Plant Pathology Commons^™

Engineering Of A Light-Gated Potassium Channel, Christian Cosentino, Laura Alberio, Sabrina Gazzarrini, Marco Aquila, Eduardo Romano, Solei Cermenati, Paolo Zuccolini, Jan Petersen, Monica Beltrame, James L. Van Etten, John M. Christie, Gerhard Thiel, Anna Moroni

James Van Etten Publications

The present palette of opsin-based optogenetic tools lacks a light-gated potassium (K+) channel desirable for silencing of excitable cells. Here, we describe the construction of a blue-light–induced K+ channel 1 (BLINK1) engineered by fusing the plant LOV2-Ja photosensory module to the small viral K+ channel Kcv. BLINK1 exhibits biophysical features of Kcv, including K+ selectivity and high single-channel conductance, but reversibly photoactivates in blue light. Opening of BLINK1 channels hyperpolarizes the cell to the K+ equilibrium potential. Ectopic expression of BLINK1 reversibly inhibits the escape response in light-exposed zebrafish larvae. BLINK1 therefore provides a single-component optogenetic tool that can establish …

Genetics, Genomics And Evolution Of Ergot Alkaloid Diversity, Carolyn A. Young, Christopher L. Schardl, Daniel G. Panaccione, Simona Florea, Johanna E. Takach, Nikki D. Charlton, Neil Moore, Jennifer S. Webb, Jolanta Jaromczyk

Plant Pathology Faculty Publications

The ergot alkaloid biosynthesis system has become an excellent model to study evolutionary diversification of specialized (secondary) metabolites. This is a very diverse class of alkaloids with various neurotropic activities, produced by fungi in several orders of the phylum Ascomycota, including plant pathogens and protective plant symbionts in the family Clavicipitaceae. Results of comparative genomics and phylogenomic analyses reveal multiple examples of three evolutionary processes that have generated ergot-alkaloid diversity: gene gains, gene losses, and gene sequence changes that have led to altered substrates or product specificities of the enzymes that they encode (neofunctionalization). The chromosome ends appear to be …

Disparate Independent Genetic Events Disrupt The Secondary Metabolism Gene Pera In Certain Symbiotic Epichloë Species, Daniel Berry, Johanna E. Takach, Christopher L. Schardl, Nikki D. Charlton, Barry Scott, Carolyn A. Young

Plant Pathology Faculty Publications

Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C₃ grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase …

Functional Analysis Of Genes Involved In Response To Sheath Blight Disease Using Virus-Induced Gene Silencing, Elaf Osamaho Mohammed Ali

Theses and Dissertations

Phytotoxins (RS toxin) play a crucial role in the virulence of the necrotrophic phytopathogenic Rhizoctonia solani. This pathogen is highly invasive and has an extremely wide host range that causes economic loss, moreover, this pathogen is both soil- and water-borne and can produce lesion symptoms that rapidly develop into a disease known as sheath blight disease. Susceptibility to this disease and sensitivity to phytotoxins depend on the plant's ability to defend itself against the pathogen attack and induce an active defense mechanism. There are several genes-candidates that have been suggested as possible host-plant sensitivity genes associated with R. solani infection. …

In Vivo Localization Of Iris Yellow Spot Tospovirus (Bunyaviridae)-Encoded Proteins And Identification Of Interacting Regions Of Nucleocapsid And Movement Proteins, Diwaker Tripathi, Gaurav Raikhy, Michael M. Goodin, Ralf G. Dietzgen, Hanu R. Pappu

Plant Pathology Faculty Publications

BACKGROUND: Localization and interaction studies of viral proteins provide important information about their replication in their host plants. Tospoviruses (Family Bunyaviridae) are economically important viruses affecting numerous field and horticultural crops. Iris yellow spot virus (IYSV), one of the tospoviruses, has recently emerged as an important viral pathogen of Allium spp. in many parts of the world. We studied the in vivo localization and interaction patterns of the IYSV proteins in uninfected and infected Nicotiana benthamiana and identified the interacting partners.

