Plant Pathology Commons^™

Residues Responsible For The Selectivity Of Α-Conotoxins For Ac-Achbp Or Nachrs, Bo Lin, Shi-Hua Xiang, Mengsen Li

Center for Plant Science Innovation: Faculty Publications

Nicotinic acetylcholine receptors (nAChRs) are targets for developing new drugs to treat severe pain, nicotine addiction, Alzheimer disease, epilepsy, etc. α-Conotoxins are biologically and chemically diverse. With 12–19 residues and two disulfides, they can be specifically selected for different nAChRs. Acetylcholine-binding proteins from Aplysia californica (Ac-AChBP) are homologous to the ligand-binding domains of nAChRs and pharmacologically similar. X-ray structures of the α-conotoxin in complex with Ac-AChBP in addition to computer modeling have helped to determine the binding site of the important residues of α-conotoxin and its affinity for nAChR subtypes. Here, we present the various α-conotoxin residues that are selective …

Screen Of Non-Annotated Small Secreted Proteins Of Pseudomonas Syringae Reveals A Virulence Factor That Inhibits Tomato Immune Proteases, Takayuki Shindo, Farnusch Kaschani, Fan Yang, Judit Kovács, Fang Tian, Jiorgos Kourelis, Tram Ngoc Hong, Tom Colby, Mohammed Shabab, Rohini Chawla, Selva Kumari, Muhammed Ilyas, Anja C. Hörger, James R. Alfano, Renier A. L. Van Der Hoorn

Center for Plant Science Innovation: Faculty Publications

Pseudomonas syringae pv. tomato DC3000 (PtoDC3000) is an extracellular model plant pathogen, yet its potential to produce secreted effectors that manipulate the apoplast has been under investigated. Here we identified 131 candidate small, secreted, non-annotated proteins from the PtoDC3000 genome, most of which are common to Pseudomonas species and potentially expressed during apoplastic colonization. We produced 43 of these proteins through a custom-made gateway-compatible expression system for extracellular bacterial proteins, and screened them for their ability to inhibit the secreted immune protease C14 of tomato using competitive activity-based protein profiling. This screen revealed C14-inhibiting protein-1 (Cip1), which contains motifs of …

Limited Mitogenomic Degradation In Response To A Parasitic Lifestyle In Orobanchaceae, Weishu Fan, Andan Zhu, Melisa Kozaczek, Neethu Shah, Natalia Pabón-Mora, Favio González, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

In parasitic plants, the reduction in plastid genome (plastome) size and content is driven predominantly by the loss of photosynthetic genes. The first completed mitochondrial genomes (mitogenomes) from parasitic mistletoes also exhibit significant degradation, but the generality of this observation for other parasitic plants is unclear. We sequenced the complete mitogenome and plastome of the hemiparasite Castilleja paramensis (Orobanchaceae) and compared them with additional holoparasitic, hemiparasitic and nonparasitic species from Orobanchaceae. Comparative mitogenomic analysis revealed minimal gene loss among the seven Orobanchaceae species, indicating the retention of typical mitochondrial function among Orobanchaceae species. Phylogenetic analysis demonstrated that the mobile cox1 …

Identification Of Homogentisate Dioxygenase As A Target For Vitamin E Biofortification In Oilseeds, Minviluz G. Stacey, Rebecca E. Cahoon, Hanh T. Nguyen, Yaya Cui, Shirley Sato, Cuong T. Nguyen, Nongnat Phoka, Kerry M. Clark, Yan Liang, Joe Forrester, Josef Batek, Phat Tien Do, David A. Sleper, Thomas E. Clemente, Edgar B. Cahoon, Gary Stacey

Center for Plant Science Innovation: Faculty Publications

Soybean (Glycine max) is a major plant source of protein and oil and produces important secondary metabolites beneficial for human health. As a tool for gene function discovery and improvement of this important crop, a mutant population was generated using fast neutron irradiation. Visual screening of mutagenized seeds identified a mutant line, designated MO12, which produced brown seeds as opposed to the yellow seeds produced by the unmodified Williams 82 parental cultivar. Using forward genetic methods combined with comparative genome hybridization analysis, we were able to establish that deletion of the GmHGO1 gene is the genetic basis of …

