Other Plant Sciences Commons^™

Four Common Setaria Species Are Alternative Hosts For Clavibacter Michiganensis Subsp. Nebraskensis, Causal Agent Of Goss's Bacterial Wilt And Blight Of Corn, Craig B. Langemeier, Tamra A. Jackson-Ziems, Greg R. Kruger

Department of Plant Pathology: Faculty Publications

Goss’s bacterial wilt and blight, caused by Clavibacter michiganensis subsp. nebraskensis (Cmn), has reemerged as an important disease of Zea mays (corn) in the U.S. Midwest. Results from a 2011 multistate survey indicated that Setaria spp. (foxtail) were often present in corn fields with a history of Cmn. The objective of this research was to determine if Setaria spp. that are common in the Midwest are susceptible to infection by Cmn. In the greenhouse, seedlings of four Setaria spp., including S. viridis (green foxtail), S. faberi (giant foxtail), S. verticillata (bristly foxtail), and S. pumila (yellow foxtail), and Zea mays …

What’S New In Plant Pathology, Tamra A. Jackson-Ziems, Loren Giesler, Robert M. Harveson, Stephen N. Wegulo, Kevin Korus

Department of Plant Pathology: Faculty Publications

Disease Management Products

During the past year several new products have become available for disease management. The new products are summarized in Tables 1 and 2, as well as included in the 2014 Guide for Weed Management in Nebraska with Insecticide and Fungicide Information. In addition, fungicides labeled for use on sorghum and sunflower have also been added to the publication.

Table 1. New Foliar Fungicides

Table 2. New Seed Nematicide

Disease Identification and Management Resources

Ficotylus Laselvae N. Sp. (Tylenchomorpha: Anguinidae) Associated With Ficus Colubrinae In Costa Rica, Robin M. Giblin-Davis, Natsumi Kanzaki, Kerrie A. Davies, Weimin Ye, Yongsan Zeng, Barbara J. Center, Alejandro Esquivel, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Ficotylus laselvae n. sp. was recovered from under the bracts of figs (syconia) of Ficus colubrinae from La Selva, Costa Rica, during a survey of nematode rainforest biodiversity and is described herein. This is only the second report of an association between the nematode suborder Tylenchina and the sycones of figs. Previous reports of most nematode associates of the sycones of figs have been from the lumen and involved transmission by female fig wasp pollinators (Agaonidae) during pollination/oviposition (e.g., Schistonchus and Parasitodiplogaster spp.). The association between F. laselvae n. sp. and Ficus colubrinae may involve an invertebrate host, …

Wheat Streak Mosaic Virus Infects Systemically Despite Extensive Coat Protein Deletions: Identification Of Virion Assembly And Cell-To-Cell Movement Determinants, Satyanarayana Tatineni, Frank A. Kovacs, Roy C. French

Department of Plant Pathology: Faculty Publications

Viral coat proteins function in virion assembly and virus biology in a tightly coordinated manner with a role for virtually every amino acid. In this study, we demonstrated that the coat protein (CP) of Wheat streak mosaic virus (WSMV; genus Tritimovirus, family Potyviridae) is unusually tolerant of extensive deletions, with continued virion assembly and/or systemic infection found after extensive deletions are made. A series of deletion and point mutations was created in the CP cistron of wild-type and/or green fluorescent protein-tagged WSMV, and the effects of these mutations on cell-to-cell and systemic transport and virion assembly of WSMV …

Phytophthora Ramorum, Sydney E. Everhart, Javier F. Tabima, Niklaus J. Grünwald

Department of Plant Pathology: Faculty Publications

Phytophthora ramorum is a recently emerged plant pathogen and causal agent of one of the most destructive and devastating diseases currently affecting US horticulture and forests (Rizzo et al. 2002, 2005). This oomycete pathogen was discovered in Marin County, California, in the mid-1990s, causing sudden oak death on coast live oak (Quercus agrifolia) and tanoak (Notholithocarpus densiflorus) and simultaneously discovered in Europe causing foliar blight on Rhododendron and Viburnum (Rizzo et al. 2002; Werres et al. 2001). It is now known to affect more than 100 plant species, including economically important nursery and forest host species …

Detection Of Seagrass Scars Using Sparse Coding And Morphological Filter, Ender Oguslu, Sertan Erkanli, Victoria J. Hill, W. Paul Bissett, Richard C. Zimmerman, Jiang Li, Charles R. Bostater Jr. (Ed.), Stelios P. Mertikas (Ed.), Xavier Neyt (Ed.)