PRINCIPAL FINDINGS: Bimolecular fluorescence complementation (BiFC) analysis demonstrated homotypic and heterotypic interactions between IYSV nucleocapsid …

Reply To Kjartansdóttir Et Al.: Chlorovirus Atcv-1 Findings Not Explained By Contamination, Robert H. Yolken, Lorraine Jones-Brando, David Dunigan, Geetha Kannan, Faith Dickerson, Emily Severance, Sarven Sabunciyan, C. Conover Talbot Jr., Emese Prandovszky, James Gurnon, Irina Agarkova, Flora Leister, Kristin L. Gressitt, Ou Chen, Bryan Deuber, Fangrui Ma, Mikhail V. Pletnikov, James L. Van Etten

James Van Etten Publications

We agree with Kjartansdóttir et al. (1) that extreme caution must be used when interpreting high-throughput sequencing results in new hosts. The situation demands thorough investigation and validation beyond the identification of a few sequencing reads. However, we believe it is unlikely that random laboratory contamination explains the results reported in Yolken et al. (2) for the following reasons. ...

Therefore, the conclusions in our report are based not only on “a few sequence reads” (1), but on confirmatory assays, as well as a highly controlled animal model of oral exposure and subsequent measurement of immune response and behavior. We …

Sumoylation By A Stress-Specific Small Ubiquitin-Like Modifier E2 Conjugase Is Essential For Survival Of Chlamydomonas Reinhardtii Under Stress Conditions, Amy R. Knobbe, Kempton M. Horken, Thomas M. Plucinak, Eniko Balassa, Heriberto Cerutti, Donald P. Weeks

Center for Plant Science Innovation: Faculty Publications

Posttranslational modification of proteins by small ubiquitin-like modifier (SUMO) is required for survival of virtually all eukaryotic organisms. Attachment of SUMO to target proteins is catalyzed by SUMO E2 conjugase. All haploid or diploid eukaryotes studied to date possess a single indispensable SUMO conjugase. We report here the unanticipated isolation of a Chlamydomonas reinhardtii (mutant5 [mut5]), in which the previously identified SUMO conjugase gene C. reinhardtii ubiquitin-conjugating enzyme9 (CrUBC9) is deleted. This surprising mutant is viable and unexpectedly displays a pattern of protein SUMOylation at 25°C that is essentially identical to wild-type cells. However, unlike wild-type …

Proceedings Of The 42nd Annual Meeting, Southern Soybean Disease Workers (March 11-12, 2015, Pensacola Beach, Florida), Craig Rothrock, Ed Sikora, Trey Price, Danise Beadle, Myra Purvis, Tom Allen, Loren Giesler

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United States Soybean Disease Loss Estimates for 2014. TW Allen, JP Damicone, NS Dufault, TR Faske, DE Hershman, CA Hollier, T Isakeit, RC Kemerait, NM Kleczewski, SR Koenning, HL Mehl, JD Mueller, C Overstreet, P Price, EJ Sikora, and H Young

Graduate student competition (Trey Price, moderator)

Effect of Secondary Nutrient Applications on Suppression of Charcoal Rot in Soybean. T Wilkerson, M Tomasu-Peterson, BR Golden, S Lu, AB Johnson, and TW Allen

Molecular Characterization of the G143A Mutation Leading to QoI Fungicide Resistance among Fungal Pathogens Causing Cercospora Leaf Blight and Purple Seed Stain of Soybean. S …

The Proteasomal Rpn11 Metalloprotease Suppresses Tombusvirus Rna Recombination And Promotes Viral Replication Via Facilitating Assembly Of The Viral Replicase Complex, K. Reddisiva Prasanth, Daniel Barajas, Peter D. Nagy

Plant Pathology Faculty Publications

RNA viruses co-opt a large number of cellular proteins that affect virus replication and, in some cases, viral genetic recombination. RNA recombination helps viruses in an evolutionary arms race with the host's antiviral responses and adaptation of viruses to new hosts. Tombusviruses and a yeast model host are used to identify cellular factors affecting RNA virus replication and RNA recombination. In this study, we have examined the role of the conserved Rpn11p metalloprotease subunit of the proteasome, which couples deubiquitination and degradation of proteasome substrates, in tombusvirus replication and recombination in Saccharomyces cerevisiae and plants. Depletion or mutations of Rpn11p …

