Rita Gollihur

8/14/2019 Rita Gollihur

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Scientic Report 2007

3D Glasses InsideA leaf infected with

cucumber necrosis virus.

A cutaway of the

cucumber necrosis virus.


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Cover FiguresScientists at the Danorth Center are interested in how plants ghtdisease. Dr. Tom Smith is studying the structure and unction o severalanimal and plant viruses such as cucumber mosaic virus, cucumbernecrosis virus, and murine norovirus.

The stereo image on the right shows a cutaway view o the structure ocucumber necrosis virus (CNV). This image was produced using sampleso the virus rozen in liquid nitrogen and computer programs combinedthousands o images to reconstruct the three-dimensional structure o theintact virus. There are three layers in this virus; the outer protein shell,ollowed by a shell o the viral RNA genome, and then an internal proteincore. For clarity, the RNA layer has been removed to show the innerprotein core in the virus.

On the bottom let is an example o a cucumber lea inected with CNV.Image provided by Dr. DAnn Rochon, Research Scientist, Pacic Agri-Food Research Centre, British Columbia.

The Donald Danorth Plant Science Center is anot-or-proft research institute with a global vision to

improve the human condition. Research at theDanorth Center will enhance the nutritional content

o plants to improve human health, increaseagricultural production to create a sustainableood supply, and provide the scientifc ideasand technologies that will contribute to the

economic growth o the St. Louis regionand o the State o Missouri.


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Table of Contents

2007 Scientifc Report The Donald Danorth Plant Science Center

Chairmans Letter.........................................................................................................................................................2

Board o Trustees ..........................................................................................................................................................2

Presidents Letter ..........................................................................................................................................................3

Science Advisory Board ..............................................................................................................................................3

Introduction To Principal Investigators ....................................................................................................................4

Principal Investigators

W. Brad Barbazuk .......................................................................................................................................................... 7

Roger Beachy .................................................................................................................................................8

Domain Member: Tahzeeba Hossain ..........................................................................................26

Domain Member: Shunhong Dai ................................................................................................26

Edgar Cahoon ................................................................................................................................................9

Claude Fauquet ...........................................................................................................................................10

Eliot Herman ................................................................................................................................................11

Jan Jaworski ..................................................................................................................................................12

Joseph Jez ......................................................................................................................................................13

Toni Kutchan ................................................................................................................................................14

Mark Running ..............................................................................................................................................15

Daniel Schachtman ......................................................................................................................................16

Domain Member: Ryoung Shin ...................................................................................................26

Dilip M. Shah ...............................................................................................................................................17

Thomas Smith ..............................................................................................................................................18

Christopher Taylor ......................................................................................................................................19

Nigel Taylor .................................................................................................................................................................. 20

Xuemin (Sam) Wang ...................................................................................................................................21

Terry Woodord-Thomas ............................................................................................................................22

Yiji Xia ..........................................................................................................................................................23

Liming Xiong ...............................................................................................................................................24

Oliver Yu .......................................................................................................................................................25

Scientic Shared Facility Managers

R. Howard Berg ............................................................................................................................................................ 27

Edward Fischer ............................................................................................................................................................28

Leslie Hicks ................................................................................................................................................................... 29

Kevin Lutke ..................................................................................................................................................................30

International Programs

Sharon Berberich .......................................................................................................................................................... 31

Society O Fellows ........................................................................................................................................................................32

Undergraduate Research Intern Program ..............................................................................................................33

Seminar Speaker Series .............................................................................................................................................34


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Donald Danforth Plant Science Center

Board of Trustees

William H. Danorth, M.D., ChairmanChancellor EmeritusWashington University in St. Louis

Bruce Alberts, Ph.D.ProessorUniversity o Caliornia-San Francisco

Daniel A. BurkhardtManaging DirectorOakwood Medical Management, LLC

France A. Crdova, Ph.D.PresidentPurdue University

Brady J. Deaton, Ph.D.ChancellorUniversity o Missouri-Columbia

Hugh GrantChairman, President & Chie ExecutiveOfcer

Monsanto Company

Richard Herman, Ph.D.ChancellorUniversity o Illinois at Urbana-Champaign

David W. KemperChairman, President & Chie ExecutiveOfcerCommerce Bancshares Inc.

Alex F. McCalla, Ph.D.Proessor EmeritusDepartment o Agricultural &Resource EconomicsUniversity o Caliornia, Davis

John F. McDonnellRetired Chairman o the BoardMcDonnell Douglas Corporation

Philip Needleman, Ph.D.Former Chie ScientistPharmacia and Monsanto Company/Searle

Peter H. Raven, Ph.D.DirectorMissouri Botanical Garden

Alonso Romo GarzaChairman & CEOPulsar International, Mexico

P. Roy Vagelos, M.D.Retired Chairman & CEOMerck & Company

Robert L. Virgil, D.B.A.Management Development ConsultantEdward Jones

Mark S. Wrighton, Ph.D.ChancellorWashington University in St. Louis

Usha Barwale Zehr, Ph.D.Joint Director o ResearchMaharashtra Hybrid Seeds Company

The Donald Danorth Plant Science Center 2006 Scientifc Report2

The Board o the Donald Danorth Plant Science Center is proud to beassociated with the scientists whose work is documented in this Report.

We believe that advances in science, that is advances in humanunderstanding o nature, are closely linked to advances in human wellbeing. Today, compared with the generations that went beore, we live in anearthly paradise. We in St. Louis can go to a Schnucks market and purchaseappetizing ood rom all over the world, resh, rozen, in boxes, and cans andcartons. More importantly it is nutritious, sae and very cheap.Without science we would not be living so well. Without science, Asia, LatinAmerica and the Middle East would still be wracked by periodic amines.

Now we look to science and scientists to improve our understandingo plants so that new innovations will lead to the end o starvation andimproved nutrition world wide while at the same time preserving andrenewing the environment.

We are optimistic that our Center will play an important role in this greathuman challenge.

William H. Danorth, M.D.Chairman o the Board o Trustees


5/382006 Scientifc Report The Donald Danorth Plant Science Center

Donald Danforth Plant Science Center

Science Advisory Board

Luis Herrera Estrella, Ph.D.DirectorCinvestav-IPN, Mexico

John Johnson, Ph.D.Proessor

Department o Molecular BiologyThe Scripps Research Institute

Jonathan Jones, Ph.D.Group LeaderThe Sainsbury LaboratoryJohn Innes Centre

Norman G. Lewis, Ph.D.DirectorInstitute o Biological ChemistryWashington State University

Ronald L. Phillips, Ph.D.Regents ProessorMcKnight Presidential Chair in Genomics,DirectorCenter or Microbial and Plant GenomicsUniversity o Minnesota

Philip Needleman, Ph.D.Board o TrusteesDonald Danorth Plant Science Center

Marc C.E. Van Montagu, Ph.D.ProessorLaboratory o GeneticsUniversity o Ghent, Belgium

During the past year we witnessed a signicant increase in public awareness

about the environment and the role that human activities play on the future of

the earth. Concerns about global issues, including in global climate change and

the role of anthropogenic inuences on survival of species of animals, plants,

and microbes were voiced with increasing frequency and urgency from many

different quarters. Reports issued from the United Nations Commission on

Global Climate Change provided a consensus of opinion of scientists that human

activities likely have an impact on climate change; for example, emissions

of greenhouse gases such as carbon dioxide (CO2) and methane (CH

4), can

signicantly increase the greenhouse effect. These studies suggest that, given

that the increase in greenhouse gases over the past 50 yrs are only now having a

measured effect on climate, it is urgent to begin to reduce the emissions of such

gases immediately so as to reduce their impacts over the next 50 100 years.

Plants and algae are natural collectors and concentrators of CO2; they also

produce CO2

when they decompose, are burned directly, or used as biofuels

such as ethanol or biodiesel. Nevertheless, using plants as a source of fuels and

other industrial materials (bers, polymers, feedstocks for the chemical industry

will reduce our reliance on ancient black carbon (petroleum and coal), and

create a future based increasingly on green carbon. The Danforth Centers

mission to Improve the Human Condition through Plant Science helps to

focus our research on topics that enhance and renews our environment so as to

preserve the world for our children and grandchildren. During 2007, research

at the Center involved studies that may increase the quality and quantity of

biodiesel from soybeans and other oil seed crops, and other topics that address

environmental issues. In 2008 activities in this topic area will increase as theEnterprise Rent-A-Car Institute for Renewable Fuels is staffed and builds; and,

as new research on producing new biomaterials in plants sponsored by the

Missouri Life Sciences Fund gets underway.

While work at the Danforth Center will reduce reliance of all of us on black

carbon in favor of green carbon, we realize that long term solutions will come

from many sources: for example, from conservation of all types of energy. Of

course, our research will not be conducted in isolation, but will be part of a

community of research conducted in many different disciplines, including in the

hard sciences as well as in social sciences, economics and in policy making.

Our work to Improve the human condition through plant sciences has just

begun and will continue through our 10th year (in 2008), and for years to come

Roger N. Beachy, Ph.D.President


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Roger Beachy Ph.D., Botany and Plant Pathology, Michigan State University

Dr. Beachys research builds on breakthrough discoveries made in the 1980s thatresulted in the rst transgenic crop, a virus-resistant tomato. Dr. Beachy and hiscolleagues investigate how viruses enter plant cells, are replicated, and spreadthroughout the host, and indentiy host genes that respond to inection. Thesestudies will lead to new methods to control virus disease in plants.

