Plant Pathology Commons^™

Sunflower Disease Profiles I: Foliar Diseases, Robert M. Harveson, Loren J. Giesler, Tamra A. Jackson, Bo Liu, Stephen N. Wegulo, Kevin A. Korus

Department of Plant Pathology: Faculty Publications

Extension Circular 1900 (EC1900).

Photographs and disease descriptions of Viruses, Apical Chlorosis, Downy Mildew, Rust, Alternia Leaf Spot, and Bacterial Leaf Spot.

Critical Roles Of Rna-Binding Proteins In Mirna Biogenesis In Arabidopsis, Guodong Ren, Bin Yu

Center for Plant Science Innovation: Faculty Publications

MicroRNAs (miRNAs) are key regulators of gene expression and play critical roles in modulating metabolism, development and physiology in animals and plants. miRNA levels are transcriptionally and post-transcriptionally controlled for their proper function. Recent studies have shown that RNA-binding proteins play important roles in producing miRNAs by affecting the accurate and/or efficient processing of precursors of miRNAs. Many of these RNA-binding proteins also have roles in general RNA metabolism, indicating potential connections between miRNA biogenesis and other RNA metabolism. Here, we focus on the function of several RNA-binding proteins in miRNA biogenesis in Arabidopsis.

Post-Transcriptional Control Of Mirna Abundance In Arabidopsis, Guodong Ren, Bin Yu

Center for Plant Science Innovation: Faculty Publications

MicroRNAs (miRNAs) are a class of small non-coding RNAs (small RNAs) that are 20–24nt in length and predominantly repress gene expression at post-transcriptional levels. They regulate many biological processes including development, metabolism and physiology. Numerous studies have revealed that the steady-state levels of miRNA are under sophisticated control to ensure their proper function. In this review, we summarize recent advances on regulation of miRNA processing and stability in plants.

Uridylation Of Mirnas By Hen1 Suppressor1 In Arabidopsis, Guodong Ren, Xuemei Chen, Bin Yu

Center for Plant Science Innovation: Faculty Publications

HEN1-mediated 2′-O-methylation has been shown to be a key mechanism to protect plant microRNAs (miRNAs) and small interfering RNAs (siRNAs) as well as animal piwi-interacting RNAs (piRNAs) from degradation and 3′ terminal uridylation [1–8]. However, enzymes uridylating unmethylated miRNAs, siRNAs, or piRNAs in hen1 are unknown. In this study, a genetic screen identified a second-site mutation hen1 suppressor1-2 (heso1-2) that partially suppresses the morphological phenotypes of the hypomorphic hen1-2 allele and the null hen1-1 allele in Arabidopsis. HESO1 encodes a terminal nucleotidyl transferase that prefers to add untemplated uridine to the 3′ end of RNA, which is …

The Dna- And Rna-Binding Protein Factor Of Dna Methylation 1 Requires Xh Domain-Mediated Complex Formation For Its Function In Rna-Directed Dna Methylation, Meng Xie, Guodong Ren, Chi Zhang, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Studies have identified a sub-group of SGS3-LIKE proteins including FDM1–5 and IDN2 as key components of RNA-directed DNA methylation pathway (RdDM). Although FDM1 and IDN2 bind RNAs with 5' overhangs, their functions in the RdDM pathway remain to be examined. Here we show that FDM1 interacts with itself and with IDN2. Gel filtration suggests that FDM1 may exist as a homodimer in a heterotetramer complex in vivo. The XH domain of FDM1 mediates the FDM1–FDM1 and FDM1–IDN2 interactions. Deletion of the XH domain disrupts FDM1 complex formation and results in loss-of-function of FDM1. These results demonstrate that XH domainmediated …

Metabolic And Gene Expression Changes Triggered By Nitrogen Deprivation In The Photoautotrophically Grown Microalgae Chlamydomonas Reinhardtii And Coccomyxa Sp. C-169, Joseph Msanne, Di Xu, Anji Reddy Konda, J. Armando Casas-Mollano, Tala Awada, Edgar B. Cahoon, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Microalgae are emerging as suitable feedstocks for renewable biofuel production. Characterizing the metabolic pathways involved in the biosynthesis of energy-rich compounds, such as lipids and carbohydrates, and the environmental factors influencing their accumulation is necessary to realize the full potential of these organisms as energy resources. The model green alga Chlamydomonas reinhardtii accumulates significant amounts of triacylglycerols (TAGs) under nitrogen starvation or salt stress in medium containing acetate. However, since cultivation of microalgae for biofuel production may need to rely on sunlight as the main source of energy for biomass synthesis, metabolic and gene expression changes occurring in Chlamydomonas and …