Coordinated Function Of Cellular Dead-Box Helicases In Suppression Of Viral Rna Recombination And Maintenance Of Viral Genome Integrity, Chingkai Chuang, K. Reddisiva Prasanth, Peter D. Nagy

Plant Pathology Faculty Publications

The intricate interactions between viruses and hosts include an evolutionary arms race and adaptation that is facilitated by the ability of RNA viruses to evolve rapidly due to high frequency mutations and genetic RNA recombination. In this paper, we show evidence that the co-opted cellular DDX3-like Ded1 DEAD-box helicase suppresses tombusviral RNA recombination in yeast model host, and the orthologous RH20 helicase functions in a similar way in plants. In vitro replication and recombination assays confirm the direct role of the ATPase function of Ded1p in suppression of viral recombination. We also present data supporting a role for Ded1 in …

Novel Mechanism Of Regulation Of Tomato Bushy Stunt Virus Replication By Cellular Ww-Domain Proteins, Daniel Barajas, Nikolay Kovalev, Jun Qin, Peter D. Nagy

Plant Pathology Faculty Publications

Replication of (+)RNA viruses depends on several co-opted host proteins but is also under the control of cell-intrinsic restriction factors (CIRFs). By using tombusviruses, small model viruses of plants, we dissect the mechanism of inhibition of viral replication by cellular WW-domain-containing proteins, which act as CIRFs. By using fusion proteins between the WW domain and the p33 replication protein, we show that the WW domain inhibits the ability of p33 to bind to the viral RNA and to other p33 and p92 replication proteins leading to inhibition of viral replication in yeast and in a cell extract. Overexpression of WW-domain …

The Effects Of Fungicides And Regalia Tank Mixtures On Fray Leaf Spot In Nebraska Field Corn, 2014, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare industry fungicide programs with the microbial Regalia Rx plus fungicide tank mixtures for gray leaf spot (GLS) efficacy. Corn was grown under normal, irrigated agronomic practices at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % organic matter. Reduced tillage was performed to the field prior to planting. Corn (DKC 64-83 RIB, moderately susceptible to GLS) was planted at approximately 34,000 seed/A on 20 May. Seven treatments were arranged in a randomized complete block design with six replications. . . . …

Fungicide-Induced Transposon Movement In Monilinia Fructicola, Fengping Chen, Sydney E. Everhart, P. Karen Bryson, Chaoxi Luo, Xi Song, Xili Liu, Guido Schnabel

Department of Plant Pathology: Faculty Publications

Repeated applications of fungicides with a single mode of action are believed to select for pre-existing resistant strains in a pathogen population, while the impact of sub-lethal doses of such fungicides on sensitive members of the population is unknown. In this study, in vitro evidence is presented that continuous exposure of Monilinia fructicola mycelium to some fungicides can induce genetic change in form of transposon transposition. Three fungicide-sensitive M. fructicola isolates were exposed in 12 weekly transfers of mycelia to a dose gradient of demethylation inhibitor fungicide (DMI) SYP-Z048 and quinone outside inhibitor fungicide (QoI) azoxystrobin in solo or mixture …

Effect Of Y-Trellis And Vertical Shoot Positioning Training Systems On Downy Mildew And Botrytis Bunch Rot Of Grape In Highlands Of Southern Brazil, Betina Pereira De Bem, Amauri Bogo, Sydney Everhart, Ricardo Trezzi Casa, Mayra Juline Gonçalves, José Luiz Marcon Filho, Isabel Cristina Da Cunha

Department of Plant Pathology: Faculty Publications

Downy mildew (Plasmopara viticola) and botrytis bunch rot (Botrytis cinerea) are important diseases in the highlands of Santa Catarina State, a relatively new wine-growing region in Brazil. Although it is known that training systems can affect microclimate and subsequent disease development, this has not been examined in the highlands of Brazil. Thus, the purpose of this study was to evaluate the influence of Y-trellis (YT) and vertical shoot positioning (VSP) training system on downy mildew and botrytis bunch rot disease development in “Cabernet Sauvignon” cultivar. Experiments were carried out in commercial vineyards in São Joaquim, SC …