Triticum Mosaic Virus Exhibits Limited Population Variation Yet Shows Evidence Of Parallel Evolution After Replicated Serial Passage In Wheat, Melissa S. Bartels, Roy French, Robert A. Graybosch, Satyanarayana Tatineni

Department of Plant Pathology: Faculty Publications

An infectious cDNA clone of Triticum mosaic virus (TriMV) (genus Poacevirus; family Potyviridae) was used to establish three independent lineages in wheat to examine intra-host population diversity levels within protein 1 (P1) and coat protein (CP) cistrons over time. Genetic variation was assessed at passages 9, 18 and 24 by single-strand conformation polymorphism, followed by nucleotide sequencing. The founding P1 region genotype was retained at high frequencies in most lineage/passage populations, while the founding CP genotype disappeared after passage 18 in two lineages.We found that rare TriMV genotypes were present only transiently and lineages followed independent evolutionary trajectories, …

Foliar Fungicide Application Timing For Disease Management, Stay Green, And Yield In Nebraska, 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 at different corn growth stages for gray 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 % organic matter, and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to GLS) was planted at approximately 34,000 seed/A on 26 May, which is later than normal, due to wet spring …

Foliar Fungicide Modes Of Action For Southern Rust Management, Push Lodging, And Yield In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides with different modes of action for 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 % organic matter, 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 (GLS)) was planted at approximately 34,000 seed/A on 26 May. Eight treatments were arranged in a randomized complete block design with six …

Deposition Aid Adjuvants Plus A Fungicide For Southern Rust Management, Stay Green, Push Lodging, And Yield Comparisons In Field Corn In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides for 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 (GLS)) was planted at approximately 34,000 seed/A on 26 May. Eleven treatments were arranged in a randomized complete block design with six replications. . . . Phytotoxicity was …

Root-Lesion Nematodes, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Root-lesion nematodes, Pratylenchus spp., are among the most commonly encountered plant-parasitic nematodes, with one or more species occurring in almost every field. Their small size (0.4-0.7 mm long) relative to most other plant-parasitic nematodes enables them to survive in almost any soil texture. Their wide host range and distribution make them one of the most damaging nematodes worldwide, ranging from cool temperate to tropical environments. At least eight species of root-lesion nematodes have been associated with sunflower.

Root-Knot Nematodes, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Root-knot nematodes, Meloidogyne spp., are some of the most damaging plant pathogens. Several of the most common species of root-knot nematodes have been confirmed to reproduce and cause damage on sunflower, including M. arenaria, M. hapla, M. incognita, M. javanica, and M. hispanica.

Meloidogyne spp. occur worldwide but are especially common in temperate, subtropical, and tropical regions. Countries where Meloidogyne spp. have been confirmed to affect sunflower include the United States and the African nations of Egypt, Mozambique, South Africa, and Zambia. Root-knot nematodes tend to cause the most damage to plants grown in sandy …

Northern Corn Leaf Blight, Tamra A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Northern corn leaf blight (NCLB) is a disease of corn caused by a fungus, Exserohilum turcicum (sexual stage Setosphaeria turcica). Its development is favored by cool to moderate temperatures and high relative humidity. Historically, NCLB has been more common and severe in states in the eastern Corn Belt, but its incidence has increased in Nebraska and the western Corn Belt in recent years. The disease is distributed throughout most of the corn-growing areas of the United States. The disease also occurs sporadically throughout other humid corn-producing areas of the world. In Nebraska, the disease has been most serious in …

Identification Of Erwinia Rhapontici As The Causal Agent Of Crown And Shoot Rot And Pink Seed Of Pea In Nebraska, Anthony O. Adesemoye, Hsin-Ho Wei, Robert M. Harveson

