Plant Pathology Commons^™

The Chlorella Variabilis Nc64a Genome Reveals Adaptation To Photosymbiosis, Coevolution With Viruses, And Cryptic Sex, Guillaume Blanc, Garry Duncan, Irina Agarkova, Mark Borodovsky, James Gurnon, Alan Kuo, Erika Lindquist, Susan Lucas, Jasmyn Pangilinan, Juergen Polle, Asaf Salamov, Astrid Terry, Takashi Yamada, David D. Dunigan, Igor V. Grigoriev, Jean-Michel Claverie, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Chlorella variabilis NC64A, a unicellular photosynthetic green alga (Trebouxiophyceae), is an intracellular photobiont of Paramecium bursaria and a model system for studying virus/algal interactions. We sequenced its 46-Mb nuclear genome, revealing an expansion of protein families that could have participated in adaptation to symbiosis. NC64A exhibits variations in GC content across its genome that correlate with global expression level, average intron size, and codon usage bias. Although Chlorella species have been assumed to be asexual and nonmotile, the NC64A genome encodes all the known meiosis-specific proteins and a subset of proteins found in flagella. We hypothesize that Chlorella might have …

Increased Plant Uptake Of Nitrogen From 15N-Depleted Fertilizer Using Plant Growth-Promoting Rhizobacteria, A. O. Adesemoye, H. A. Torbert, J. W. Kloepper

Department of Plant Pathology: Faculty Publications

Harmful environmental effects resulting from fertilizer use have spurred research into integrated nutrient management strategies which can include the use of specific microorganisms to enhance nutrient use efficiency by plants. Some strains of plant growth-promoting rhizobacteria (PGPR) have been reported to enhance nutrient uptake by plants, but no studies with PGPR have used ¹⁵N isotope techniques to prove that the increased N in plant tissues came from the N applied as fertilizer. The current study was conducted to demonstrate that a model PGPR system can enhance plant uptake of fertilizer N applied to the soil using different rates of …

Unique Functionality Of 22 Nt Mirnas In Triggering Rdr6-Dependent Sirna Biogenesis From Target Transcripts In Arabidopsis, Josh T. Cuperus, Alberto Carbonell, Noah Fahlgren, Hernan Garcia-Ruiz, Russell T. Burke, Atsushi Takeda, Christopher M. Sullivan, Sunny D. Gilbert, Taiowa A. Montgomery, James C. Carrington

Department of Plant Pathology: Faculty Publications

RNA interference pathways may involve amplification of secondary siRNAs by RNA-dependent RNA polymerases. In plants, RDR6-dependent secondary siRNAs arise from transcripts targeted by some microRNA (miRNA). Here, Arabidopsis thaliana secondary siRNA from mRNA, and trans-acting siRNA, are shown to be triggered through initial targeting by 22 nt miRNA that associate with AGO1. In contrast to canonical 21 nt miRNA, 22 nt miRNA primarily arise from foldback precursors containing asymmetric bulges. Using artificial miRNA constructs, conversion of asymmetric foldbacks to symmetric foldbacks resulted in production of 21 nt forms of miR173, miR472 and miR828. Both 21 and 22 nt forms associated …

Heterokaryotic Nuclear Conditions And A Heterogeneous Nuclear Population Are Observed By Flow Cytometry In Phytophthora Infestans, Mursel Catal, Louis King, Pavani Tumbalam, Prissana Wiriyajitsomboon, William W. Kirk, Gerard C. Adams

Department of Plant Pathology: Faculty Publications

A simple and reliable method for preparation of whole nuclei of a common oomycete, Phytophthora infestans, is described for laser flow cytometry. The ease of preparation, the absence of detectable debris and aggregates, and the precision in determinations of DNA content per nucleus improve interpretation and understanding of the genetics of the organism. Phytophthora infestans is the pathogen that causes potato and tomato late blight. The genetic flexibility of P. infestans and other oomycete pathogens has complicated understanding of the mechanisms of variation contributing to shifts in race structure and virulence profiles on important agricultural crops. Significant phenotypic and …