OES Faculty Publications

We present a two-step algorithm for the detection of seafloor propeller seagrass scars in shallow water using panchromatic images. The first step is to classify image pixels into scar and non-scar categories based on a sparse coding algorithm. The first step produces an initial scar map in which false positive scar pixels may be present. In the second step, local orientation of each detected scar pixel is computed using the morphological directional profile, which is defined as outputs of a directional filter with a varying orientation parameter. The profile is then utilized to eliminate false positives and generate the final …

Reduced Inputs Turfgrass Through White Clover Inclusion, Bret Andrew Sparks

Theses and Dissertations--Plant and Soil Sciences

Most managed turfgrass species require frequent inputs to maintain an acceptable level of quality. Among these inputs, nitrogen (N) fertilization is usually the most limiting in terms of growth and development. However, N fertilization is also linked to non-point source (NPS) pollution. White clover (WC) is known for its ability to provide N when mixed into stands of turfgrass, and does not pose a threat for NPS pollution. Two field studies were designed to investigate the effects of WC inclusion in stands of cool-season turfgrasses. In the first field study, three cultivation techniques were examined for establishment of WC into …

Boron Nutrition Of Burley And Dark Tobacco, Laura Ann Frakes Mitchell

Theses and Dissertations--Plant and Soil Sciences

The incidences of suspected Boron (B) deficiency have increased recently in Kentucky tobacco fields, potentially due to recent changes in management practices. The symptoms observed in the field include; hollow stalk, stunted growth, deformed or no bud formation, small slits on the lower leaf midrib and uncontrollable breaking of the midrib approximately two inches from the stalk. B is a micronutrient tobacco needs in minute amounts, however excessive additions of B could cause toxicity. The objectives of this work were to 1) establish critical points for B sufficiency, 2) describe and define B deficiency and toxicity symptoms and 3) develop …

Response Of Fusarium Thapsinum To Sorghum Brown Midrib Lines And To Phenolic Metabolites, Deanna L. Funnell-Harris, Scott E. Sattler, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum lines were bred for reduced lignin for cellulosic bioenergy uses, through the incorporation of brown midrib (bmr)6 or -12 into two backgrounds (RTx430 and Wheatland) as either single or doublemutant lines. When these lines were assessed for resistance to Fusarium thapsinum stalk rot, a cause of lodging, they were as resistant to F. thapsinum as the near-isogenic wild type. Peduncles of newly identified bmr lines from an ethyl-methanesulfonate-mutagenized population, inoculated with F. thapsinum, were as resistant as the wild-type line, BTx623. One bmr line (1107) had significantly smaller mean lesion lengths than BTx623, suggesting that a mutation …

Evidence For A Transketolase-Mediated Metabolic Checkpoint Governing Biotrophic Growth In Rice Cells By The Blast Fungus Magnaporthe Oryzae, Jessie Fernandez, Margarita Marroquin-Guzman, Richard A. Wilson

Department of Plant Pathology: Faculty Publications

The blast fungus Magnaporthe oryzae threatens global food security through the widespread destruction of cultivated rice. Foliar infection requires a specialized cell called an appressorium that generates turgor to force a thin penetration hypha through the rice cuticle and into the underlying epidermal cells, where the fungus grows for the first days of infection as a symptomless biotroph. Understanding what controls biotrophic growth could open new avenues for developing sustainable blast intervention programs. Here, using molecular genetics and live-cell imaging, we dismantled M. oryzae glucose-metabolizing pathways to reveal that the transketolase enzyme, encoded by TKL1, plays an essential role …

