Plant Pathology Commons^™

Abiotic And Biotic Factors Affecting The Japanese Beetle In Arkansas, Bryan Mathew Petty

Graduate Theses and Dissertations

Japanese beetles are a relatively new pest to Arkansas. During my Ph.D. research I investigated the pathogens and environmental factors influencing Japanese beetle populations in the state. The prevalence of various pathogens and parasitoids attacking Popillia japonica were recorded annually from wild populations. Of specific interest was the microsporidian pathogen Ovavesicula popilliae, which I introduced as a biological control agent in the state. Details of the relationship between this pathogen and the Japanese beetle were investigated, including dose response, host range, and spore production. Additionally, annual abundance of the beetle in the region was recorded and tracked over the course …

Identification Of Species Of Botryosphaeriaceae Causing Bot Gummosis In Citrus In California, A.O. Adesemoye, J.S. Mayorquin, D.H. Wang, M. Twizeyimana, S.C. Lynch, Akif Eskalen

Department of Plant Pathology: Faculty Publications

Members of the Botryosphaeriaceae family are known to cause Bot gummosis on many woody plants worldwide. To identify pathogens associated with Bot gummosis on citrus in California, scion and rootstock samples were collected in 2010 and 2011 from five citrusgrowing counties in California. Symptoms observed on citrus included branch cankers, dieback, and gumming. Various fungal species were recovered from necrotic tissues of branch canker and rootstock samples. Species were identified morphologically and by phylogenetic comparison as ‘Eureka’ lemon, ‘Valencia’, ‘Washington Navel’, ‘Fukumoto’, grapefruit, ‘Satsuma’, and ‘Meyer’ lemon. Species were identified morphologically and by phylogenetic comparison of the complete sequence of …

Plant Micrornas Display Differential 3' Truncation And Tailing Modifications That Are Argonaute1 Dependent And Conserved Across Species, Jixian Zhai, Yuanyuan Zhao, Stacey A. Simon, Sheng Huang, Katherine Petsch, Siwaret Arikit, Manoj Pillay, Lijuan Ji, Meng Xie, Xiaofeng Cao, Bin Yu, Marja Timmermans, Bing Yang, Xuemei Chen, Blake C. Meyers

Center for Plant Science Innovation: Faculty Publications

Plant small RNAs are 3' methylated by the methyltransferase HUA1 ENHANCER1 (HEN1). In plant hen1 mutants, 3' modifications of small RNAs, including oligo-uridylation (tailing), are associated with accelerated degradation of microRNAs (miRNAs). By sequencing small RNAs of the wild type and hen1 mutants from Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays), we found 39 truncation prior to tailing is widespread in these mutants. Moreover, the patterns of miRNA truncation and tailing differ substantially among miRNA families but are conserved across species. The same patterns are also observable in wild-type libraries from a broad …

Currencies Of Mutualisms: Sources Of Alkaloid Genes In Vertically Transmitted Epichloae, Christopher L. Schardl, Carolyn A. Young, Juan Pan, Simona Florea, Johanna E. Takach, Daniel G. Panaccione, Mark L. Farman, Jennifer S. Webb, Jolanta Jaromczyk, Nikki D. Charlton, Padmaja Nagabhyru, Li Chen, Chong Shi, Adrian Leuchtmann

Plant Pathology Faculty Publications

The epichloae (Epichloë and Neotyphodium species), a monophyletic group of fungi in the family Clavicipitaceae, are systemic symbionts of cool-season grasses (Poaceae subfamily Poöideae). Most epichloae are vertically transmitted in seeds (endophytes), and most produce alkaloids that attack nervous systems of potential herbivores. These protective metabolites include ergot alkaloids and indole-diterpenes (tremorgens), which are active in vertebrate systems, and lolines and peramine, which are more specific against invertebrates. Several Epichloë species have been described which are sexual and capable of horizontal transmission, and most are vertically transmissible also. Asexual epichloae are mainly or exclusively vertically transmitted, and many are …

Initial Fine Mapping Of The Spinach Downy Mildew Resistance Locus Rpf1, Wei Yang

Graduate Theses and Dissertations

Spinach is an important vegetable crop grown in many parts of the world (Correll et al. 2011). It has become increasingly popular due to its nutritional value as it is very high in antioxidants (Prior, 2003). Spinach production, however, is affected by many biotic stresses. Downy mildew, caused by Peronospora farinosa f. sp. spinaciae (Pfs) , is perhaps the most important biotic constraint for spinach production worldwide (Correll et al, 1994). As of 2012, 14 races of Pfs have been reported (Correll et al., 2011). The rapid increase of new races is likely a direct result of substantial changes in …

