Plant Pathology Commons^™

Functional And Structural Analysis Of Fst1 In Fusarium Verticillioides, Chenxing Niu

Open Access Dissertations

Fusarium verticillioides causes an important seed disease on maize and produces fumonisin B1 (FB1), a mycotoxin that is detrimental to human and animal health. Previous studies discovered that expression of FST1 is required for FB1 production and wild-type level of virulence on maize seeds. FST1 encodes a putative protein with 12 transmembrane domains with sequence similarity to hexose transporters. However, those studies have failed to prove its ability to transport glucose, fructose or mannose. I identified another three phenotypes associated with the lack of a functional FST1, which includes reduced hydrophobicity of hyphae, reduced macroconidia production, and increased sensitivity to …

Role Of Viral Rna And Co-Opted Cellular Escrt-I And Escrt-Iii Factors In Formation Of Tombusvirus Spherules Harboring The Tombusvirus Replicase, Nikolay Kovalev, Isabel Fernández De Castro Martín, Judit Pogany, Daniel Barajas, Kunj Bihari Pathak, Cristina Risco, Peter D. Nagy

Plant Pathology Faculty Publications

Plus-stranded RNA viruses induce membrane deformations in infected cells in order to build viral replication complexes (VRCs). Tomato bushy stunt virus (TBSV) co-opts cellular ESCRT (endosomal sorting complexes required for transport) proteins to induce the formation of vesicle (spherule)-like structures in the peroxisomal membrane with tight openings toward the cytosol. In this study, using a yeast (Saccharomyces cerevisiae) vps23Δ bro1Δ double-deletion mutant, we showed that the Vps23p ESCRT-I protein (Tsg101 in mammals) and Bro1p (ALIX) ESCRT-associated protein, both of which bind to the viral p33 replication protein, play partially complementary roles in TBSV replication in cells …

Three-Year Survey Of Abundance, Prevalence And Genetic Diversity Of Chlorovirus Populations In A Small Urban Lake, Cristian F. Quispe, Olivia Sonderman, Anya Seng, Brenna Rasmussen, Garrett Weber, Claire Mueller, David Dunigan, James L. Van Etten

James Van Etten Publications

Inland water environments cover about 2.5 percent of our planet and harbor huge numbers of known and still unknown microorganisms. In this report, we examined water samples for the abundance, prevalence, and genetic diversity of a group of infectious viruses (chloroviruses) that infect symbiotic chlorella-like green algae. Samples were collected on a weekly basis for a period of 24 to 36 months from a recreational freshwater lake in Lincoln, Nebraska, and assayed for infectious viruses by plaque assay. The numbers of infectious virus particles were both host- and site-dependent. The consistent fluctuations in numbers of viruses suggest their impact as …

Regeneration And Transformation Of Common Bean (Phaseolus Vulgaris L.), Iqbal Singh

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

Common bean is the most important grain legume for direct human consumption and serves as main source of dietary protein for millions of people in developing world. Genetic transformation methods can serve as an important tool to complement traditional plant breeding methods for common bean improvement. Low transformation frequencies and unstable genetic integration associated with biolistic methods limits its use for routine transformation of common bean. In an attempt to develop Agrobacterium tumefaciens mediated transformation protocol for common bean, potential of primary leaves as an explant was analyzed following unsuccessful results with other tissues. Primary leaf explants were prepared from …

The Function Of A Putative Sumo E2 Enzyme In Plant Immunity, Huan Zhang

UCARE: Research Products

SUMO proteins are small ubiquitin-like modifiers. They can be attached to a target protein through a process called SUMOylation that involves an enzymatic cascade catalyzed by SUMO E1 (activating enzyme), E2 (conjugating enzyme) and E3 (ligation enzyme). Similar to ubiquitination, SUMOylation has been found in recent years to play a role in the regulation of pathogen-host ”arms race” (Chen, A. J., et al., 2013). However, the molecular mechanism behind the regulation is largely unexplored. To date, only ONE SUMO E2, UBC9 has been identified and confirmed to catalyze SUMOylation in human cell (Motion, G. B, et al., 2015). Nevertheless, recently …