Department of Plant Pathology: Faculty Publications

Over the last five years, the production of dry yellow peas (Pisum sativum L.) has been increasing in Nebraska and other areas of the Central High Plains, according to a USDA report (Jasa 2013). Dry pea is a short-season crop with a low water requirement, making it a good rotational crop for the high plains. We have noted bacterial pathogens, potentially a disease complex, that may negatively impact the production of pea in this region, and one of the emerging pathogens is Erwinia rhapontici. This pathogen is a gram-negative bacterium that has been reported from soil, seed, and …

Transcriptome Profiling Of Buffalograss Challenged With The Leaf Spot Pathogen Curvularia Inaequalis, Bimal S. Amaradasa, Keenan Amundsen

Department of Plant Pathology: Faculty Publications

Buffalograss (Bouteloua dactyloides) is a low maintenance U. S. native turfgrass species with exceptional drought, heat, and cold tolerance. Leaf spot caused by Curvularia inaequalis negatively impacts buffalograss visual quality. Two leaf spot susceptible and two resistant buffalograss lines were challenged with C. inaequalis. Samples were collected from treated and untreated leaves when susceptible lines showed symptoms. Transcriptome sequencing was done and differentially expressed genes were identified. Approximately 27 million raw sequencing reads were produced per sample. More than 86% of the sequencing reads mapped to an existing buffalograss reference transcriptome. De novo assembly of unmapped reads …

Morphological And Molecular Characterization Of Gracilacus Wuae N. Sp. (Nematoda: Criconematoidea) Associated With Cow Parsnip (Heracleum Maximum) In Ontario, Canada, Qing Yu, Weimin Ye, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Gracilacus wuae n. sp. from soil associated with cow parsnip in Ontario, Canada is described and illustrated. Morphologically, females have a long stylet ranging from 80 to 93 mmlong, the lip region not offset from the body contour, without lateral lips but with large and flat submedian lobes, the mouth opening slit-like elongated laterally and surrounded by lateral flaps, the excretory pore is anterior to the knobs of the stylet; males without stylet and the pharynx degenerated. The fourth-stage juveniles lack a stylet, the pharynx degenerated, and can be differentiated into preadult females and males based on the position of …

Root Rot Pathogens Of Wheat In South Dakota And Their Affect On Seed Germination And Seedling Blight In Spring Wheat Cultivars, Navjot Kaur

Electronic Theses and Dissertations

Crown rot and common root rot are the important root diseases in wheat (Triticum aestivum L.) and other cereals causing significant germination and yield losses in the Northern Great Plains and other parts of the world. Bipolaris sorokiniana (Bs) and Fusarium graminearum (Fg) cause common root rot and crown rot respectively, are the important wheat root pathogens that can affect seed germination, seedling establishment and impact crop productivity. A survey was conducted in the year 2014 and 2015 to study the distribution and the prevalence of root rot pathogens in South Dakota. Out of 31 and eight roots samples …

Snrna 3' End Processing By A Cpsf73- Containing Complex Essential For Development In Arabidopsis, Yunfeng Liu, Shengjun Li, Yuan Chen, Athen N. Kimberlin, Edgar B. Cahoon, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Uridine-rich small nuclear RNAs (snRNAs) are the basal components of the spliceosome and play essential roles in splicing. The biogenesis of the majority of snRNAs involves 3’ end endonucleolytic cleavage of the nascent transcript from the elongating DNA-dependent RNA ploymerase II. However, the protein factors responsible for this process remain elusive in plants. Here, we show that DEFECTIVE in snRNA PROCESSING 1 (DSP1) is an essential protein for snRNA 3’ end maturation in Arabidopsis. A hypomorphic dsp1-1 mutation causes pleiotropic developmental defects, impairs the 3’ end processing of snRNAs, increases the levels of snRNA primary transcripts (pre-snRNAs), and alters …

Evolutionary Dynamics Of The Plastid Inverted Repeat: The Effects Of Expansion, Contraction, And Loss On Substitution Rates, Andan Zhu, Wenhu Guo, Weishu Fan, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

• Rates of nucleotide substitution were previously shown to be several times slower in the plastid inverted repeat (IR) compared with single-copy (SC) regions, suggesting that the IR provides enhanced copy-correction activity.