Molecular And Biochemical Characterization Of Oleate- And Glycerol-3-Phosphate-Regulated Signaling In Plants, Mihir Kumar Mandal

Theses and Dissertations--Plant Pathology

Oleic acid (18:1), a monounsaturated fatty acid (FA), is synthesized upon desaturation of stearic acid (18:0) and this reaction is catalyzed by the plastidal enzyme stearoyl-acyl carrier protein-desaturase (SACPD). A mutation in the SSI2/FAB2 encoded SACPD lowers 18:1 levels, which correlates with induction of various resistance (R) genes and increased resistance to pathogens. Genetic and molecular studies have identified several suppressors of ssi2 which restore altered defense signaling either by normalizing 18:1 levels or by affecting function(s) of a downstream component. Characterization of one such ssi2 suppressor mutant showed that it is required downstream of low 18:1-mediated constitutive …

Tritimovirus P1 Functions As A Suppressor Of Rna Silencing And An Enhancer Of Disease Symptoms, Brock A. Young, Drake C. Stenger, Feng Qu, T. Jack Morris, Satyanarayana Tatineni, Roy French

Department of Plant Pathology: Faculty Publications

Wheat streak mosaic virus (WSMV) is an eriophyid mite-transmitted virus of the genus Tritimovirus, family Potyviridae. Complete deletion of helper component-proteinase (HC-Pro) has no effect on WSMV virulence or disease synergism, suggesting that a different viral protein suppresses RNA silencing. RNA silencing suppression assays using Nicotiana benthamiana 16C plants expressing GFP were conducted with each WSMV protein; only P1 suppressed RNA silencing. Accumulation of GFP siRNAs was markedly reduced in leaves infiltrated with WSMV P1 at both 3 and 6 days post infiltration relative to WSMV HC-Pro and the empty vector control. On the other hand, helper component-proteinase …

Evaluation Of Application Timing Efficacy Of Evito Fungicide On Field Corn In Nebraska, 2010, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 61-69, rating of “good” (5 out of 9) for gray leaf spot and “very good” (3 out of 9) for common rust, was planted on 29 Apr in 30-in. rows with a target population of 30,000 plants/A. The trial area was disked the previous fall with a crop history of six years of continuous corn. Three treatments and a non-treated control were replicated six times in a randomized complete block design. Each plot was four …

Evaluation Of Foliar Fungicide Application Timing On Efficacy Of Field Corn At Wcrec In Western Nebraska, 2011, C. M. Schleicher, C. Langemeier, G. Kruger, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln West Central Research and Extension Center at North Platte, NE. NuTech corn hybrid 3A513, rating of 5 out of 9 (1=best, 9=worst) for gray leaf spot was planted on 10 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked prior to planting with corn as the previous year’s crop. Furrows were built in season for flood irrigation. A herbicide program of Lumax (2.5 qt/A) + Atrazine (1 lb/A) + Glystar (20 oz/A) was applied on 25 Apr. 200 lb …

Evaluation Of Foliar Fungicide Application Timing On Efficacy Of Field Corn At Scal In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 5 May in 30 in. rows with a target population of 32,000 plants/A. The trial area had soybean as the previous year’s crop. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was applied to the trial …

Soybean Disease Profiles Ii: Stem And Root Rot Diseases, Loren J. Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Kevin A. Korus, Bo Liu, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1904 (EC1904).

Photographs and disease descriptions of Brown Stem Rot (BSR), Charcoal Rot, Fusarium Wilt and Root Rot, Phytophthora Root and Stem Rot, Pod and Stem Blight, Phomopsis Seed Decay, Rhizoctonia Root and Cortical Rot, Sclerotinia Stem Rot, Seedling Blights, Soybean Cyst Nematode (SCN), Stem Canker, and Sudden Death Syndrome (SDS).

Corn Disease Profile Iii: Ear Rot Diseases And Grain Molds, Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Bo Liu, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1901 (EC1901).

Under certain conditions, corn ear rot and grain mold diseases are common and can lead to loss of grain quality. Moldy grain can be docked or rejected at the elevator. Additionally, some ear and grain pathogens may produce secondary metabolites called mycotoxins, which are toxic to animals and humans consuming the contaminated grain. Mycotoxin-contaminated grain can also be docked or rejected. Mycotoxin production may start in the field and continue after harvest, or it may start during storage if mold infection begins there. When grain storage is necessary, drying grain to less than 15 percent moisture …

Sunflower Disease Profiles Ii: Head And Stalk Rots And Wilts, Robert M. Harveson, Loren J. Giesler, Tamra A. Jackson, Bo Liu, Stephen N. Wegulo, Kevin A. Korus

Department of Plant Pathology: Faculty Publications

Extension Circular 1902 (EC1902).