Identification Of A Sphingolipid Α-Glucuronosyltransferase That Is Essential For Pollen Function In Arabidopsis, Emilie A. Rennie, Berit Ebert, Godfrey P. Miles, Rebecca E. Cahoon, Katy M. Christiansen, Solomon Stonebloom, Hoda Khatab, David Twell, Christopher J. Petzold, Paul D. Adams, Paul Dupree, Joshua L. Heazlewood, Edgar B. Cahoon, Henrik Vibe Scheller

Department of Agronomy and Horticulture: Faculty Publications

Glycosyl inositol phosphorylceramide (GIPC) sphingolipids are a major class of lipids in fungi, protozoans, and plants. GIPCs are abundant in the plasma membrane in plants, comprising around a quarter of the total lipids in these membranes. Plant GIPCs contain unique glycan decorations that include a conserved glucuronic acid (GlcA) residue and various additional sugars; however, no proteins responsible for glycosylating GIPCs have been identified to date. Here, we show that the Arabidopsis thaliana protein INOSITOL PHOSPHORYLCERAMIDE GLUCURONOSYLTRANSFERASE1 (IPUT1) transfers GlcA from UDP-GlcA to GIPCs. To demonstrate IPUT1 activity, we introduced the IPUT1 gene together with genes for a UDP-glucose dehydrogenase …

Dynamics Of Small Rna Profiles Of Virus And Host Origin In Wheat Cultivars Synergistically Infected By Wheat Streak Mosaic Virus And Triticum Mosaic Virus: Virus Infection Caused A Drastic Shift In The Endogenous Small Rna Profile, Satyanarayana Tatineni, Jean-Jack M. Riethoven, Robert A. Graybosch, Roy French, Amitava Mitra

Department of Plant Pathology: Faculty Publications

Co-infection of wheat (Triticum aestivum L.) by Wheat streak mosaic virus (WSMV, a Tritimovirus) and Triticum mosaic virus (TriMV, a Poacevirus) of the family Potyviridae causes synergistic interaction. In this study, the effects of the synergistic interaction between WSMV and TriMV on endogenous and virus-derived small interfering RNAs (vsiRNAs) were examined in susceptible (‘Arapahoe’) and temperature-sensitive resistant (‘Mace’) wheat cultivars at 18 degrees C and 27 degrees C. Single and double infections in wheat caused a shift in the profile of endogenous small RNAs from 24 nt being the most predominant in healthy plants to 21 nt …

Quantification Of Yield Loss Caused By Triticum Mosaic Virus And Wheat Streak Mosaic Virus In Winter Wheat Under Field Conditions, E. Byamukama, S. N. Wegulo, S. Tatineni, G. L. Hein, R. A. Graybosch, P. Stephen Baenziger, R. French

Department of Plant Pathology: Faculty Publications

Triticum mosaic virus (TriMV) and Wheat streak mosaic virus (WSMV) infect winter wheat (Triticum aestivum) in the Great Plains region of the United States. The two viruses are transmitted by wheat curl mites (Aceria tosichella), which also transmit High Plains virus. In a field study conducted in 2011 and 2012, winter wheat cultivars Millennium (WSMV-susceptible) and Mace (WSMV-resistant) were mechanically inoculated with TriMV, WSMV, TriMV+WSMV, or sterile water at the two-leaf growth stage. Chlorophyll meter (soil plant analysis development [SPAD]) readings, area under the SPAD progress curve (AUSPC), grain yield (=yield), yield components (spikes/m², …

Studies On Sensitivity Reduction In Solo And Mixture Treatments And Fungicide-Induced Mutagenesis In Monilinia Fructicola, Guido Schnabel, F. Chen, Sydney E. Everhart, W. C. Bridges, X. Liu

Department of Plant Pathology: Faculty Publications

Three fungicide-sensitive Monilinia fructicola isolates were exposed in weekly transfers of mycelia to a dose gradient of a DMI and a QoI fungicide (azoxystrobin) in solo or mixture treatments and fungicide sensitivity as well as genetic changes were assessed. Isolates showed a faster reduction in sensitivity (higher resistance factors) to azoxystrobin than to SYP-Z048; this process was slower in the mixture treatment. The decrease of fungicide sensitivity was not a heritable trait. Genomic mutagenesis at 8 of 15 microsatellite loci was evidenced in one of three isolates tested after exposure to azoxystrobin. These non-coding regions of the genome either showed …