Molecular Mechanisms Of Goss’S Wilt, Samuel Eastman, Guangyong Li, Fan Yang, Josh Herr, James R. Alfano

UCARE: Research Products

Clavibacter michiganensis subsp. Nebraskensis (Cmn) is a pathogen responsible for Goss’s Wilt in maize in the high plains. Strains of Clavibacter michiganensis subsp. Nebraskensis that are virulent and non-virulent in maize have been isolated, but the mechanism of this differentiation is not understood. Investigation of the genetic differences between virulent and non-virulent strains is providing an explanation as to how Cmn causes disease. Cmn mutants with reduced or removed virulence have been created using Tn5 transposon transformation to randomly knockout virulence factors. Potential effectors have also been identified in a genomic “virulence island” region by using bioinformatics.

A Colletotrichum Graminicola Mutant Deficient In The Establishment Of Biotrophy Reveals Early Transcriptional Events In The Maize Anthracnose Disease Interaction, Maria F. Torres, Noushin Ghaffari, Ester A. S. Buiate, Neil Moore, Scott Schwartz, Charles D. Johnson, Lisa J. Vaillancourt

Plant Pathology Faculty Publications

Background: Colletotrichum graminicola is a hemibiotrophic fungal pathogen that causes maize anthracnose disease. It progresses through three recognizable phases of pathogenic development in planta: melanized appressoria on the host surface prior to penetration; biotrophy, characterized by intracellular colonization of living host cells; and necrotrophy, characterized by host cell death and symptom development. A “Mixed Effects” Generalized Linear Model (GLM) was developed and applied to an existing Illumina transcriptome dataset, substantially increasing the statistical power of the analysis of C. graminicola gene expression during infection and colonization. Additionally, the in planta transcriptome of the wild-type was compared with that of …

Identifying Rare Fhb-Resistant Segregants In Intransigent Backcross And F2 Winter Wheat Populations, Anthony J. Clark, Daniela Sarti-Dvorjak, Gina Brown-Guedira, Yanhong Dong, Byung-Kee Baik, David A. Van Sanford

Plant and Soil Sciences Faculty Publications

Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)] in the US, is one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.). Infected grain is usually contaminated with deoxynivalenol (DON), a serious mycotoxin. The challenge in FHB resistance breeding is combining resistance with superior agronomic and quality characteristics. Exotic QTL are widely used to improve FHB resistance. Success depends on the genetic background into which the QTL are introgressed, whether through backcrossing or forward crossing; QTL expression is impossible to predict. In this study four high-yielding soft red …

Cell-Free And Cell-Based Approaches To Explore The Roles Of Host Membranes And Lipids In The Formation Of Viral Replication Compartment Induced By Tombusviruses, Peter D. Nagy, Judit Pogany, Kai Xu

Plant Pathology Faculty Publications

Plant positive strand RNA viruses are intracellular infectious agents that take advantage of cellular lipids and membranes to support replication and protect viral RNA from degradation by host antiviral responses. In this review, we discuss how Tomato bushy stunt virus (TBSV) co-opts lipid transfer proteins and modulates lipid metabolism and transport to facilitate the assembly of the membrane-bound viral replicase complexes within intricate replication compartments. Identification and characterization of the proviral roles of specific lipids and proteins involved in lipid metabolism based on results from yeast (Saccharomyces cerevisiae) model host and cell-free approaches are discussed. The review also …

Proceedings Of The 43rd Annual Meeting, Southern Soybean Disease Workers (March 9-10, 2016, Pensacola Beach, Florida), Trey Price, Tom Allen, Travis Faske, Eduardo Chagas Da Silva

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United States Soybean Disease Loss Estimates for 2015. TW Allen, CA Bradley, JP Damicone, NS Dufault, TR Faske, CA Hollier, T Isakeit, RC Kemerait, NM Kleczewski, SR Koenning, HL Mehl, JD Mueller, C Overstreet, PP Price, EJ Sikora, TN Spurlock, and H Young

Soilborne Disease Symposium (Tom Allen, moderator)

Integrated management of sudden death syndrome. D Mueller, L Leandro, Y Kandel, C Bradley, M Chilvers, A Tenuta, and K Wise