Morphological And Molecular Taxonomic Identification And Phylogenetics Of Criconematoidea, Marco Cordero

Graduate Theses and Dissertations

The superfamily Criconematoidea has been studied since 1886. It is composed of two families: Criconematidae (subfam. Criconematinae, Hemicycliophorinae) and Tylenchulidae (subfam. Tylenchulinae, Paratylenchinae and Tylenchocriconematinae). Multiple species in genera have been identified and differences and similarities have been found. Species belonging to genera Mesocriconema and Criconemoides show very few differences making their identification difficult. Seventy two populations were studied. They were collected in Arkansas and/or received from the following states: California, Florida, Kansas, Missouri, North Carolina and Tennessee. Populations of the following species were identified: Mesocriconema curvatum, M. kirjanovae, M. onoense, M. ornatum, M. sphaerocephala, M. surinamense, M. vadense, M. …

Evaluation Of Wetland Plants For Susceptibility To Species Of Phytophthora Present In Runoff Water At Ornamental Plant Nurseries, Garrett Ridge

All Theses

Competition between agricultural producers and urban communities for high quality water is increasing; therefore, growers need to adopt water conservation and reuse practices to ensure an adequate supply of irrigation water. One concern with recycled irrigation water is the potential to recirculate propagules of oomycete pathogens. Constructed wetlands are a biologically-based treatment option for nutrient and chemical remediation that potentially also could filter pathogen propagules. The goal of this study was to assess the susceptibility of plants routinely used in constructed wetlands to infection by species of Phytophthora commonly found at ornamental plant nurseries. In laboratory and greenhouse experiments, an …

Uromyces Appendiculatus In Honduras: Pathogen Diversity And Host Resistance Screening, Maricelis Acevedo, James R. Steadman, Juan C. Rosas

Department of Plant Pathology: Faculty Publications

Bean rust, caused by the fungus Uromyces appendiculatus, is a major constraint for common bean production worldwide. Virulence of U. appendiculatus collected from wild and cultivated Phaseolus spp. was examined in 28 locations across Honduras. Host accessions representing wild and domesticated Phaseolus spp. collected at the same sampling locations were evaluated for resistance against U. appendiculatus. In total, 91 pathotypes were identified from 385 U. appendiculatus isolates according to their virulence on each of the 12 host differentials. No significant difference in pathogen total virulence, measured as the mean disease score, was found between locations. However, significant differences …

Puccinia Mariae-Wilsoniae And Claytonia Virginica: A Pathogen's Tale, Sarah A. Schlund

Undergraduate Honors Theses

Rusts are economically important fungal plant pathogens. For the majority of rust species, complete life history data, including host range, geographic distribution, plant response to the rust, identity of alternate hosts, and mode of sexual reproduction are incomplete. The purpose of this study was to examine the life history of Puccinia mariae-wilsoniae, a rust on Claytonia virginica (spring beauty), and to observe responses in leaf anatomy to its fungal pathogen. Spring beauty is an ephemeral woodland plant that lasts three to four weeks and P. mariae-wilsoniae infects C. virginica almost as soon as the plant emerges from dormancy in …

Citrus Tristeza Virus-Host Interactions, W. O. Dawson, S. M. Garnsey, Satyanarayana Tatineni, S. Y. Folimonova, S. J. Harper, S. Gowda

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV) is a phloem-limited virus whose natural host range is restricted to citrus and related species. Although the virus has killed millions of trees, almost destroying whole industries, and continually limits production in many citrus growing areas, most isolates are mild or symptomless in most of their host range. There is little understanding of how the virus causes severe disease in some citrus and none in others. Movement and distribution of CTV differs considerably from that of well-studied viruses of herbaceous plants where movement occurs largely through adjacent cells. In contrast, CTV systemically infects plants mainly by …

Genetic Diversity Of Seed Dormancy And Molecular Evolution Of Weedy Red Rice, Te Ming Tseng

Graduate Theses and Dissertations

Rice is the grain with the third-highest global production. In the US, Arkansas is the largest rice producing state; however, an estimated 62% of the rice fields in the state are infested with red rice, and can cause up to 80% yield reduction in rice. Among its weedy traits, seed dormancy plays an important role in its persistence, and helps red rice escape weed management techniques thereby increasing the red rice soil seedbank. Red rice also has the potential to hybridize among themselves and with cultivated rice, thus resulting in diverse phenotypes and genotypes. In this study we measured variation …