Methods For Using Cryptococcus Flavescens Strains For Biological Control Of Fusarium Head Blight, Brian B. Mcspadden Gardener, Pierce Anderson Paul, Michael J. Boehm, Xiaoqing Rong, David Schisler

Department of Plant Pathology: Faculty Publications

Disclosed are methods of identifying subspecies of Cryptococcus flavescens and methods of treating or suppressing Fusarium head blight with the different Cryptococcus flavescens species. In particular, two genotypes, Genotypes A and B, were identified using the disclosed real time PCR technique. The following Cryptococcus flavescens strains were identified as being either Genotype A or B and as being able to suppress Fusarium head blight: NRRLY-7373, YB-601, YB-602, Y-7377, Y-7372, Y-7375, Y-7374, Y-7376, YB-328, Y-7379, and YB-744.

Smut Diseases Of Corn, Tamra Jackson-Ziems

Department of Plant Pathology: Faculty Publications

This NebGuide describes the two smut diseases of corn in Nebraska, common smut and head smut, including their symptoms, life cycle, and management.

Two smut diseases of corn occur in Nebraska (Figure 1). Despite their similar appearance, their disease cycles are very different, as are their yield loss potential and management strategies (Table 1).

Common Stalk Rot Diseases Of Corn, Tamra A. Jackson-Ziems, Jennifer M. Rees, Robert M. Harveson

Department of Plant Pathology: Faculty Publications

Extension Circular 1898 (EC1898)

Stalk rot diseases of corn are common, occurring in every field to some extent. Each year stalk rot diseases cause about 5 percent yield loss. Under some conditions, losses can exceed 10–20 percent, and in isolated areas losses have been as high as 100 percent. Stalk rot diseases reduce yield both directly and indirectly. Plants with prematurely rotted stalks produce lightweight, poorly filled ears because of the plant’s limited access to carbohydrates during grain fill. Infected stalks are converted from sturdy, solid rods to hollow tubes as the stalk pith pulls away from the outer rind, …

Disease Profiles: Nematodes Of Nebraska Field Crops, Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1908 (EC1908).

Many species of plant parasitic nematodes affect Nebraska field crops. Some of the more common and/or damaging nematodes are described here. The extent of crop injury depends on the species present, their abundance, and other crop stresses. Diagnosis of nematode injury is difficult because most plant parasitic nematodes can’t be seen with the naked eye and the type and severity of symptoms can vary widely. Most nematodes cause general symptoms that are not diagnostic and may mimic symptoms caused by other biotic or abiotic problems, such as herbicide damage, nutrient imbalances, water stress, and insect feeding. …

Plant Defense Suppression Is Mediated By A Fungal Sirtuin During Rice Infection By Magnaporthe Oryzae, Jessie Fernandez, Margarita Marroquin-Guzman, Renu Nandakumar, Sara Shijo, Kathryn M. Cornwell, Gang Li, Richard Wilson

Department of Plant Pathology: Faculty Publications

Crop destruction by the hemibiotrophic rice pathogen Magnaporthe oryzae requires plant defense suppression to facilitate extensive biotrophic growth in host cells before the onset of necrosis. How this is achieved at the genetic level is not well understood. Here, we report that a M. oryzae sirtuin, MoSir2, plays an essential role in rice defense suppression and colonization by controlling superoxide dismutase (SOD) gene expression. Loss of MoSir2 function in Δsir2 strains did not affect appressorial function, but biotrophic growth in rice cells was attenuated. Compared to wild type, Δsir2 strains failed to neutralize plant-derived reactive oxygen species (ROS) …

A Global Database Of Soil Nematode Abundance And Functional Group Composition, Johan Hoogen, Peter Mullen, 72 Other Scholars

Department of Plant Pathology: Faculty Publications

As the most abundant animals on earth, nematodes are a dominant component of the soil community. They play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into …