Alteration In Lignin Biosynthesis Restricts Growth Of Fusarium Spp. In Brown Midrib Sorghum, Deanna L. Funnell-Harris, Jeffrey F. Pedersen, Scott E. Sattler

Department of Plant Pathology: Faculty Publications

To improve sorghum for bioenergy and forage uses, brown midrib (bmr)6 and -12 near-isogenic genotypes were developed in different sorghum backgrounds. The bmr6 and bmr12 grain had significantly reduced colonization by members of the Gibberella fujikuroi species complex compared with the wild type, as detected on two semiselective media. Fusarium spp. were identified using sequence analysis of a portion of the translation elongation factor (TEF) 1-α gene. The pathogens Fusarium thapsinum, F. proliferatum, and F. verticillioides, G. fujikuroi members, were commonly recovered. Other frequently isolated Fusarium spp. likely colonize sorghum asymptomatically. The χ2 analyses showed that the …

A Functional Calcium-Transporting Atpase Encoded By Chlorella Viruses, Maria Cristina Bonza, Holger Martin, Ming Kang, Gentry L. Lewis, Timo Greiner, Sonia Giacometti, James L. Van Etten, Maria Ida De Michelis, Gerhard Thiel, Anna Moroni

James Van Etten Publications

Calcium-transporting ATPases (Ca²⁺ pumps) are major players in maintaining calcium homeostasis in the cell and have been detected in all cellular organisms. Here, we report the identification of two putative Ca²⁺ pumps, M535L and C785L, encoded by chlorella viruses MT325 and AR158, respectively, and the functional characterization of M535L. Phylogenetic and sequence analyses place the viral proteins in group IIB of P-type ATPases even though they lack a typical feature of this class, a calmodulin-binding domain. A Ca²⁺ pump gene is present in 45 of 47 viruses tested and is transcribed during virus infection. Complementation analysis of …

Identification Of An L-Rhamnose Synthetic Pathway In Two Nucleocytoplasmic Large Dna Viruses, Madhu Parakkottil Chothi, Garry A. Duncan, Andrea Armirotti, Chantal Abergel, James R. Gurnon, James L. Van Etten, Cinzia Bernardi, Gianluca Damonte, Michela Tonetti

James Van Etten Publications

Nucleocytoplasmic large DNA viruses (NCLDVs) are characterized by large genomes that often encode proteins not commonly found in viruses. Two species in this group are Acanthocystis turfacea chlorella virus 1 (ATCV-1) (family Phycodnaviridae, genus Chlorovirus) and Acanthamoeba polyphaga mimivirus (family Mimiviridae), commonly known as mimivirus. ATCV-1 and other chlorovirus members encode enzymes involved in the synthesis and glycosylation of their structural proteins. In this study, we identified and characterized three enzymes responsible for the synthesis of the sugar L-rhamnose: two UDP-D-glucose 4,6-dehydratases (UGDs) encoded by ATCV-1 and mimivirus and a bifunctional UDP-4-keto-6-deoxy-D-glucose epimerase/reductase (UGER) from mimivirus. Phylogenetic …

Overall Growth Of Tomato (Lycopersicon Esculentum L. Cv. Glacier) Inoculated With Species Of Glomus And Trichoderma Growing Under Greenhouse Conditions, Brian J. Adkins

Horticulture and Crop Science

The overall plant growth of tomato (Lycopersicon esculentum L. cv. Glacier) cultivated in greenhouse conditions along with inoculation treatments of beneficial fungi species were observed. This study included 2 brand name products containing species of fungi which include: 1)Botanicare Guardian TR containing Trichoderma harzianum 10,000,000 CFU/g, T. hamatum 10,000,000 CFU/g, T. koningii 10,000,000 CFU/g; and 2)Botanicare Guardian MY containing Glomus intraradices 57 propagules/g;G. fasiculatum 57 propagules/g; G. etunicatum 57 propagules/g; G. clarum 57 propagules/g. Treatments include: Treatments: 1) 2g Botanicare Guardian TR; 2) 2g Botanicare Guardian MY; 3) 1g Botanicare Guardian TR + 1g Botanicare Guardian MY; and …