• To examine the generality of this synonymous rate dependence on the IR, we compared plastomes from 69 pairs of closely related species representing 52 families of angiosperms, gymnosperms, and ferns.

• We explored the breadth of IR boundary shifts in land plants and demonstrate that synonymous substitution rates are, on average, 3.7 times slower in IR genes than in SC genes. In addition, genes moved from the SC into the …

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Genetic Diversity Of Colletotrichum Sublineola On Sweet Sorghum And Wild Sorghum Relatives In Kentucky And The Southeastern U.S., Katia Viana Xavier

Theses and Dissertations--Plant Pathology

Anthracnose, caused by the fungus Colletotrichum sublineola, is one of the most important diseases on sorghum (Sorghum bicolor) in the United States (U.S.) and worldwide. The production of sweet sorghum for feedstock has been increasing in the Southeastern U.S. (SE), and anthracnose has emerged as a significant production constraint. Anthracnose is also common on the ubiquitous wild sorghum relative, johnsongrass (Sorghum halepense). The degree to which the pathogen population on johnsongrass contributes to disease epidemics on cultivated sorghum (S. bicolor) in the SE is unknown. Genetic and pathological diversity was characterized among a …

Mechanisms, Applications, And Perspectives Of Antiviral Rna Silencing In Plants / Mecanismos, Aplicaciones Y Perspectivas Del Silenciamiento Génico De Virus En Plantas, Hernan Garcia-Ruiz, Mayra Teresa Garcia Ruiz, Sergio Manuel Gabriel Peralta, Cristina Betzabeth Miravel Gabriel, Kaoutar El-Mounadi

Department of Plant Pathology: Faculty Publications

Viral diseases of plants cause important economic losses due to reduction in crop quality and quantity to the point of threatening food security in some countries. Given the reduced availability of natural sources, genetic resistance to viruses has been successfully engineered for some plant-virus combinations. A sound understanding of the basic mechanisms governing plant-virus interactions, including antiviral RNA silencing, is the foundation to design better management strategies and biotechnological approaches to engineer and implement antiviral resistance in plants. In this review, we present current molecular models to explain antiviral RNA silencing and its application in basic plant research, biotechnology and …

Combating A Global Threat To A Clonal Crop: Banana Black Sigatoka Pathogen Pseudocercospora Fijiensis (Synonym Mycosphaerella Fijiensis) Genomes Reveal Clues For Disease Control, Rafael E. Arango-Isaza, Caucasella Diaz-Trujillo, Braham Deep Singh Dhillon, Andrea L. Aerts, Jean Carlier, Charles F. Crane, Tristan V. De Jong, Ineke M. De Vries, Robert A. Dietrich, Andrew D. Farmer, Claudia Fortes Fereira, Suzana A L Garcia, Mauricio Guzmán, Richard C. Hamelin, Erika A. Lindquist, Rahim Mehrabi, Olman Quiros, Jeremy Schmultz, Harris J. Shapiro, Elizabeth Reynolds, Gabriel Scalliet, Manoel Teixeira Souza, Ioannis Stergiopoulos, Theo A J Van Der Lee, Pierre J G M De Wit, Marie Françoise Zapater, Lute Harm Zwiers, Igor V. Grigoriev, Stephen B. Goodwin, Gert Hj J Kema

Department of Botany and Plant Pathology Faculty Publications

Black Sigatoka or black leaf streak disease, caused by the Dothideomycete fungus Pseudocercospora fijiensis (previously: Mycosphaerella fijiensis), is the most significant foliar disease of banana worldwide. Due to the lack of effective host resistance, management of this disease requires frequent fungicide applications, which greatly increase the economic and environmental costs to produce banana. Weekly applications in most banana plantations lead to rapid evolution of fungicide-resistant strains within populations causing disease-control failures throughout the world. Given its extremely high economic importance, two strains of P. fijiensis were sequenced and assembled with the aid of a new genetic linkage map. The 74-Mb …