Weather Variability And Disease Management Strategies, Kevin Korus, Tony O. Adesemoye, Loren Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

This year’s title of “weather variability and disease management strategies” was chosen because we need to remember how weather conditions this year have impacted crop productivity and disease development. This will enable us to look forward and develop better management decisions for future growing seasons. Agricultural production is dependent on many climatic factors such as rain, humidity, temperature, and sunlight. These climate conditions have direct effects on yield as well as other indirect effects. One specific indirect effect of extreme weather events is increased pressure from pathogens and pests. Plant pathogens are commonly favored by very specific, and sometimes extreme, …

Toward Production Of Jet Fuel Functionality In Oilseeds: Identification Of Fatb Acyl-Acyl Carrier Protein Thioesterases And Evaluation Of Combinatorial Expression Strategies In Camelina Seeds, Hae Jin Kim, Jillian E. Silva, Hieu Sy Vu, Keithanne Mockaitis, Jeong-Won Nam, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Seeds of members of the genus Cuphea accumulate medium-chain fatty acids (MCFAs; 8:0–14:0). MCFA- and palmitic acid- (16:0) rich vegetable oils have received attention for jet fuel production, given their similarity in chain length to Jet A fuel hydrocarbons. Studies were conducted to test genes, including those from Cuphea, for their ability to confer jet fuel-type fatty acid accumulation in seed oil of the emerging biofuel crop Camelina sativa. Transcriptomes from Cuphea viscosissima and Cuphea pulcherrima developing seeds that accumulate >90% of C8 and C10 fatty acids revealed three FatB cDNAs (CpuFatB3, CvFatB1, and CpuFatB4 …

Fungal Morphogenesis, Xiaorong Lin, J. Andrew Alspaugh, Haoping Liu, Steven D. Harris

Center for Plant Science Innovation: Faculty Publications

Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and …

Gene Silencing In Microalgae: Mechanisms And Biological Roles, Eun-Jeong Kim, Xinrong Ma, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Microalgae exhibit enormous diversity and can potentially contribute to the production of biofuels and high value compounds. However, for most species, our knowledge of their physiology, metabolism, and gene regulation is fairly limited. In eukaryotes, gene silencing mechanisms play important roles in both the reversible repression of genes that are required only in certain contexts and the suppression of genome invaders such at transposons. The recent sequencing of several algal genomes is providing insights into the complexity of these mechanisms in microalgae. Collectively, glaucophyte, red, and green microalgae contain the machineries involved in repressive histone H3 lysine methylation, DNA cytosine …

Sirna-Directed Dna Methylation In Plants, Meng Xie, Bin Yu

Center for Plant Science Innovation: Faculty Publications

DNA cytosine methylationis an important epigenetic process that is correlated with transgene silencing, transposon suppression, and gene imprinting. In plants, small interfering RNAs (siRNAs) can trigger DNA methylation at loci containing their homolog sequences through a process called RNAdirected DNA methylation (RdDM). In canonical RdDM, 24 nucleotide (nt) siRNAs (ra-siRNAs) will be loaded into their effector protein called ARGONAUTE 4 (AGO4) and subsequently targeted to RdDM loci through base-pairing with the non-coding transcripts produced by DNA-directed RNA Polymerase V. Then, the AGO4-ra-siRNA will recruit the DNA methyltransferase to catalyze de novo DNA methylation. Recent studies also identified non-canonical RdDM pathways …

The Role Of Ethylene In Plant Responses To K+ Deficiency, Daniel P. Schachtman

Center for Plant Science Innovation: Faculty Publications

Potassium is an essential macronutrient that is involved in regulating turgor , in driving plant growth, and in modulating enzyme activation. The changes in root morphology, root function, as well as cellular and molecular responses to low potassium conditions have been studied in the model plant Arabidopsis and in other plant species. In Arabidopsis ethylene plays a key role in roots in the transduction of the low potassium signal, which results in altered root function and growth. The first clues regarding the role of ethylene were detected through transcriptional profiling experiments showing changes in the expression of genes related to …