Field screening for stem canker: an outdated exercise or a necessary service for soybean growers? K Rowe and T Kirkpatrick

Nematode associated diseases in soybean. C Overstreet, …

Dedicated Industrial Oilseed Crops As Metabolic Engineering Platforms For Sustainable Industrial Feedstock Production, Li-Hua Zhu, Frans Krens, Mark A. Smith, Xueyuan Li, Weicong Qi, Elbertus N. Van Loo, Tim Iven, Ivo Feussner, Tara J. Nazarenus, Dongxin Huai, David C. Taylor, Xue-Rong Zhou, Allan G. Green, Jay Shockey, K. Thomas Klasson, Robert T. Mullen, Bangquan Huang, John M. Dyer, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Feedstocks for industrial applications ranging from polymers to lubricants are largely derived from petroleum, a non-renewable resource. Vegetable oils with fatty acid structures and storage forms tailored for specific industrial uses offer renewable and potentially sustainable sources of petrochemical-type functionalities. A wide array of industrial vegetable oils can be generated through biotechnology, but will likely require non-commodity oilseed platforms dedicated to specialty oil production for commercial acceptance. Here we show the feasibility of three Brassicaceae oilseeds crambe, camelina, and carinata, none of which are widely cultivated for food use, as hosts for complex metabolic engineering of wax esters for lubricant …

First Report Of Pythium Ultimum, P. Irregulare, Rhizoctonia Solani Ag4, And Fusarium Proliferatum From Arrowleaf Clover (Trifolium Vesiculosum): A Disease Complex, I. J. Pemberton, G. R. Smith, G. L. Philley, F. M. Rouquette, G. Y. Yuen

Department of Plant Pathology: Faculty Publications

Poor stand establishment, failure to recover after grazing, and premature plant death have reduced the utilization of arrowleaf clover (Trifolium vesiculosum Savi) as a forage crop in the southeastern United States in recent years. Clover plants collected from poor stands in east Texas pastures during the 1995 to 1996 and 1996 to 1997 seasons first exhibited root disease symptoms as young seedlings in the fall. Symptoms consisted of one or more of the following: tan discoloration of lateral roots and taproot; root pruning; and small, tan, sunken lesions on the taproot and crown. Many Rhizobium nodules were brown and …

Viral Replication Protein Inhibits Cellular Cofilin Actin Depolymerization Factor To Regulate The Actin Network And Promote Viral Replicase Assembly, Muhammad Shah Nawaz-Ul-Rehman, K. Reddisiva Prasanth, Kai Xu, Zsuzsanna Sasvari, Nikolay Kovalev, Isabel Fernández De Castro Martín, Daniel Barajas, Cristina Risco, Peter D. Nagy

Plant Pathology Faculty Publications

RNA viruses exploit host cells by co-opting host factors and lipids and escaping host antiviral responses. Previous genome-wide screens with Tomato bushy stunt virus (TBSV) in the model host yeast have identified 18 cellular genes that are part of the actin network. In this paper, we show that the p33 viral replication factor interacts with the cellular cofilin (Cof1p), which is an actin depolymerization factor. Using temperature-sensitive (ts) Cof1p or actin (Act1p) mutants at a semi-permissive temperature, we find an increased level of TBSV RNA accumulation in yeast cells and elevated in vitro activity of the tombusvirus replicase. We show …

Ginkgo And Welwitschia Mitogenomes Reveal Extreme Contrasts In Gymnosperm Mitochondrial Evolution, Wenhu Guo, Felix Grewe, Weishu Fan, Gregory J. Young, Volker Knoop, Jeffrey D. Palmer, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

Mitochondrial genomes (mitogenomes) of flowering plants are well known for their extreme diversity in size, structure, gene content, and rates of sequence evolution and recombination. In contrast, little is known about mitogenomic diversity and evolution within gymnosperms. Only a single complete genome sequence is available, from the cycad Cycas taitungensis, while limited information is available for the one draft sequence, from Norway spruce (Picea abies). To examine mitogenomic evolution in gymnosperms, we generated complete genome sequences for the ginkgo tree (Ginkgo biloba) and a gnetophyte (Welwitschia mirabilis). There is great disparity in size, …