Photographs and disease descriptions of Phoma/Phomopsis Stalk Rots, Bacterial Stalk Rot, Verticillium Wilt, Rhizopus Head Rot, and White Mold/Sclerotina Diseases.

Corn Disease Update, Tamra A. Jackson, Craig B. Langemeier, Greg R. Kruger

Department of Plant Pathology: Faculty Publications

Goss's Bacterial Wilt and Blight ... Symptoms ... Management ... 2011 Survey ... Literature Cited

Gray Leaf Spot

Seedling Diseases and Stalk/Crown Root Diseases

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Factors Influencing Deoxynivalenol Accumulation In Small Grain Cereals, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Deoxynivalenol (DON) is a mycotoxin produced by the plant pathogenic fungi Fusarium graminearum and F. culmorum. These and other closely related fungi cause a disease known as Fusarium head blight (FHB) in small grain cereals. Other mycotoxins produced by FHB-causing fungi include nivalenol, T-2 toxin, and zearalenone. Ingestion of mycotoxin-contaminated food and feed can lead to toxicosis in humans and animals, respectively. DON is the predominant and most economically important of these mycotoxins in the majority of small grain-producing regions of the world. This review examines the factors that influence DON accumulation in small grain cereals from an agricultural perspective. …

Reflections On Plant And Soil Nematode Ecology: Past, Present And Future, Howard Ferris, Bryan S. Griffiths, Dorota L. Porazinska, Thomas O. Powers, Koon-Hui Wang, Mario Tenuta

Department of Plant Pathology: Faculty Publications

The purpose of this review is to highlight key developments in nematode ecology from its beginnings to where it stands today as a discipline within nematology. Emerging areas of research appear to be driven by crop production constraints, environmental health concerns, and advances in technology. In contrast to past ecological studies which mainly focused on management of plant-parasitic nematodes, current studies reflect differential sensitivity of nematode faunae. These differences, identified in both aquatic and terrestrial environments include response to stressors, environmental conditions, and management practices. Methodological advances will continue to influence the role nematodes have in addressing the nature of …

The Genome Of The Polar Eukaryotic Microalga Coccomyxa Subellipsoidea Reveals Traits Of Cold Adaptation, Guillaume Blanc, Irina V. Agarkova, Jane Grimwood, Alan Kuo, Andrew J. Brueggeman, David Dunigan, James Gurnon, Istvan Ladunga, Erika Lindquist, Susan Lucas, Jasmyn Pangilinan, Thomas Pröschold, Asaf Salamov, Jeremy Schmutz, Donald P. Weeks, Takashi Yamada, Alexandre Lomsadze, Mark Borodovsky, Jean-Michel Claverie, Igor V. Grigoriev, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Background: Little is known about the mechanisms of adaptation of life to the extreme environmental conditions encountered in polar regions. Here we present the genome sequence of a unicellular green alga from the division chlorophyta, Coccomyxa subellipsoidea C-169, which we will hereafter refer to as C-169. This is the first eukaryotic microorganism from a polar environment to have its genome sequenced.

Results: The 48.8 Mb genome contained in 20 chromosomes exhibits significant synteny conservation with the chromosomes of its relatives Chlorella variabilis and Chlamydomonas reinhardtii. The order of the genes is highly reshuffled within synteny blocks, suggesting that intra-chromosomal rearrangements …

Transgenic Expression Of Lactoferrin Imparts Enhanced Resistance To Head Blight Of Wheat Caused By Fusarium Graminearum, Jigang Han, Dilip K. Lakshman, Leny C. Galvez, Sharmila Mitra, P. Stephen Baenziger, Amitava Mitra

Department of Plant Pathology: Faculty Publications

Background: The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) that reduces both grain yield and quality.

Results: A construct containing a bovine lactoferrin cDNA was used to transform wheat using an Agrobacterium …

Assessing Genetic Diversity In The Web Blight Pathogen Thanatephorus Cucumeris (Anamorph = Rhizoctonia Solani) Subgroups Ag-1-Ie And Ag-1-If With Molecular Markers, N. González, James R. Steadman, Robert Higgins, Kent M. Eskridge

Department of Plant Pathology: Faculty Publications

Web blight, an important foliar disease of dry beans in the Americas, is a challenge to manage. We studied genetic variation of 92 isolates of Rhizoctonia solani subgroups AG-1-IE and AG-1-IF using DNA fingerprinting methods and mycelial compatibility grouping. The isolates were collected over 13 years from bean fields in the Dominican Republic, Honduras and Puerto Rico. Cluster and AMOVA analysis of combined data from two universal rice primers and two internal sequence repeats revealed significant genetic variation among and within populations of both subgroups. Variation was influenced by geographic origin and sampling year for AG-1-IE isolates and geographic origin …