The seeds o plants contain hundreds o dierent types o oils, and many o these seedoils have potential industrial and nutritional value. Through his studies o the geneticand biochemical diversity o plants, Dr. Cahoon has identied genes associated withproduction o unusual seed oils and is studying the cellular processes involved in oilproduction. He is using this knowledge to produce useul vegetable oils in soybean.

Edgar Cahoon Ph.D., Botany and Plant Pathology, Michigan State University

Dr. Fauquet directs the International Laboratory or Tropical Agricultural Biotechnology(ILTAB). ILTAB has a threeold mission: to improve tropical crops through theapplication o molecular biology and biotechnology, to aid developing countries bytraining scientists and transerring useul biotechnologies, and to help coordinatebiotechnology research on tropical crops worldwide.

Claude Fauquet Ph.D., Biochemistry, University of Strasbourg

Dr. Herman investigates the cell biology o seeds, specically looking at the processesin plant cells that allow seeds to accumulate the proteins they will need or germination.His main ocus is soybean, a plant whose seeds are an important source o humannutrition especially o high quality protein. Dr. Hermans work aims to modiy seedproteins to eliminate allergenic properties and increase nutritional value.

Eliot Herman* Ph.D., Biology, University of California, San Diego

Recently, there has been interest in improving the nutritional and economic value oseed oils in such plants as soybean, corn, and canola. Dr. Jaworski studies componentso the metabolic pathways that plants use to synthesize oils. This work will acilitate

modication o seed oil composition and quantity and lead to new uses or theseoils.

Jan Jaworski Ph.D., Biochemistry, Purdue University



* U.S. Department o Agriculture, Agricultural Research Service

W. Brad Barbazuk Ph.D., Genetics, Simon Fraser University

Dr. Barbazuks research is ocused on understanding genome architecture, unctionand evolution. Dr. Barbazuk is conducting computational biology research projectsinvolving plant (Zea mays ) and microbial genomes (Xenorhabdus ) that will provide

some o the initial data required to address questions o genome organization, geneinteraction and regulation.

Dr. Jez is interested in the molecular basis o natural product and hormone synthesis inplants. His laboratory combines techniques rom biochemistry, protein engineering,and x-ray crystallography to investigate the structure o molecules controlling thesebiosynthetic processes. This research promises wide-ranging benets or improvingcrops, such as developing plant-based heavy-metal detoxication o soils.

Joe Jez Ph.D., Biochemistry and Molecular Biophysics, University of Pennsylvania




Mark Running Ph.D., Genetics, California Institute of Technology

The various parts o a plant develop rom meristems, small groups o actively dividingcells. Meristems allow plants to adapt their orms to the environment. Dr. Runningstudies the genetic characteristics o mutations that change the unction o meristems.Such mutations reveal inormation about how plants germinate, send up shoots,produce fowers, and extend their roots.

Thomas Smith Ph.D., Biochemistry, University of Rochester

One key to discovering how plants unction and how pathogens inect them isthrough the study o molecular structure. Dr. Smith investigates the structure ovirus particles and o enzymes using high-resolution microscopy, x-ray analysis ocrystal structures, and studies o molecular interactions. His research will providenew ways to control viruses and to modiy enzymes that are involved in essentialplant processes.

Dr. Kutchan and colleagues are investigating how medicinal plants synthesize andstore special types o chemicals called natural products. Plant natural products areoten physiologically active and serve as pharmaceuticals in both traditional andmodern medicine. An understanding o the enzymes and genes involved in naturalproduct biosynthesis will acilitate the application o biotechnology to improvemedicinal plants or the production o pharmaceuticals.

Toni Kutchan Ph.D., Biochemistry, Saint Louis University(Starting March 2006)

Dilip Shah Ph.D., Genetics, North Carolina State University

Eective and sustainable control o ungal pathogens remains one o the mostimportant challenges o modern agriculture. The innate immune system o plantsprovides the rst line o constitutive or inducible deense against inectious ungaldiseases. Dr. Shah and his team are studying small cysteine-rich antiungal proteinscalled deensins which are the ubiquitous plant proteins implicated in the rst-linehost deense against ungal pathogens.

Daniel Schachtman Ph.D., Genetics and Plant Physiology, Australian National University

Dr. Schachtman specializes in the study o roots, which plants use to take in needed

water and minerals. He investigates the mechanisms roots use to obtain minerals,ocusing specically on reducing salt intake and increasing zinc uptake. Such studieswill lead to improvements that increase tolerance to poor soils, enhance growth, andadd nutritional value.

Christopher Taylor Ph.D., Genetics, North Carolina State University

The roots o plants not only take in water and minerals, they also release chemicalsubstances to the soil. Dr. Taylor analyzes the way plants synthesize these chemicals.He also studies the roles o these chemicals in deterring pathogens, maintaining

symbiotic relationships between the plant and benecial soil organisms, and causingthe soil to release nutrients or use by the plant.

Nigel Taylor Ph.D., Plant Tissue Culture, University of Bath, UK

Dr. Taylor employs tissue culture and genetic transormation technologies to enhancecassava,Manihot esculenta, or disease resistance and increased nutrition as a membero the International Laboratory or Tropical Agricultural Biotechnology (ILTAB). Thegoal o his research is to generate improved agricultural products or resource-poorarmers in the tropics, and to train scientists rom these regions to produce and testenhanced crops.


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Yiji Xia Ph.D., Genetics, Iowa State University

When a plant is attacked by a pathogen, a signal is sent rom the site o inection tothe rest o the plant. This generates physiological changes that help the plant deenditsel. Dr. Xia is working to characterize this signaling mechanism. Such knowledgecan be used to develop crops with durable and environmentally riendly diseaseresistance.

Liming Xiong Ph.D., Plant Biology, University of Arizona

Dr. Xiong investigates the cellular machinery that allows plants to adapt toenvironmental stress such as drought or poor soils. His laboratory studies thebioregulation o the plant hormone abscisic acid, which controls many cellularprocesses including stress response. Knowledge gained rom this research will allowscientists to devise strategies or increasing stress tolerance in crop plants.


Xuemin (Sam) Wang* Ph.D., Plant Physiology and Biochemistry, University of Kentucky

Lipids are important cellular constituents in living systems and provide the structuralbasis or cell membranes and uel or metabolism. They also unction as messengersmediating growth and development. Dr. Wangs research goal is to improve plant

output and product quality by studying the signaling and metabolic unctions omembrane lipids in plant growth and response to environmental changes.


* E. Desmond Lee and Family Endowed Proessor, University o Missouri-St. Louis

Terry Woodford-Thomas Ph.D., Developmental Biology, Virginia Polytechnic Institute and State University

Dr. Woodord-Thomas and her team are ocused on developing the technology to useagricultural plants or the production and delivery o oral vaccines that are designedto induce protective immunity against inectious disease pathogens o humans andanimals.

Oliver Yu Ph.D., Genetics and Plant Physiology, University of South Carolina

Isofavones are compounds that plants create to signal helpul bacteria in the soil,but they are also thought to provide signicant health benets to people. Dr. Yuinvestigates the metabolic pathway that plants use to produce isofavones. With thisknowledge, he can study plant-signaling mechanisms and alter isofavone productionto enhance human health.


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W. Brad Barbazuk, Ph.D.Assistant Member

My research addresses questions concerning genome architecture, unction andevolution.

Recent Publications:Latreille P, Norton S, Goldman BS, Henkhaus J, Miller N, Barbazuk B, Bode HB, Darby C, Du Z, Forst S, Gaudriault S, Goodner B,

Goodrich-Blair H, Slater S. 2007. Optical mapping as a routine tool or bacterial genome sequence nishing. BMC Genomics.14;8:321.

Diana Dembinsky, Katrin Woll, Muhammad Saleem, Yan Liu, Yan Fu, Lisa A. Borsuk, Tobias Lamkemeyer, Claudia Flatterer, JohannesMadlung, Brad Barbazuk, Alred Nordheim, Dan Nettleton, Patrick S. Schnable, Frank Hochholdinger. 2007 Aug 31. Transcriptomicand proteomic analysis o pericycle cells o the maize primary root. Plant Physiology. 145:575-88. Epub.

Makarevitch I, Stupar RM, Iniguez AL, Haun WJ, Barbazuk WB, Kaeppler SM, Springer NM. 2007 Jul 29. Natural Variation or AllelesUnder Epigenetic Control by the Maize Chromomethylase Zmet2. Genetics. 177:749-60. Epub.