Fragaria Species Grown In A Greenhouse Cropping System Chemigated By Phosfite® And Bacillus® In Subsidence Of Phytophthora Fragariae And Verticillium Dahliae, Russell L. Morgan

Earth and Soil Sciences

Strawberry yields depend directly on infestation of Phytophthora fragariae and Verticillium dahliae in correspondance to the use of Phosfite and Bacillus. The objective is to find understanding of newly administered techniques in prevention of Phytophthora fragariae and Verticillium dahliae and prohibiting the use of Methyl Bromide. Application of Phosfite and Bacillus on patented Fragariae species to identify utilization of P and ZN forms and their aid in prevention of Phytophthora and Verticillium species. In the Plots on the western bench the developmental symptoms of PRR disease were absent within all infested soil containers containing the FHS-1 crop. In the plots …

Environmental Variables Influencing The Severity Of Pierce's Disease In California Grapevines, Christopher James Boisseranc

Master's Theses

This project was designed to correlate environmental variables with the development of Pierce’s Disease (PD), an infection caused by the gram negative bacterium Xylella fastidiosa (Xf), in grapes (Hopkins et al. 2002). PD is one of the most difficult crop pathogens to manage because it is vectored by insects and its continued presence in the vine is usually fatal. PD is influenced by the interaction of host, disease and vector, and probably many other environmental variables. The general objective was to study and identify the most important variables involved in the expression of Pierce’s Disease.

Over a two year period, …

Vittatidera Zeaphila (Nematoda: Heteroderidae), A New Genus And Species Of Cyst Nematode Parasitic On Corn (Zea Mays), Ernest C. Bernard, Zafar A. Handoo, Thomas O. Powers, Patricia A. Donald, Robert D. Heinz

Department of Plant Pathology: Faculty Publications

A new genus and species of cyst nematode, Vittatidera zeaphila, is described from Tennessee. The new genus is superficially similar to Cactodera but is distinguished from other cyst-forming taxa in having a persistent lateral field in females and cysts, persistent vulval lips covering a circumfenestrate vulva, and subventral gland nuclei of the female contained in a separate small lobe. Infective juveniles (J2) are distinguished from all previously described Cactodera spp. by the short stylet in the second-stage juvenile (14-17 mm); J2 of Cactodera spp. have stylets at least 18 mm long. The new species also is unusual in that …

Origin Of The Polycomb Repressive Complex 2 And Gene Silencing By An E(Z) Homolog In The Unicellular Alga Chlamydomonas, Scott Shaver, J. Armando Casas-Mollano, Ronald L. Cerny, Heriberto D. Cerutti

Center for Plant Science Innovation: Faculty Publications

Polycomb group proteins play an essential role in the maintenance of cell identity and the regulation of development in both animals and plants. The Polycomb Repressive Complex 2 (PRC2) is involved in the establishment of transcriptionally silent chromatin states, in part through its ability to methylate lysine 27 of histone H3 by the Enhancer of zeste [E(z)] subunit. The absence of PRC2 in unicellular model fungi and its function in the repression of genes vital for the development of higher eukaryotes led to the proposal that this complex may have evolved together with the emergence of multicellularity. However, we report …

Dna Viruses: The Really Big Ones (Giruses), James L. Van Etten, Leslie C. Lane, David Dunigan

Department of Plant Pathology: Faculty Publications

Viruses with genomes greater than 300 kb and up to 1200 kb are being discovered with increasing frequency. These large viruses (often called giruses) can encode up to 900 proteins and also many tRNAs. Consequently, these viruses have more protein-encoding genes than many bacteria, and the concept of small particle/small genome that once defined viruses is no longer valid. Giruses infect bacteria and animals although most of the recently discovered ones infect protists. Thus, genome gigantism is not restricted to a specific host or phylogenetic clade. To date, most of the giruses are associated with aqueous environments. Many of these …