Effect Of Volunteer Corn Density On Deoxynivalenol Production By Fusarium Graminearum In Hybrid Corn, Gaelle Florence Hollandbeck

Open Access Theses

Fusarium graminearum causes Gibberella ear rot in corn and produces mycotoxins such as deoxynivalenol (DON). Volunteer corn is a weed resulting from uncollected kernels from the previous harvest and is very difficult to control once established. An experiment was established in Porter County, IN from 2013 to 2015 to examine the impact of volunteer corn density on Gibberella ear rot severity and DON levels in hybrid corn. Five densities of volunteer corn were established within plots of each hybrid (0, 0.5, 2, 4, and 8 volunteer plants/m2). Disease severity and DON were assessed for both hybrid and volunteer ears collected …

A Bacterial Effector Co-Opts Calmodulin To Target The Plant Microtubule Network, Ming Guo, Panya Kim, Guangyong Li, Christian Elowsky, James R. Alfano

Center for Plant Science Innovation: Faculty Publications

The bacterial pathogen Pseudomonas syringae depends on effector proteins secreted by its type III secretion system for the pathogenesis of plants. The majority of these effector proteins are known suppressors of immunity, but their plant targets remain elusive. Using Arabidopsis thaliana as a model host, we report that the HopE1 effector uses the host calcium sensor, calmodulin (CaM), as a co-factor to target the microtubule- associated protein 65 (MAP65), an important component of the microtubule network. HopE1 interacted with MAP65 in a CaMdependent manner, resulting in MAP65-GFP dissociation from microtubules. Transgenic Arabidopsis expressing HopE1 had reduced secretion of the immunity …

Application Of Infrared And Raman Spectroscopy For The Identification Of Disease Resistant Trees, Anna O. Conrad, Pierluigi Bonello

Forest Health Research and Education Center Faculty Publications

New approaches for identifying disease resistant trees are needed as the incidence of diseases caused by non-native and invasive pathogens increases. These approaches must be rapid, reliable, cost-effective, and should have the potential to be adapted for high-throughput screening or phenotyping. Within the context of trees and tree diseases, we summarize vibrational spectroscopic and chemometric methods that have been used to distinguish between groups of trees which vary in disease susceptibility or other important characteristics based on chemical fingerprint data. We also provide specific examples from the literature of where these approaches have been used successfully. Finally, we discuss future …

Dry Edible Bean Disease Diagnostic Series, Samuel G. Markell, Robert M. Harveson, Julie Pasche

Department of Plant Pathology: Faculty Publications

Root Diseases

Fusarium root rot...................................PP1820-1

Pythium diseases..................................PP1820-2

Rhizoctonia root rot...............................PP1820-3

Soybean cyst nematode (SCN).............PP1820-4

Soybean cyst nematode sampling.........PP1820-5

Stem and Wilt Diseases

Bacterial wilt..........................................PP1820-6

Fusarium yellows (wilt)..........................PP1820-7

Stem rot.................................................PP1820-8

White mold.............................................PP1820-9

Foliar Diseases

Anthracnose........................................PP1820-10

Bacterial brown spot............................PP1820-11

Bean common mosaic virus................PP1820-12

Common bean rust..............................PP1820-13

Common bacterial blight .....................PP1820-14

Halo blight............................................PP1820-15

Fungicide Application Timing With Effects On Grey Leaf Spot And Southern Rust In Nebraska Field Corn, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides applied to three growth stages of corn for grey leaf spot (GLS) and southern rust (SR) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8% OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot) was planted at approximately 34,000 seed/A on 26 May. Eight treatments were arranged in a randomized complete …

Diseases Caused By Parasitic Nematodes, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Some plant-parasitic nematodes occur in every [sunflower] production field. Nematode populations likely include multiple species, although not all species cause notable disease. Symptoms depend on the species, the population density, and the crop's interaction with environmental factors. Several nematode species are known to cause disease in sunflower, although little research has focused on their impact or management in the crop. The highest population densities of plant-parasitic nematodes often occur in isolated areas that are randomly distributed in fields, as do the most severe plant symptoms. Symptoms are not necessarily diagnostic for nematodes, and the problem may be misdiagnosed. The most …