W. Brad Barbazuk*, Scott J. Emrich*, Hsin D. Chen, Li Li, and Patrick S. Schnable. 2007 Jul 27. SNP discovery in maize via 454transcriptome sequencing. Plant J. *authors contributed equally

Scott J. Emrich*, W. Brad Barbazuk*, Li Li and Patrick S. Schnable. 2006 Nov 9. Gene discovery and annotation using LCM-454transcriptome sequencing. Genome Research. Jan;17(1):69-73. Epub. *authors contributed equally

Lab Members:Yan Fu Ph.D., Postdoctoral AssociateHao Peng Ph.D., Postdoctoral AssociateChenhong Zhang MSc, Postdoctoral Associate

[email protected]


My interests lie in attempting to understand plant genomearchitecture, unction and evolution. Most o my current ocusis on cereal genomes, where I apply comparative analysis andcomputational methods to investigate gene structure, genecontent, gene/genome organization and regulation with the goalo applying this knowledge to aect cereal crop improvement;I am interested in establishing high resolution comparativemaps between rice, maize and other cereals; investigatinggene organization in completed plant genomes; investigatinggene annotation and alternative splicing; and, identiying andcharacterizing rapidly evolving genes.

Gene Annotation and gene structureI am currently analyzing maize gene structure in collaborationwith Dr. Michael Brent at Washington University. Throughunding provided by the National Science Foundation (maize)and USDA (tomato) we are studying gene structure and usingthis inormation to improve Ab initio gene prediction in thesecrops.

Alternative splicing in PlantsWhile alternative splicing is extensive in humans and otherhigher animal genomes, it is less common in plants. I aminterested in examining the requency o splicing in maize aswell as the requency o dierent types o splicing (skippedexon, alternative 5, alternative 3 etc.). This may address theevolution o splicing mechanisms in plants; and, identiysequence signals associated with alternatively spliced exonsthat could be used to improve alternatively spliced geneprediction. It has been suggested that alternative splicingcreates transcriptome diversication, which may account ordiversity among organisms with relatively similar gene sets(i.e. Mammals). Identiying alternatively spliced genes in maizewill allow us to address whether or not spliced genes (and the

variants) are conserved among plant species, and i not, this mayidentiy genes involved in speciation. We are currently miningthe available maize sequence data or evidence o alternativesplicing, and examining the use o 454 transcriptome sequencingor identication o rare (tissue-specic) splice isoorms.

Applications o Next-Generation sequencing to PlantGenomicsNext generation sequencing technologies such as 454 DNAsequencing and Solexa sequencing technology achievessignicant throughput relative to traditional approaches. Mylab develops strategies to use these technologies to examineplant genomes. Specically, we have generated and annotated>500K 454 ESTs rom maize shoot apical meristem, anddemonstrated the value o this technology to identiy novel andtissue specic transcripts. In addition, we have developed highthroughput computational methods or SNP discovery rom 454sequence. Current projects include small RNA discovery, novetranscript and expression analysis in tomato, gene expressionand polymorphism detection in maize using Solexa sequenceand DNA binding site studies (Chip-Seq).

This gure depicts the extent of genome synteny betweenthe maize and rice genome.

Rice Chromosome Colors


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Roger Beachy, Ph.D.Member

Research in my laboratory targets interering with interactions between plantviruses and their hosts, and developing strategies to control gene expression in

plants.

Lab Members:Maria Soto-Aguilar, Ph.D., Postdoctoral AssociateShunhong Dai, Ph.D., Domain Assistant MemberBrian Kelly, Laboratory Technician IIYi Liu, Ph.D., Postdoctoral FellowIsabel Ordiz, Ph.D., Research ScientistLiping Pei, Laboratory TechnicianJaemo Yang, Ph.D., Postdoctoral AssociateXioaping Wei, Research Associate I

Executive Assistant:Allison BrownAdministrative Assistant:Kathleen Mackey

Recent Publications:

Liu, Y., S. Dai, R.N. Beachy. 2007. Role of the C-terminal domains of rice bZIP proteins RF2a and RF2b in regulating transcription. Biochem J.

405: 243-249.

Bazzini, A., HE. Hopp, R.N. Beachy and Sebastian Asuremendi. 2007. Infection and co-accumulation of Tobacco Mosaic Virus proteins alter

microRNA accmumulation, correlating with symptom on plant development. Proc. Natl. Acad. Sci. U.S.A. 104 (29) 12157-12162.

Asurmendi, S., R.H. Berg, T.J. Smith, M. Bendahmane, and R.N. Beachy. 2007. Aggregation of TMV CP plays a role in CP functions and in coat-

protein mediated resistance. Virology. 366: 98-106.

Bendahmane, M., I.Chen, S. Asurmendi, A. Bazzini, J. Szecsi, and R.N. Beachy. 2007. Coat protein-mediated resistance to TMV infection of

Nicotiana tabacum involves multiple modes of interference by coat protein. Virology. 366: 107-116.

[email protected]


Virus replication is regulated by both host-encoded and virus-encoded genes. Similarly, host cells and tissues respond toinection by viruses and either permit or restrict replicationand local and long distance spread o inection. The Beachylab is engaged in studies to determine how inection sites areestablished and developing strategies to control inection andto restrict replication and spread in simple RNA-containingviruses and a more complex pararetrovirus. Knowledge romstudies o the pararetrovirus are used to develop a chemicallycontrolled gene switching system to regulate expression otransgenes in plants.

Molecular virology and biotechnology: Our studies o tobaccomosaic tobamoviruses target greater understanding o howviral and host proteins regulate virus replication and cell-cellspread o inection. Viral coat proteins (CP) o tobamovirusesregulate expression o the movement protein (MP), therebyimpacting the ormation o virus replication complexes andcell-cell spread. We proposed that cell-cell spread results rommovement o VRCs through plasmodesmata. We are currentlycharacterizing the proteome(s) o VRCs that are assembled inthe presence and absence o MP, and urther characterizing therole o MP in targeting VRCs to plasmodesmata. We are alsocollaborating with Dr. Howard Berg (Integrated MicroscopyFacility) to establish ultrastructural characteristics o the VRCs.

Recently we initiated a collaborative project with theInternational Potato Center (CIP; Lima, Peru) and NationalAgricultural Research Organization (Namulonge, Uganda) todevelop strategies to control sweet potato virus disease. Wealso developed transgenic lines o rice that contain cis-genes

and trans-genes that coner resistance to rice tungro disease(below) that will be evaluated or eld resistance in Asia.

Gene regulation and biotechnology: Studies o Rice TungroBacilliorm badnavirus (RTBV) led to identication otranscription actors that regulate virus replication. The relevanttranscription actors, RF2a and RF2b, and RLP1 also unctionin development o vascular tissues o rice. The role o theseactors, and genes that are controlled by these actors, in plantdevelopment are under study.

The transcription actors RFa, RF2b, and RLP1 are beingdeveloped to used a plant gene switching system based on theEcR receptor and a chemical ligand, methoxyenozide. Our goalis to urther improve the gene switching system, and to apply

the system to modiy pathways that lead to accumulation ospecic products o primary and secondary metabolism. Genesthat are being targeted or regulation include those that regulate

wax biosynthesis and genes that control biomass productionThese studies enable the exploration o complex pathwaysin transgenic plants while minimizing the eects o over andunder expression o genes on plant transormationper se.

The structures projected inward from the cell surface in this plant cell/

protoplast are components of the ER, but its structure is highly distorted

due to the infection by TMV, which causes distortion of the ER as virus

replication complexes are established. The protoplast was infected

with TMV that produces the 30kDa movement proteins fused with

GFP. Some of the enlarged areas of the ER represent virus replication

complexes (VRC). Please use 3D (red/cyan) glasses provided.

Imaging by Dr. Howard Berg. 3D reconstruction (surface rendering) from

confocal optical sections of a tobacco BY-2 protoplast (30m diameter).


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Fatty Acid Modifcation o VegetableOils: Vegetable oils produced by cropssuch as soybean oer a platorm or thesustainable production o atty acidsor human and livestock nutrition, bio-

based uels, and industrial chemicals.We are currently studying ways toproduce vegetable oils that are enrichedin conjugated atty acids, which can

be used in livestock eed to reduce ataccumulation and as drying agents inpaints and inks. Our work is unded bya collaborative NSF grant that involvesthe use o genomics to identiy enzymes

that are specialized or the metabolismo conjugated atty acids in the seeds othe non-agronomic plantMomordica charantia. Genes obtainedrom this plant will be used to engineer the sustainableproduction o conjugated atty acids in established oilseed crops.We are also conducting research as part o international eort toproduce wax esters in oilseed crops. These atty acid derivedcompounds have value as high temperature lubricants thatoer a renewable substitute or petroleum-based lubricants.

Vitamin E Antioxidant Enhancement o Soybean Oil: Thevitamin E antioxidants tocopherols and tocotrienols coneroxidative stability to vegetable oils, which is important or theiruse as rying oils in ood processing and as bio-based lubricants.

We have succeeded in engineering soybean seeds to producegreater than six-old higher levels o vitamin E antioxidants,primarily in the orm o tocotrienols. Field plantings wereconducted with these soybean lines during the summer o 2007.Seeds rom these plants will be examined or improved storagelie, and extracted vegetable oils will be evaluated or possibleenhancement o oxidative stability.

Cassava Bioortifcation: In an ongoing collaboration with

Dr. Claude Fauquet and Dr. Nigel Taylorwe are attempting to metabolicallyengineer cassava storage roots toproduce nutritionally signicant levelso provitamin A and vitamin E. Byincreasing the expression o key enzymesin the plastid isoprenoid pathway, weare attempting to generate higher levelso the provitamin A -carotene and thevitamin E -tocopherol. During the pasyear, we have obtained storage rootsrom greenhouse-grown cassava plantswith signicant increases in -carotenecontent. Field trials are planned or these

genetically-enhanced lines.