A Potential Plan Of Action For Emerald Ash Borer In Nebraska, Lee Wheeler

Department of Environmental Studies: Undergraduate Student Theses

Abstract Emerald Ash Borer (Agrilus planipennis) (EAB) is an invasive insect pest. It feeds on the cambium tissues of ash tree species. It was first discovered in the United States in 2002 in Detroit, Michigan. Their effects on ash trees are deadly, and it is quickly spreading across the Midwest. Nebraska has not yet been invaded, but confirmed findings continue getting closer and closer. The major problem facing Nebraskans, with regards to EAB, is how to begin preparations to prevent a dramatic economic loss when an infestation does occur. So, to address this problem, I have conducted street and park …

Distinct Evolutionary Histories Of The Dna-A And Dna-B Components Of Bipartite Begomoviruses, Rob W. Briddon, Basavaprabhu L. Patil, Basavaraj Bagewadi, Muhammad Shah Nawaz-Ul-Rehman, Claude M. Fauquet

Plant Pathology Faculty Publications

BACKGROUND: Viruses of the genus Begomovirus (family Geminiviridae) have genomes consisting of either one or two genomic components. The component of bipartite begomoviruses known as DNA-A is homologous to the genomes of all geminiviruses and encodes proteins required for replication, control of gene expression, overcoming host defenses, encapsidation and insect transmission. The second component, referred to as DNA-B, encodes two proteins with functions in intra- and intercellular movement in host plants. The origin of the DNA-B component remains unclear. The study described here was initiated to investigate the relationship between the DNA-A and DNA-B components of bipartite begomoviruses with a …

The Pseudomonas Syringae Type Iii Effector Hopg1 Targets Mitochondria, Alters Plant Development, And Suppresses Plant Innate Immunity, Anna Block, Ming Guo, Guangyong Li, Christian Elowsky, Thomas Clemente, James R. Alfano

Center for Plant Science Innovation: Faculty Publications

The bacterial plant pathogen Pseudomonas syringae uses a type III protein secretion system to inject type III effectors into plant cells. Primary targets of these effectors appear to be effector-triggered immunity (ETI) and pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). The type III effector HopG1 is a suppressor of ETI that is broadly conserved in bacterial plant pathogens. Here we show that HopG1 from P. syringae pv. tomato DC3000 also suppresses PTI. Interestingly, HopG1 localizes to plant mitochondria, suggesting that its suppression of innate immunity may be linked to a perturbation of mitochondrial function. While HopG1 possesses no obvious mitochondrial signal …

Alkylresorcinol Synthases Expressed In Sorghum Bicolor Root Hairs Play An Essential Role In The Biosynthesis Of The Allelopathic Benzoquinone Sorgoleone, Daniel Cook, Agnes M. Rimando, Thomas E. Clemente, Joachim Schroder, Franck E. Dayan, N. P. Dhammika Nanayakkara, Zhiqiang Pan, Brice P. Noonan, Mark Fishbein, Ikuro Abe, Stephen O. Duke, Scott R. Baerson

Center for Plant Science Innovation: Faculty Publications

Sorghum bicolor is considered to be an allelopathic crop species, producing phytotoxins such as the lipid benzoquinone sorgoleone, which likely accounts for many of the allelopathic properties of Sorghum spp. Current evidence suggests that sorgoleone biosynthesis occurs exclusively in root hair cells and involves the production of an alkylresorcinolic intermediate (5-[(Z,Z)-8',11',14'-pentadecatrienyl]resorcinol) derived from an unusual 16:3D^9,12,15 fatty acyl-CoA starter unit. This led to the suggestion of the involvement of one or more alkylresorcinol synthases (ARSs), type III polyketide synthases (PKSs) that produce 5-alkylresorcinols using medium to long-chain fatty acyl-CoA starter units via iterative condensations with malonyl-CoA. In an effort …