Neofusicoccum Luteum As A Pathogen On Tejocote (Crataegus Mexicana), Anthony O. Adesemoye, Joey S. Mayorquin, Akif Eskalen

Department of Plant Pathology: Faculty Publications

Tejocote (Crataegus mexicana), a small pome crab-apple-like fruit, is becoming economically important in California with increasing production, so consideration of diseases that hinder the yield is important. Diseased trees of tejocote were observed in four orchards of Riverside and San Diego Counties of California. Ten symptomatic/asymptomatic samples were studied from each of the orchards. Five most frequently isolated fungi were identified on the basis of morphological characters and sequence data of the internal transcribed spacer ITS1-5.8SITS2 and partial β-tubulin gene. Three isolates were identified as Neofusicoccum luteum and two as Phomopsis sp. Pathogenicity tests were conducted by inoculating …

Three-Dimensional Structure Of Victorivirus Hvv190s Suggests Coat Proteins In Most Totiviruses Share A Conserved Core, Sarah E. Dunn, Hua Li, Giovanni Cardone, Max L. Nibert, Said A. Ghabrial, Timothy S. Baker

Plant Pathology Faculty Publications

Double-stranded (ds)RNA fungal viruses are currently assigned to six different families. Those from the family Totiviridae are characterized by nonsegmented genomes and single-layer capsids, 300-450 Å in diameter. Helminthosporium victoriae virus 190S (HvV190S), prototype of recently recognized genus Victorivirus, infects the filamentous fungus Helminthosporium victoriae (telomorph: Cochliobolus victoriae), which is the causal agent of Victoria blight of oats. The HvV190S genome is 5179 bp long and encompasses two large, slightly overlapping open reading frames that encode the coat protein (CP, 772 aa) and the RNA-dependent RNA polymerase (RdRp, 835 aa). To our present knowledge, victoriviruses uniquely express their RdRps via …

Brassica Variety Trials 2012, Rebecca Brown

University of Rhode Island Vegetable Production Research Reports

Variety trials of broccoli, cauliflower and Brussels sprouts conducted in Kingston, RI, USA.

Pseudomonas Hopu1 Modulates Plant Immune Receptor Levels By Blocking The Interaction Of Their Mrnas With Grp7, Valerie Nicaise, Anna Joe, Byeong-Ryool Jeong, Christin Korneli, Freddy Boutrot, Isa Westedt, Dorothee Staiger, James R. Alfano, Cyril Zipfel

Center for Plant Science Innovation: Faculty Publications

Pathogens target important components of host immunity to cause disease. The Pseudomonas syringae type III-secreted effector HopU1 is a mono-ADP-ribosyltransferase required for full virulence on Arabidopsis thaliana. HopU1 targets several RNA-binding proteins including GRP7, whose role in immunity is still unclear. Here, we show that GRP7 associates with translational components, as well as with the pattern recognition receptors FLS2 and EFR. Moreover, GRP7 binds specifically FLS2 and EFR transcripts in vivo through its RNA recognition motif. HopU1 does not affect the protein–protein associations between GRP7, FLS2 and translational components. Instead, HopU1 blocks the interaction between GRP7 and FLS2 and …

Small Interfering Rna–Mediated Translation Repression Alters Ribosome Sensitivity To Inhibition By Cycloheximide In Chlamydomonas Reinhardtii, Xinrong Ma, Eun-Jeong Kim, Insun Kook, Fangrui Ma, Adam Voshall, Etsuko N. Moriyama, Heriberto D. Cerutti

Center for Plant Science Innovation: Faculty Publications

Small RNAs (sRNAs; approximately 20 to 30 nucleotides in length) play important roles in gene regulation as well as in defense responses against transposons and viruses in eukaryotes. Their biogenesis and modes of action have attracted great attention in recent years. However, many aspects of sRNA function, such as the mechanism(s) of translation repression at postinitiation steps, remain poorly characterized. In the unicellular green alga Chlamydomonas reinhardtii, sRNAs derived from genomeintegrated inverted repeat transgenes, perfectly complementary to the 39 untranslated region of a target transcript, can inhibit protein synthesis without or with only minimal mRNA destabilization. Here, we report …