Sphingolipid Biosynthesis and Function: Sphingolipids aremajor components o the plasma membrane and tonoplasts oplant cells and likely play important roles in the plants responseto biotic and abiotic stresses. We are attempting to understandthe synthesis and unction o sphingolipids in Arabidopsis inorder to produce higher yielding crops with improved stresstolerance. Research conducted during the past year has shownthat genetic blocking o a key step in sphingolipid structuramodication leads to a two- to three-old increase in the totacontent o sphingolipids inArabidopsis.

Edgar Cahoon, Ph.D.Associate Member

My research is aimed at enhancing the nutritional and industrial value of crop plants. My

research also examines the synthesis of bioactive lipids for nutritional biofortication and

improved agronomic performance of crops.

Lab Members:Shaneena S. Adams, Laboratory TechnicianRebecca E. Cahoon, Research AssociateMing Chen, Research ScientistCharles R. Dietrich, Post-doctoral AssociateSarah C. Hunter, Post-doctoral AssociateElliott T. Klotz, Laboratory Technician

Jamie M. Shipp, Laboratory TechnicianMatthew J. Shipp, Laboratory TechnicianFelix R. Solomon, Research AssociateRobyn L. Stevens, Research AssociateWenyu Yang, Post-doctoral AssociateChunyu Zhang, Post-doctoral Associate

Recent Publications:Cahoon EB, Schmid KM. 2007. Metabolic engineering o the content and atty acid composition o vegetable oils. In Bioengineering and

Molecular Biology o Plant Pathways.Advances in Plant Biochemistry and Molecular Biology, Vol. 1. Bohnert H, Nguyen H, Lewis N(eds). Elsevier, Burlington, MA, pp. 159-198.

Cahoon EB, Hitz WD, Ripp KG. 2007. Method or the production o calendic acid, a atty acid containing delta-8,10,12 conjugateddouble bonds and related atty acids having a modication at the delta-9 position. United States Patent # 7,230,090.Cahoon EB, Carlson TJ, Hitz WD, Ripp KG. 2007. Genes or plant atty acid modiying enzymes associated with conjugated double

bond ormation. United States Patent # 7,244,563.Cahoon EB, Shockey JM, Dietrich CR, Gidda SK, Mullen RT, Dyer JM. 2007. Engineering oilseeds or sustainable production o

industrial and nutritional eedstocks: solving bottlenecks in atty acid fux. Current Opinion in Plant Biology 10:236-244.Dietrich CR, Han G, Chen M, Berg RH, Dunn TM, Cahoon EB.2008. Loss-o-unction mutations and inducible RNAi suppression o

ArabidopsisLCB2 genes reveal the critical role o sphingolipids in gametophytic and sporophytic cell viability. Plant JournalHunter SC, Cahoon EB. 2007. Enhancing vitamin E in oilseeds: unraveling tocopherol and tocotrienol biosynthesis. Lipids 42:97-108.Ramamoorthy V, CahoonEB, LiJ, Thokala M, Minto RE, Shah DM.2007. Glucosylceramide synthase is essential or alala deensin-

mediated growth inhibition but not or pathogenicity o Fusarium graminearum. Molecular Microbiology 66:771-786.Tsegaye Y, Richardson CG, Bravo JE, Mulcahy BJ, Lynch DV, Markham JE, Jaworski JG, Chen M, Cahoon EB, Dunn TM. 2007.

Arabidopsis mutants lacking long chain base phosphate lyase are umonisin sensitive and accumulate trihydroxy 18:1 long chainbase phosphate.Journal o Biological Chemistry 282:28195-28206.

[email protected]


Field planting of high vitamin E soybeans in summer of 2007.


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Claude Fauquet, Ph.D.Member

Our research is dedicated to tropical agriculture research and training.

Lab Members:Mohammed Abhary, Ph.D. StudentImran Amin, Visiting ScientistHellen Apio, Visiting ScientistBasavaraj Bagewadi, Ph.D., Postdoctoral AssociatePatil Basavaprabhu, Ph.D., Postdoctoral AssociateDeAnna Booker, Lab TechnicianYeetoh Chaweewan, Ph.D. StudentDavid Corbin, VIRCA Operations ManagerMindy Fitter, VIRCA Landrace Cassava Transformation ScientistMala Jayatilleke, Ph.D., Postdoctoral AssociateTira Jones, Lab TechnicianJacquelynn Kelly, Lab TechnicianMuhammad Shah Nawaz Khan, Postdoctoral AssociatePatsy Kohleld, Lab Technician

Ratna Kumria, Ph.D., Postdoctoral AssociateTheodore Moll, Lab TechnicianEmmanuel Ogwok, Visiting ScientistMarina Pestova, Ph.D., Research AssociateDanielle Posey, Lab TechnicianAriel Simmons, Lab TechnicianSareena Sahab, Postdoctoral Associate

Nigel Taylor, Ph.D., Assistant Domain MemberBrent Trauterman, Lab TechnicianJitender Yadav, Ph.D., Postdoctoral FellowXian Xie, Lab Technician


Shah Nawaz-ul-Rehman, Muhammad and Fauquet, C.M. 2007. Emerging Geminiviruses. In Mahy, Brian and Van Regenmortel, Marc, (Eds.Encyclopedia o Virology. Elsevier, London.

Abhary, Mohammad, Patil, Basavaprabhu L. and Fauquet, Claude M. 2007.Molecular biodiversity, taxonomy and nomenclature o Tomato yellow leacurl-like viruses in Czosnek, Henryk (Ed.) Tomato yellow lea curl virus disease. Springer, New York.Martelli, G, Fauquet, C.M. and Gallitelli, D. 2007. Emerging and reemerging virus diseases. In Mahy, Brian and Van Regenmortel, Marc, (Eds.

Encyclopedia o Virology. Elsevier, London.Fauquet, C. M. 2007. Viral classifcation and nomenclature. In Mahy, Brian and Van Regenmortel, Marc, (Eds.) Encyclopedia o Virology. Elsevier

London.Fargette, D, Konate, G, Fauquet, C, Muller, E, Peterschmitt, M, and Thresh, J. M. 2006. Molecular Ecology and Emergence o Tropical Plant

Viruses.Annu. Rev. Phytopathol. 44:235-260.Fauquet, C.M. 2006. The diversity o single stranded DNA viruses. Biodiversity (Ottawa), 7:38-44.Kouassi, N.K, Chen, L., Sir, C., Bangratz-Reyser, M., Beachy, R.N., Fauquet, C.M. and Brugidou, C. 2006. Expression o rice yellow mottle virus

coat protein enhances virus inection in transgenic plants.Archives o Virology, 151:2111-2122. DOI: 10.1007/s00705-006-0802-3.Marmey, P. and Fauquet, C.M. (2006). CMI/AAB Description o Plant Viruses Cassava vein mosaic virus.Ndunguru, J., Legg, J. P., Foana, I. B. F., Aveling, T. A. S., Thompson, G. and Fauquet, C. M. 2006. Identication o a deective molecule

derived rom DNA-A o the bipartite begomovirus o East Arican cassava mosaic virus. Plant Pathology, 55:210. Doi: 10.1111/j.13653059.2005.01289.x. Online publication date: 14-Oct-2005.

Raven, P., Fauquet, C.; Swaminathan, M. S., Borlaug, N., and Samper, C. 2006. Where next or genome sequencing? [Letter] Science (Washington DC). 311(5760):468.

[email protected]


The mission o the International Laboratory or TropicalAgricultural Biotechnology (ILTAB) is threeold: to advance theapplication o molecular biology and biotechnology or tropicalcrop improvement; to promote research capacity building indeveloping countries; and to help coordinate global biotechnologyresearch on cassava.

Understanding How Geminiviruses Inect Plants: Geminivirusesare very destructive viruses that can cause devastating diseasesin ood and ruit crops in all tropical regions o the world. Theirgenomes are composed o circular single stranded DNA and theyare subjected to gene silencing through an unknown mechanism.We ound that geminiviruses possess at least two gene silencingprotein suppressors (AC4 and AC2). Their complementary andcombinatorial action is responsible or the synergistic symptom

observed in cassava in Uganda in the 1990s that led to a pandemicdisease now spreading westward across Arica. We also discoveredthat the mode o action o the AC4 suppressor is unique in that it

binds to small miRNAs o the host, and may be responsible orthe dramatic disease symptoms. Recently we studied naturalreservoir plants rom Pakistan to understand what is the sourceo new viruses and satellites. We discovered a wealth o inectiousmolecules but we also ound that together they do not causea disease; we are now attempting to determine the molecularmechanisms behind this phenomenon.

Enhancing Virus Resistance in Cassava: Geminiviruses causethe cassava mosaic disease (CMD), the most devastating cassavadisease in Arica, resulting in annual crop losses o 30 percent ormore. ILTAB, with support rom USAID, the Monsanto Fund andthe Bill & Melinda Gates Foundation and in collaboration with EastArican partners, has set up a team o scientists and techniciansto produce cassava plants that are resistant to the disease. Twostrategies are being developed: a ssDNA binding protein-basedstrategy (called G5); and a gene silencing-based strategy, withthe goal to use both in the same plants to increase widespreadprotection and resistance. The rst transgenic plants that showedstable virus resistance in the greenhouse will be tested in Ugandaand Kenya in 2008.