Proceedings Of The 37th Annual Meeting, Southern Soybean Disease Workers (March 10-11, 2010, Pensacola Beach, Florida), Jason Bond, Boyd Padgett, Clayton A. Hollier, Alemu Mengistu, Cliff Coker, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

SSDW treasury report

Southern United States Soybean Disease Loss Estimates for 2009. Compiled by SR Koenning

Green Bean symposium (Jason Bond, moderator)

Factors Contributing to Green Plants at Maturity. DJ Boquet, RL Leonard, GB Padgett, RW Schneider, J Griffin, J Davis, and R Vaverde

The Green Stem Disorder Enigma in Illinois. C Hill and G. Hartman

The Influence of Fungicides, Herbicides, and Their Interactions on Green Bean Syndrome. GB Padgett, DJ Boquet, RW Schneider, and MA Purvis

Association of Stink Bug Injury with A "Green Plant" Malady in Soybean. JH Temple, BR Leonard, J Davis, P Price, and J …

Wheat Cultivar-Specific Disease Synergism And Alteration Of Virus Accumulation During Co-Infection With Wheat Streak Mosaic Virus And Triticum Mosaic Virus, Satyanarayana Tatineni, Robert A. Graybosch, Gary L. Hein, Stephen N. Wegulo, Roy French

Department of Plant Pathology: Faculty Publications

Triticum mosaic virus (TriMV), the type member of the newly proposed Poacevirus genus, and Wheat streak mosaic virus (WSMV), the type member of Tritimovirus genus of the family Potyviridae, infect wheat naturally in the Great Plains and are transmitted by wheat curl mites. In this study, we examined the ability of these viruses to infect selected cereal hosts, and found several differential hosts between TriMV and WSMV. Additionally, we examined the interaction between WSMV and TriMV in three wheat cultivars at two temperature regimens (19 and 20 to 26°C), and quantified the virus concentration in single and double infections …

Crop Updates 2010 - Crop Specific, Hugh J. Beckie, Wallace Cowling, T. N. Khan, K. Adhikari, K. Siddique, J. Garlinge, L. Smith, S. Morgan, C. Boyd, Ian Pritchard, Chris Veitch, Alan Harris, Tony Leonforts, Murray Blyth, Shari Dougal, Kristy Hobson, Ben Curtis, Doug Sawkins, D. Stephens, Ciara Beard, Kith Jayasena, Kazue Tanaka, Anne Smith, Brenda Coutts, Roger Jones, Jean Galloway, Pip Payne, Tess Humphreys, William Macleod, Ravjit Khangura, M. Aberra, H. Mian, Geoff Thomas, Dusty Severtson, Peter Mangano, Monica Kehoe, Madeline A. Tucker, Neil Barker, Robert Loughman, Larisa Cato, Ken Quail, Mohammad Amjad, Mark Seymour, Justin Kudnig, Mark Thompson, Anton Mannes, Michael Uttley, Chris Fletcher, Andrew Etherton, Nick Joyce, Kate Light, Peter Hamblin, Michael Lamond, Alan Meldrum, Wayne Parker, Steve Penny Jr, Sarah Ellis, Brenda Shackley, Christine Zaicou, Shajahan Miyan, Darshan Sharma, Ben Curtis, Greg Shea, Bevan Buirchell, David Harris, Bob French

Crop Updates

This session covers twenty four papers from different authors:

PLENARY

1. Challenges facing western Canadian cropping over the next 10 years, Hugh J Beckie, Research Centre, Agriculture and Agri-Food Canada, Saskatoon,

Saskatchewan

CROP SPECIFIC

Breeding

2. The challenge of breeding canola hybrids – new opportunities for WA growers, Wallace Cowling, Research Director, Canola Breeders Western Australia Pty Ltd

3. Chickpea 2009 crop variety testing of germplasm developed by DAFWA/CLIMA/ICRISAT/COGGO alliance. Khan, TN1,3, Adhikari, K1,3, Siddique, K2, Garlinge, J1, Smith, L1, Morgan, S1 and Boyd, C1 1Department …