Proceedings Of The 40th Annual Meeting, Southern Soybean Disease Workers (March 13-14, 2013, Pensacola Beach, Florida), Clayton A. Hollier, Tom Allen, Edward J. Sikora, Myra Purvis, Danise Beadle, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

Southern United States Soybean Disease Loss Estimates for 2012. Compiled by SR Koenning

Update on Detection and Management of QoI Fungicide Resistant Cercospora sojina, the Causal Agent of Frogeye Leaf Spot in Soybean. C Bradley, G Zhang, V Chapara, R Ming, F Zeng, H Young Kelly, and M Newman

Identification of Soybean Genotypes to Cercopsora sojina by Field Screening and Molecular Markers. A Mengistu and R Mian

Soybean Vein Necrosis Virus. D Hershman

Single Applications of Triazole Fungicides at R1 for Management of Cercospora Leaf Blight and Rust in Soybean. RW Schneider, CL Robertson, BM Ward, and EC …

Plant-Symbiotic Fungi As Chemical Engineers: Multi-Genome Analysis Of The Clavicipitaceae Reveals Dynamics Of Alkaloid Loci, Christopher L. Schardl, Carolyn A. Young, Uljana Hesse, Stefan G. Amyotte, Kalina Andreeva, Patrick J. Calie, Damien J. Fleetwood, David C. Haws, Neil Moore, Birgitt Oeser, Daniel G. Panaccione, Kathryn K. Schweri, Christine R. Voisey, Mark L. Farman, Jerzy W. Jaromczyk, Bruce A. Roe, Donal M. O'Sullivan, Barry Scott, Paul Tudzynski, Zhiqiang An, Elissaveta G. Arnaoudova, Charles T. Bullock, Nikki D. Charlton, Li Chen, Murray Cox, Randy D. Dinkins, Simona Florea, Anthony E. Glenn, Anna Gordon, Ulrich Güldener, Daniel R. Harris, Walter Hollin, Jolanta Jaromczyk, Richard D. Johnson, Anar K. Khan, Eckhard Leistner, Adrian Leuchtmann, Chunjie Li, Jinge Liu, Jinze Liu, Miao Liu, Wade Mace, Caroline Machado, Padmaja Nagabhyru, Juan Pan, Jan Schmid, Koya Sugawara, Ulrike Steiner, Johanna E. Takach, Eiji Tanaka, Jennifer S. Webb, Ella V. Wilson, Jennifer L. Wiseman, Ruriko Yoshida, Zheng Zeng

Plant Pathology Faculty Publications

The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some-including the infamous ergot alkaloids-have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic …

Mites In The Promoters Of Effector Genes Allow Prediction Of Novel Virulence Genes In Fusarium Oxysporum, Sarah M. Schmidt, Petra M. Houterman, Ines Schreiver, Lisong Ma, Stefan G. Amyotte, Biju Chellappan, Sjef Boeren, Frank L. W. Takken, Martijn Rep

Plant Pathology Faculty Publications

BACKGROUND: The plant-pathogenic fungus Fusarium oxysporum f.sp.lycopersici (Fol) has accessory, lineage-specific (LS) chromosomes that can be transferred horizontally between strains. A single LS chromosome in the Fol4287 reference strain harbors all known Fol effector genes. Transfer of this pathogenicity chromosome confers virulence to a previously non-pathogenic recipient strain. We hypothesize that expression and evolution of effector genes is influenced by their genomic context.

RESULTS: To gain a better understanding of the genomic context of the effector genes, we manually curated the annotated genes on the pathogenicity chromosome and identified and classified transposable elements. Both retro- and DNA transposons are present …

The Voltage-Sensing Domain Of A Phosphatase Gates The Pore Of A Potassium Channel, Cristina Arrigoni, Indra Schroeder, Giulia Romani, James L. Van Etten, Gerhard Thiel, Anna Moroni

James Van Etten Publications

The modular architecture of voltage-gated K⁺ (Kv) channels suggests that they resulted from the fusion of a voltage-sensing domain (VSD) to a pore module. Here, we show that the VSD of Ciona intestinalis phosphatase (Ci-VSP) fused to the viral channel Kcv creates Kv_Synth1, a functional voltage-gated, outwardly rectifying K⁺ channel. Kv_Synth1 displays the summed features of its individual components: pore properties of Kcv (selectivity and filter gating) and voltage dependence of Ci-VSP (V1/2 = +56 mV; z of approx. 1), including the depolarizationinduced mode shift. The degree of outward rectification of the channel is critically …