Enhancing the Nutritional Content o Cassava: Cassava rootsare very rich in starch and are a major source o calories orapproximately 700 million people worldwide. Unortunatelythese roots are decient in protein, vitamins and micronutrientsThe Danorth Center is part o an international team o cassavaresearchers that has been awarded a ve-year grant rom the Bill& Melinda Gates Foundation, aimed at enhancing the nutritionaqualities o cassava. ILTAB is specically involved in introducinggenes that will enhance levels o proteins and vitamins A, E(in collaboration with Dr. Edgar Cahoon). A complete proteinlandscape description o the cassava root proteome has beendone or the rst time and will serve as a reerence or proteinexpression and storage in cassava roots. The rst transgenic plantsaccumulating very high levels o proteins and vitamins have beenproduced and are under evaluation now in the greenhouse and

soon in the elds in Puerto Rico.


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Eliot Herman, Ph.D.U.S. Department o Agriculture, Agricultural Research ServiceMember

My research is ocused on modiying soybean proteins to improve composition,produce novel products, and reduce allergenicity.

Lab Members:Julie Francois, Postdoctoral AssociateChristina Rogenski, TechnicianMonica Schmidt, Assistant Domain Member

Recent Publications:Livingstone, D., Beilinson, V., Kalayaeva, M. Schmidt, M.A, Herman, E. M. and Nielsen, N.C. 2007. Reduction o protease inhibitor

acitivity by expression o a mutant Bowman-Birk gene in soybean seed. Plant Molec. Biol. 64, 397-408.DP Livingston III, K Van, R Premakumar, SP.Tallury, and EM Herman. 2006. An assessment o the use oArabidopsis thaliana as a model

to study reezing tolerance in small grains. Cryobiology. 54, 154-163Barrows, FT., D. Bellis, A. Krogdahl, J.T. Silverstein, E.M. Herman, W.M, Sealey, M. B. Rust, D., M Gatlin III. 2007. Report o the plant

products in aquaeed strategic planning workshop: An integrated , interdisciplinary research roadmap or increasing utilization oplant eedstus in diets or carnivorous sh. Aquaculture Research. 38, 551-579.

Herman, Eliot. 2007. Mitigation o soybean allergy by development o low allergen content soybeans. Ed. D.D.P. Siantar, M.W. Truckness, P.M. Scott, E.M. Herman. 2006. American Chemical Society, Mycotoxins qnd ood allergens; papers rom

symposium rom the 2006 American Chemical Society Annual Meeting.

[email protected]


The primary focus of my research programis producing modications of soybeanseed proteins to improve composition, toproduce novel and high value products, andto reduce intrinsic allergenicity. The goal isto ultimately increase soybean utilization as

both animal feed and human food as wellas provide new opportunities to producevalue-added industrial products in soybean.A new project is to create biotech peanutswith similar objectives to the allergenicitysoybean projects.

Soybean allergens have become an important

issue with the implementation of the federalFood and Allergen Labeling Act in 2006 thatnamed soybean as one of the eight allergenswhose presence in food is regulated.In addition to humans, soybean allergy andfood intolerance is observed in neonatalswine, dogs, and in farmed salmon. Forexample, when soybean-based formula is fedto neonatal swine the result is an allergenicresponse aecting growth rates. Thislaboratory is a participant in an industry-supported project that is aimed to in parallelselect swine that are less soy-sensitive andin parallel develop soybeans that will elicit

less sensitivity. Likewise, aempts to usesoybean proteins as substitutes for shmeal,consisting of ocean captured forage sh,to farm-raised carnivorous sh, such assalmon, has shown that salmon exhibit anadverse response similar to that of a food allergy. Soybean allergiesin humans, swine, and sh are primarily manifested as atopic(skin) and intestinal eects although more serious reactions have

been documented. To improve soybean use by sensitive peopleand animals we are involved in producing soybeans with lowerintrinsic allergenicity that could permit soybeans to be consumedwithout its allergens. The protein that is the dominant soybeanallergen was discovered by my research in the 1990s and since

then this protein, called P34, has been thesubject of numerous studies and aemptsto minimize its content in soybean. Both

biotech and conventional P34 nulls arhave been produced. However, in additionto P34, there are several other soybeanproteins that are allergens.In collaborationwith soybean geneticist Professor TedHymowitz of the University of Illinois, theP34 null was crossed with other soybeanlines to create a stacked low allergen lineof conventional soybeans null for all threemajor allergens. This hypoallergenicsoybean is currently being expanded to

conduct performance tests, rst in sh andswine and later in humans. Performancetests on salmon involve proteomic analysisof the adverse eect of soybean on the mid-and distal intestine. These tests will yieldmarkers indicating the eects of soybeanon salmon that can be used to characterizeany improvement of soybean-inclusion feedperformance.

Soybean seeds are potential biofactories toproduce foreign proteins, such as industriaenzymes, at low cost with the economy ofscale of agriculture. The development o

soybeans as protein biofactories requiresengineering new approaches to producehigh levels of protein that are stablyaccumulated. We have developed newapproaches to increase foreign protein levels

in soybean to a level approaching economic viability. Low cost,mass production of enzymes is a critical component for manyindustries including food processing and cellulosic biofuels.

Intact chipped soybean seeds (A) and crushed

seeds (B) modeling soy our illuminated with

blue light to show the enhanced accumulation

of a reporter protein, green uorescent protein,

GFP. A and B; left, wildtype soybean seeds,

middle, transgenic soybean seeds having

~2% GFP, right, transgenic soybean seeds

with increased GFP accumulation to ~8% totalprotein. A uorescent microscope image of the

enhanced GFP expressing seeds showing GFP

accumulated in discrete sub-cellular organelles

called protein bodies is shown in (C).


14/38

Jan Jaworski, Ph.D.Member

My lab is conducting research to better understand the pathways and enzymes inplants that are involved in lipid biosynthesis.

Lab Members:Joel Clement, Ph.D., Postdoctoral Associate

Hongyu Gao, Ph. D., Postdoctoral Associate

Jixiang Han, Ph.D., Postdoctoral Associate

Aravind Jukanti, Ph. D., Postdoctoral Associate

Jia Li, Lab Technician

Jonathan Markham, Ph.D., Domain Assistant Member

Jeong-Won Nam, Ph. D., Postdoctoral Associate

Administrative Assistant:

Christine Ehret

[email protected]



Tsegaye, Y., Richardson, C. G., Bravo, J. E., Mulcahy, B. J., Lynch, D. V., Markham, J. E., Jaworski, J. G., Chen, M., Cahoon, E. B., andDunn, T. M. 2007.Arabidopsis mutants lacking long chain base phosphate lyase are umonisin sensitive and accumulate trihydroxy18:1 long chain base phosphate. J. Biol. Chem. 282: 28195-28206.

King, A., Nam, J.-W., Han, J., Hilliard, J. and Jaworski, J, G. 2007. Cuticular wax biosynthesis in petunia petals: cloning andcharacterization o an alcohol-acyltranserase that synthesizes wax-esters. Planta. 226:381-394

Markham, J. E. and Jaworski, J. G. 2007. Rapid measurement o sphingolipids romArabidopsis thaliana by reversed-phase high-perormance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. Rapid Commun MassSpectrom. 21:1304-1314.

Markham, J. E., Li, J., Cahoon, E. B. and Jaworski, J. G. 2006. Separation and Identication o Major Plant Sphingolipid Classes romLeaves. J. Biol. Chem. 281: 22684-22694

Plants accumulate oil in their seeds to provide both the energyand carbon necessary or a germinating seed to grow into a plant.While seeds rom crops are rich in edible vegetable oils, naturehas provided the plant kingdom with a broad assortment o oilcompositions, and some unusual oils may have useul industrialapplications. One ocus o the Jaworski lab is to identiy the genesresponsible or producing unusual oils that can be used to producea transgenic crop capable o synthesizing large quantities o theseoils. In addition, the Jaworski lab ocuses on obtaining a basicunderstanding o pathways involved in plant lipid synthesis. .

Modifcation o seed oil composition: A key aspect o thisresearch initiative is to obtain genes that will allow the productiono unusual atty acids in common crops such as soybean. Our

approach is to prepare cDNA libraries or random sequencing andthen carry out unctional analysis o clones potentially involvedwith atty acid modication and lipid synthesis. Our recent ocushas been a amily o genes rom petunia encoding cytochromeP450s and acyl tranerases that are involved in the synthesis oterminal or -hydroxy atty acids. We have identied the geneencoding a omega-hydroxylase that is responsible or producingvery high levels o omega-hydroxy atty acids on stigma o petuniafowers and we are using this gene to produce hydroxy atty acidsin seeds. The omega-hydroxylase was the subject o a patentling by the Danorth Center. In addition, we have identiedgenes encoding a wax synthase and glycerol-3-phosphate acyltranserases in petunia fowers and will use those in attempts to

alter the oil composition o seeds.

