: Common Collective Growth Imparts Similar Developmental Strategies, Erin C. Carr, Steven D. Harris, Joshua R. Herr, Wayne Riekhof

Department of Plant Pathology: Faculty Publications

Lichens are traditionally defined as a symbiotic relationship between fungi and algae and/or cyanobacteria. This union forms a unique structure called the thallus, which attaches to surfaces such as rocks and tree bark. Recent reports challenge the view that lichens are comprised of one fungus and one photobiont, and instead suggest that they are a consortium of microbes. Much of lichen biology remains unknown as most of our knowledge of lichens is limited to morphological characteristics with little to no functional analysis of lichen genes. However, lichens and biofilms share many similar physiological traits which when compared may assist in …

Genetic (Co)Variation And Accuracy Of Selection For Resistance To Viral Mosaic Disease And Production Traits In An Inter-Ecotypic Switchgrass Breeding Population, Serge J. Edmé, Gautam Sarath, Nathan Palmer, Gary Y. Yuen, Anthony A. Muhle, Rob Mitchell, Satyanarayana Tatineni, Christian Tobias

Department of Plant Pathology: Faculty Publications

Obtaining good accuracy and reliability of estimated breeding values is essential to increase the efficiency of a plant breeding program. Genetic variation was assessed for categorical (Virc) and binary (Virb) mosaic (caused by Panicum mosaic virus), dry matter (DMY) and predicted ethanol (Etoh) yields, and lignin content (Klason or KL, and acid-detergent or ADL) in a Summer–Kanlow switchgrass (Panicum virgatum L.) population. Breeding values were predicted with the restricted maximum likelihood–best linear unbiased prediction (REML-BLUP) approaches using a multivariate phenotypic (PBLUP) and animal (ABLUP) models, integrating a three-generation pedigree (1,622 half-sibs) in ABLUP and not in PBLUP. Models …

Transcriptomics Reveals The Putative Mycoparasitic Strategy Of The Mushroom Entoloma Abortivum On Species Of The Mushroom Genus Armillaria, Rachel A. Koch, Joshua R. Herr

Department of Plant Pathology: Faculty Publications

During mycoparasitism, a fungus—the host—is parasitized by another fungus—the mycoparasite. The genetic underpinnings of these relationships have been best characterized in ascomycete fungi. However, within basidiomycete fungi, there are rare instances of mushroom-forming species parasitizing the reproductive structures, or sporocarps, of other mushroom-forming species, which have been rarely investigated on a genetic level. One of the most enigmatic of these occurs between Entoloma abortivum and species of Armillaria, where hyphae of E. abortivum are hypothesized to disrupt the development of Armillaria sporocarps, resulting in the formation of carpophoroids. However, it remains unknown whether carpophoroids are the direct result of …