Sphingolipid metabolism and unction in plants: This research issupported by an NSF 2010 grant to scientists rom ve labs at ourlocations, including Ed Cahoon here at the Center. The goal o theproject is to characterize the biosynthetic pathway or sphingolipidsand study their unction in plants with altered sphingolipidcomposition. Using a new and powerul mass spectrometer at theDanorth Center, we have developed new analytical proceduresto rapidly characterize the complete sphingolipid composition o

Arabidopsis. This new tool provides us with the capability to easilyanalyze manyArabidopsis lines with mutations in the sphingolipidpathway. This is providing us with a much richer understandingo this poorly understood area o plant metabolism.


15/38

Joseph Jez, Ph.D.Assistant Member

Plants are amazing chemists capable o generating an arsenal o small molecules with anarray o biological activities. Our research ocuses on understanding the biosynthesio these compounds and how they exert their biological eects.

Lab Members:Kiani A.J. Arkus, Lab AssistantRebecca E. Cahoon, Research AssociateMegan A. Clements, NSF-REU Summer Intern

Julie A. Francois, Ph.D., USDA Postdoctoral AssociateSangaralingam Kumaran, Ph.D., Postdoctoral Associate

Soon Goo Lee, Graduate Student (Washington University)Mary L. Preuss, Ph.D., Postdoctoral AssociateRebecca S. Rivard, Lab AssistantAmy C. Schroeder, Lab AssistantLeia M. Wachsstock, STARS Summer Intern


Brendza KM, Haakenson W, Cahoon RE, Hicks LM, Palavalli LH, Chiapelli B, McLaird M, McCarter JP, Williams DJ, Hresko MC, Jez JM. 2007Phosphoethanolamine N-methyltranserase (PMT-1) catalyzes the rst reaction o a new pathway or phosphocholine biosynthesis inCaenorhabditis elegans. Biochem. J. 404, 439-448.

Fu CJ, Jez JM, Kerley MS, Allee GL, Krishnan HB. 2007. Identication, characterization, epitope mapping, and three-dimensional modeling o-subunit o -conglycinin o soybean, a potential allergen or young pigs. J. Agric. Food Chem. 55, 4014-4020

Herrera K, Cahoon RE, Kumaran S, Jez JM. 2007. Reaction mechanism o glutathione synthetase rom Arabidopsis thaliana: site-directedmutagenesis o active site residues.J. Biol. Chem. 282, 17157-17165.

Hicks LM, Cahoon RE, Bonner ER, Rivard RS, Sheeld J, Jez JM. 2007. In vitro and In vivo thiol-based regulation o redox-active glutamatecysteine ligase romArabidopsis thaliana. Plant Cell 19, 2653-2661.

Jez JM. 2007. Phosphatidylcholine biosynthesis as a potential target or inhibition o metabolism in parasitic nematodes. Curr. Enz. Inhib. 3133-142.

Jez JM, Schachtman DP, Berg RH, Taylor CG, Chen S, Hicks LM, Jaworski JG, Smith TJ, Nielsen E, Pikaard CS (2007) Developing a newinterdisciplinary lab course or undergraduate and graduate students: plant cells and proteins. Biochem. Mol. Biol. Educ. 35, 410-415

Kumaran S, Jez JM. 2007. Thermodynamics o the interaction between O-acetylserine sulhydrylase and the C-terminus o serine acetyltranseraseBiochemistry 46, 5586-5594.

Phartiyal P, Kim WS, Cahoon RE, Jez JM, Krishnan HB. 2007. The role o 5-adenylylsulate reductase in the sulur assimilation pathway osoybean: molecular cloning, gene expression, and kinetic characterization. Phytochemistry. 69, 356-364.

Shin R, Alvarez S, Burch AY, Jez JM, Schachtman DP. 2007. Phosphoproteomic identication o targets o theArabidopsis sucrose nonermentinglike kinase SnRK2.8 reveals a connection to metabolic processes. Proc. Natl. Acad. Sci. U.S.A. 104, 6460-6465.

[email protected]


Cysteine and Sulur Assimilation. Protein-protein interactionsplay an essential role in a range o cellular processes. Forexample, association o the two enzymes in cysteine biosynthesis(O-acetylserine sulhydrylase, and serine acetyltranserase)coordinates sulur assimilation and modulates cysteine synthesisin plants. Biophysical analysis o this interaction reveals how thismacromolecular complex is assembled, and provides new insightsinto the molecular mechanisms underlying the biochemicalregulation o cysteine synthesis in plants.

Redox Regulation o Plant Glutathione Biosynthesis. Glutathioneis a key regulator o intracellular environment and providesprotection against environmental stresses. Growing evidenceindicates that reactive oxygen species act as signaling molecules;

however, how changes in redox environment eects critical targetproteins is only beginning to be explored. Using a combinationo approaches, we showed that Arabidopsis glutamate-cysteineligase (GCL), the rate-limiting enzyme in glutathione biosynthesis,responds to changes in redox environment both in vitro and invivo through disulde bonds. The thiol-based regulation oGCL provides a post-translational mechanism or modulating itsactivity in response to cellular redox environment and suggestsa role or oxidative signaling in protecting plants rom a range oenvironmental stresses.

Towards Phytoremediation. To optimize plants as tools orenvironmental clean-up, it is essential to understand the molecular

basis o how plants protect themselves rom heavy metal toxicity.Phytochelatin peptides play a pivotal role in heavy metaldetoxication in plants. To improve their production in responseto heavy metal toxicity, we engineeredArabidopsis phytochelatin

synthase (PCS) to provide plants with improved tolerance tocadmium toxicity. Initial tests in transgenicArabidopsis plants werepromising. We are currently testing the eect o overexpressingthe mutant PCS in transgenic Brassica juncea (Indian mustard)which is a plant used or phytoremediation.

New Nematicide Targets. Parasitic nematodes o humansanimals, and plants are a major cause o disease worldwide andthe development o new nematicides requires the identicationo biochemical targets not ound in host organisms. Nematodessynthesize phosphatidylcholine, a major membrane lipid, bya route that diers rom mammals. This pathway convertsphosphoethanolamine to phosphocholine through the action ophosphoethanolamine methyltranserases (PEAMT). As part o a

collaborative eort with Divergence, Inc. (St. Louis, MO), we haveanalyzed two PEAMT rom the ree-living nematodeCaenorhabditielegans and the parasitic nematode Haemonchus contortus. I theessential role o the PEAMT is conserved in parasitic nematodes,then inhibition o these enzymes oers a new approach ortargeting parasites with compounds o medicinal, veterinary, oragronomic value.


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Mark Running, Ph.D.Assistant Member

Our lab studies how plant cells signal to each other, coordinating their actions ingrowth, division, maturation, and environmental responses.

Lab Members:Qin Zeng, Ph.D., Postdoctoral FellowXuejun Wang, Ph.D., Postdoctoral FellowSydney Pursel , Undergraduate Intern


Zeng, Q., Wang, X., and Running, M.P. 2007. Dual lipid modication oArabidopsis thaliana G-subunits is required or ecient plasmamembrane targeting. Plant Physiology. 143, 1119-1131.

Running, M. P. 2006. Genetics o Flower Development and Patterning. In: Floriculture, Ornamental and Plant Biotechnology Vol. I, 1-11.Teixeira da Silva, J. A., ed. Global Science Books, U.K.

[email protected]

Prenylated proteins are mislocalized in pluripetala mutants. The prenylated signal

transduction protein AGG2, shown here attached to the uorescent marker EYFP, is

tightly associated to the plasma membrane in wild type leaf cells (left), but is present in

cytoplasmic strands and the nucleus inplp leaf cells (right). Bar = 10 um.

My laboratory is interested in plant growth anddevelopmental mechanisms, and how these processes are

intertwined with the response of the plant to its environment,

particularly in drought conditions. The focus of our studies

is the function of plant meristems, which are equivalent to

stem cells in humans.

Meristems are small

groups of cells from

which all parts

of the plant arise.

By maintaining

a collection of

meristematic cells

throughout theirlives, plants are able

to adapt their form

to their environment.

The long-term goal

of understanding

meristem function is to

more directly control

plant architecture

for improvement of

agricultural yield in a

wide variety of diverse

growth conditions.

The ability of plant

cells to respond to signaling from other cells or the

environment depends on the proper localization of proteins

involved in transducing the signal within the plant cell. One

method the plant uses for protein localization is lipid post-

translational addition, such as prenylation, myristoylation,

and palmitoylation. The lipid moieties added in this process

aid in membrane targeting and association, allowing the

protein to carry out its proper function in the cell.

We have isolated plant mutants defective in protein

prenylation in order to study the global role this posttranslational modication plays in the plant, as well as its

role in the functions of target proteins and the identication

of the pathways in which those proteins act. Two enzymes

involved in protein prenylation, farnesyltransferase (PFT)

and geranylgeranyltranfserase-I (PGGT), are heterodimeric

enzymes that share a common alpha subunit but havedistinct beta subunits. We have now isolated plants with

mutations in all three subunits, and showed that alpha

subunit mutants (called pluripetala or plp) have severa

developmental defects, most notably abnormal meristem

function. They are also

more tolerant o

drought stress, as plp

plants can survive and

recover from extended

periods without water

In contrast, beta

subunit mutations

have much muchmilder phenotypes

suggesting an overlap

in the function of PFT

and PGGT.

We have identied

several prenylation

target proteins using

proteomics approaches

and in vitro assays

Several key signa

transduction proteinsare improperly

localized in cells ofplp

plants, distributed around the cytoplasm instead of being

plasma-membrane localized. There is also interplay among

the various types of prenylation and palmitoylation, with

the particular membrane localization depending on the

specic lipid groups present. Further studies are geared

toward investigating and characterizing novel proteins tha

may also be involved in lipid modication, and studying

the role of prenylation in crop plants, to see if its functiona

role is conserved and if it can be used to improve drough

tolerance and confer other benecial agronomic traits.


18/38The Donald Danorth Plant Science Center 2007 Scientifc Report16

Daniel Schachtman, Ph.D.Member

The main ocus o the lab is to identiy key mechanisms by which roots regulatemineral uptake and adapt to changing soil conditions such as drought and nutriendefciencies.

Lab Members:

Bertram Berla, BSc, Lab TechnicianEliana Gaitan, Ph.D., Postdoctoral AssociateKari Huppert, BSc, Research Associate

Jiyul Jung, Ph.D. StudentMin Jung Kim, Ph.D., Postdoctoral AssociateCathy Kromer, BSc, Administrative AssistantEllen Marsh, MSc, Senior Research AssociateSusana Munoz, Undergraduate Summer InternCarlos Ortiz, Undergraduate Summer InternRenu Pandey, PhD, Visiting ScientistRyoung Shin, Ph.D., Assistant Domain Member


Schachtman, DP and Shin, R. 2007. Nutrient Sensing and Signaling: NPKS,Annual Review of Plant Biology 58:47 69Shin, R, Burch, AY, Huppert, KA, Tiwari, SB, Murphy, AS, Guiloyle, TJ, Schachtman, DP (2007) TheArabidopsis transcription actor MYB77

modulates auxin signal transduction. The Plant Cell. 19:2440 - 2453.Shin, R, Alvarez, S., Burch, AY, Jez, JM, Schachtman, DP 2007. Phosphoproteomic Identifcation o Targets o theArabidopsis SNF-like Protein

Kinase SnRK2.8 Reveals a Connection to Metabolic Processes.Proc. Natl. Acad. Sci. U.S.A.104:6460 6465.Fung, RWM, Gonzalo, M, Fekete, C, Kovacs, LG, He, Y, Marsh, E, McIntyre, LM, Schachtman, DP, Qiu, W,. 2007. Transcriptional profling

reveals novel insights Into powdery mildew-induced deense response in grapevine. Plant Physiology. 146: 236-249.Fung, RWM, Qiu, W., Su, Y., Schachtman, DP, Huppert, K., Fekete, C., Kovacs, LG. 2007. Gene Expression Variation in Grapevine Species

Vitis vinifera L. and Vitis aestivalis Michx. Genetic Resources and Crop Evolution. 54:1541-1553.Jez, JM, Schachtman, DP, Berg, RH, Taylor, CG, Chen, S, Hicks, LM, Jaworski, JG, Smith, TJ, Nielsen, E, Pikaard, CS,. 2007. Developing a

New Interdisciplinary Lab Course or Undergraduate and Graduate Students: Plant Cells and Proteins. Biochemistry and MolecularBiology Education. 35:410-415.

Rosewarne GM, Smith FA, Schachtman DP, Smith SE. 2007. Localization o proton-ATPase genes expressed in arbuscular mycorrhizaltomato plants.Mycorrhiza. 14:249 - 258

Zhu, J., Alvarez, S., Marsh, E.L., LeNoble, M.E., Cho, I.J., Sivaguru, M., Chen, S., Nguyen, H.T., Wu, Y., Schachtman, D.P., Sharp, R.E. 2007.Cell wall proteome in the maize primary root elongation zone. Region-specifc changes in water soluble and lightly ionically-boundproteins under water defcit. Plant Physiology. 145: 1533-1548.

[email protected]

Nutrient sensing and signalingAims: Identiy components o the signal transductionnetworks involved in sensing and signaling changes in nutrientconcentrations in soils. Apply this knowledge to increasing thenutrient use eciency o crop plants.Background: Adaptation to changes in soil ertility is critical orcrop productivity and to reduce ertilizer usage, thereby decreasingwater pollution and increasing yield when soil ertility is low. It isnot known how plant roots sense or signal the changes that occurduring nutrient deciency.Progress: We studied the global regulation o gene expressionunder nutrient deciency in both Arabidopsis and corn roots.Using microarrays we identied genes and biochemical processesinvolved in the response to deciency. This work led to the

discovery that the signaling molecule hydrogen peroxide playsa role in response to nutrient deprivation in Arabidopsis roots.Two genes in Arabidopsis that are downregulated by potassiumdeprivation were studied in detail. We showed that the SnRK2.8kinase was linked to decreased growth through the regulationo metabolism. We also ound that MYB77 regulates lateral rootgrowth by modulating auxin signal transduction. Our work toelucidate nutrient signal transduction pathways continues withstudies on actors that are regulated by SnRK2.8 phosphorylationand through screening a promoter lucierase usion activationtagged library.

Increasing the bioavailability o zinc in cassavaBroad Aim: To increase the zinc content o cassava by six old.

Background: Cassava is a staple ood that is very low in vitamins,minerals and protein. Zinc is one o the most limiting micronutrientsin human diets. Zinc deciency reduces immunity and cognitiveabilities. The approach we are using is based on our previous workin which we increased the zinc content o seeds by overexpressiono ZIP1 (Ramesh, et al. 2004 Plant Mol Biol 54:373-385).Progress: We currently have generated over 150 transgenic lines andanalyzed the zinc content o the feshy edible part o the tuber in 60transgenic lines. We identied one line with over 800% higher and

six lines with between 150 350% higher zinc content. These lineseither express ZAT1 which is a vacuolar zinc transporter or ZIP1which is a plasma membrane zinc transporter whose expression isdriven by the patatin promoter. Lines that simultaneously express

both o these genes are also being generated and will be tested.

The molecular basis o powdery mildew resistance ingrapevinesBroad Aims: To understand the molecular basis o enhancedpowdery mildew resistance in native American grapevines andthe response to powdery mildew in the Vitis viniera varieties.Background: Missouri is a center o diversity or grapevinespecies and many o the vines that are endemic to Missouri have ahigher degree o resistance to ungal diseases than the commonly

cultivated Vitis viniera vines.Progress: This is a joint research project with scientists at MissouriState. Microarrays were used to ormulate the hypothesis that Vitisaestivalis cv. Norton is more resistant to powdery mildew than Vitisviniera cv. Cabernet Sauvignon because more deense genes areconstitutively activated. We will now study selected deense genesin the phenylpropenoid pathway to determine how this pathwayis regulated and how these metabolites impact disease resistance.


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Dilip M. Shah, Ph.D.Domain Associate Member

My research is focused on understanding the molecular mechanisms underlyinga plants defense against pathogens. We are investigating the modes of action ofantifungal plant defensins, mechanisms of fungal resistance to these proteins and thedevelopment of mycotoxin-free disease resistant crops.


Ramamoorthy, V., Zhao, X., Snyder, A.K., Xu, J-R., and Shah, D.M. 2007. Two mitogen-activated protein kinase signaling cascadesregulate sensitivity to antiungal plant deensins in Fusarium graminearum. Cellular Microbiology. 9, 1491-1506.

Allen, A., Snyder A.K., Preuss, M., Nielsen, E.E., Shah, D.M. and Smith, T.J. 2007. Plant deensins and ungal killer toxin KP4 inhibitroot growth. Planta. published online DOI 10.1007/s00425-007-0620-1

Ramamoorthy, V., Cahoon, E., Li, J. and Shah, D. M. 2007. Glucosylceramide synthase gene is essential or alala deensin-mediatedgrowth inhibition but not or pathogenicity o Fusarium graminearum. Molecular Microbiology . 66, 771-786.

Lab Members:Holly Carrell, Summer Intern

Jagdeep Kaur, Ph. D., Postdoctoral AssociateVellaisamy Ramamoorthy, Ph. D., Postdoctoral AssociateAnita K. Snyder, M.S., Research AssociateMercy Thokala, Ph. D., Postdoctoral Associate

[email protected]


Plant diseases caused by ungal pathogens are responsible orsubstantial losses o crop yield worldwide. Eective and sustainablecontrol o ungal pathogens remains one o the most importantchallenges o modern agriculture. The innate immune system oplants provides the frst line o deense against ungal pathogens.Small cysteine-rich antiungal proteins calleddeensins are ubiquitous plant proteins implicatedin the frst-line host deense against ungalpathogens. A better understanding o how theseproteins inhibit the growth o ungal pathogenswill lead to the development o novel strategiesor control o ungal diseases in transgenic crops.

Modes o Action o Plant Deensins: Plant

deensins are a amily o antiungal proteinswith remarkable structural conservation and richdiversity o variants. The constitutive expressiono these proteins in transgenic crops aords strongprotection rom ungal attack. A critical issue thatneeds to be addressed or eective use o theseproteins in transgenic crops is understanding theirmodes o action and the mechanisms by whichungal resistance to these proteins might emerge.My lab has been using Fusarium graminearum,a devastating multicellular flamentous ungalpathogen o wheat and barley, or deensinsmode(s) o action studies because genetic and

genomics tools are well developed in this organism. MsDe1 andMtDe4 are structurally similar deensins that share only 41% aminoacid identity and potently inhibit the growth oF. graminearum. MsDe1inhibits the growth o this ungus by inducing strong hyperbranchingeect , whereas MtDe4 does so by only limiting polar growth oungal hyphae (Figure 1). We have recently isolated several mutantsthat selectively exhibit hypersensitivity to MsDe1, but not to MtDe4.The molecular characterization o two o these mutants has revealedthat MAP kinase signaling cascades play a major role in regulatingsensitivity o F. graminearum to MsDe1, but not to MtDe4. The MAPkinase signaling cascades are essential or the ungus to protect itselrom these deensin. We have recently ound that MsDe1 binds toa ungal membrane sphingolipid glucosylceramide. Preliminaryevidence indicates that glucosylceramide is indeed a membranereceptor or MsDe1 whose absence results in resistance to MsDe1and a signifcant loss o ungal pathogenicity in wheat. We are in theprocess o characterizing structural determinants o glucosylceramide

receptor that are required or interaction with MsDe1. Our currenevidence indicates that MsDe1 and MtDe4 have dierent modes oantiungal action. Using newly isolated mutants o F. graminearumwe plan to identiy and subsequently characterize mutant genesconerring resistance to these deensins. These studies will be

complemented by microarray and proteomicanalyses o deensin-treated F. graminearumconidial cells to determine global gene expressionelicited by MsDe1 and MtDe4. These studieswill result in identifcation o unique cellularresponses to each deensin challenge in this ungusDisease Resistant Mycotoxin-Free Corn: In recenyears, ear rot disease caused by a ungal pathogenF. verticillioides has emerged as a major disease o

corn limiting yield. In addition to its direct negativeimpact on corn yield, the pathogen producesmycotoxins known as umonisins that have beenlinked to human and animal mycotoxicosisFumonisins pose a severe health hazard and theircontamination in corn constitutes a costly andchallenging problem. An environmentally soundand economical approach to address this problemis to plant corn hybrids that are highly resistantto ear rot. Genetically engineered ear rot resistantcorn will allow producers to generate high qualitymycotoxin-ree seed during normal as well asdisease-avoring growing seasons. We have ound

that plant deensins, MsDe1 and MtDe4, inhibit the growth o Fverticillioidesin vitro at micromolar concentrations. We have alreadydetermined that high level expression o these proteins in transgenicmodel plant Arabidopsis thaliana coners strong resistance to Fgraminearum, a pathogen o wheat and barley, which is closely relatedto F. verticillioides. We have constructed chimeric genes encodingMsDe1 and MtDe4 or high level expression in transgenic cornSeveral transgenic corn lines expressing either MsDe1 or MtDe4have been identifed. These lines will be tested or resistance to ungaldisease and control o mycotoxin contamination in the feld in 2008

Growth inhibition ofFusarium

graminearum fungus by antifungal

plant defensins, MsDef1 and MtDef4.

Note the striking hyperbranching of the

fungal hyphae observed with MsDef1

at concentration of 1.5 M and higher.

MtDef4 inhibits the growth of this

fungus without inducing hyperbranching

of hyphae.


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Thomas Smith, Ph.D.Member

My laboratory combines biochemistry and structural biology to elucidate a numbero biological problems.

Lab Members:Aron Allen, Lab TechnicianUmesh Katpally, Ph.D., Research AssociateNicole Koropatkin, Ph.D., Research AssociateMing Li, Ph.D., Research Associate

Administrative Assistant:Martha Shaer

[email protected]


Katpally, U., Wobus, C. E., Dryden, K., Virgin, H. W. IV, and Smith, T. J. 2008. Unexpected structural dierences between authenticnorovirus and virus like particles.J. Virol.

Kakani, K., Reade, R., Katpally, U., Smith, T. J., Rochon, D. 2008. Induction o particle polymorphism by Cucumber necrosis virus coatprotein in vivo.J. Virol.

Li, M., Allen, A., Smith, T. J. 2008. High throughput screening reveals several new classes o glutamate dehydrogenase inhibitors.Biochem.

Allen, A., Snyder, A. K., Preuss, M., Nielsen, E. E., Shah, D. M., Smith, T. J. 2008. Plant and virally encoded ungal toxins inhibit plantroot growth. Planta.

Koropatkin, N. M., Koppenaal, D. W., Pakrasi, H. B., Smith, T. J. 2007. The structure o a cyanobacterial bicarbonate transport protein,CmpA. J. Biol. Chem. 282: 2606-2614.

Goncalves, R. B., Mendes, Y. S., Soares, M. R., Katpally, U., Smith, T. J., Silva, J. L., Oliveira, A. C. 2007. VP4 protein rom humanrhinovirus 14 is released by pressure and locked in the capsid by the antiviral compound WIN. J. Mol. Biol. 366: 295-306.

Asurmendi, S., Berg, R. H., Smith, T. J., Bendhamane, M., Beachy, R. N. 2007. Aggregation o TMV CP plays a role in CP unctions andin coat-protein mediated resistance. Virology. 336:98-106.

Wei, B., Randich, A. M., Bhattacharyya-Pakrasi, M., Pakrasi, H. B., Smith, T. J. 2007. Possible regulatory role or the histidine-rich loopin the zinc transport protein, ZnuA. Biochemistry. 46: 8734-8743.

Katpally, U., Smith, T. J. 2007. Pocket actors unlikely play a major role in the lie cycle o human rhinovirus. J. Virol. 81: 6307-6315.Jez, J., Schachtman, D. P., Berg, R. H., Taylor, C. G., Chen, S., Hicks, L. M., Smith, T. J., Nielsen, E., Pikaard, C. S. 2007. Developing a

new interdisciplinary lab course or undergraduate and graduate students: plant cells and proteins. Biochem. and Mol. Biol. Edu.35:410-415.

Koropatkin, N. M., Randich, A. M., Bhattacharyya-Pakrasi, M., Pakrasi, H. B., Smith, T. J. 2007. The structure o the iron bindingprotein, FutA1, rom Synechocystis 6803.J. Biol. Chem. 282:27468-27477.

Human rhinovirus: To create the next generation o vaccines,we need to better understand how antibodies neutralize virusesand what processes could be blocked by antibodies. To thatend, we have determined the structures o several neutralizingantibodies and antibody/virus complexes and have used massspectroscopy to monitor the dynamic processes involved in therelease o the viral genome into the target cell. These studies areacilitating the development o synthetic vaccines that might bedisplayed on plant viruses and are changing our view o earlysteps in the viral inection process.Glutamate dehydrogenase (GDH): Found in all organisms,GDH catalyzes the catabolism o glutamate. Unlike GDH romother organisms, animal GDH exhibits extremely complex

regulation by a number o cellular compounds. Our recentcollaborative work has suggested that this complex allostericregulation evolved in animals to, at least in part, control insulinsecretion. This nding has led to the preliminary identicationo some plant natural products that may be useul in thetreatment o insulin disorders.

Fungal toxins: In collaboration with Dr. Dilip Shah at theDanorth Center, we have shown that some o the plantdeensins act in manner similar to our previously studiedungal toxin, KP4. These results suggest a possible broader roleo these proteins in plants and may be useul in controllingungal inection o ood crops. This could not only increase yield

but could deter contamination o grains by ungi that producecancer-causing mycotoxins.

Nutrient transport: All organisms have pumps on their outersuraces to take in essential nutrients such as metals, nitrate,and bicarbonate. To better understand this process, we havedetermined the structure o parts o several transporters thauses energy rom ATP to drive import. We have also determinedthe structures o proteins rom gut bacteria essential to therecognition and processing o starches and polysaccarides.

Virus Structure: Using a combination o cryo-electronmicroscopy and crystallography we examine the structure andunction o several animal and plant viruses such as cucumbermosaic virus, cucumber necrosis virus, and murine norovirus.



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Christopher Taylor, Ph.D.Assistant Member

My laboratorys ocus is on the role o biotrophic parasites o plant roots.

Lab Members:Pricilla Alaro; REU Undergraduate InternHaytham Aly; Graduate Student

Jennier Berendzen; RET High School Teacher InternValentina Carballo; Graduate StudentKathleen Dwyer, High School Teacher Intern

James (Mitch) Elmore; Lab TechnicianThomas Fester, Ph.D.; Post Doctoral AssociateManjula Govindarajulu; Ph.D., Post Doctoral AssociateLeslie Johnson; High School Student Intern

Joe Kamalay, Ph.D.; Post Doctoral AssociateAravinth Karunanandaa; High School Student InternMichelle Kim; Lab TechnicianPat Kohleld; REU Undergraduate InternYuhong Li, Ph.D.; Post Doctoral AssociateHeather Marella, Ph.D.; Post Doctoral AssociateKim Morrell; Undergraduate Intern

Zhi Qi, Ph.D.; Post Doctoral AssociateLaura Schoenlaub; Undergraduate InternVeena Veena, Ph.D.; Post Doctoral Associate

[email protected]

Plant-parasitic nematodes are among the most destructive plantpests, causing substantial economic losses to crops worldwide. TheUSDAs Committee on National Needs and Priorities in Nematologyestimated the value o plant damage associated with nematodes inthe U.S. at $7 to 9 billion annually. Current methods o controllingnematodes have met with limited success. Breeding or resistancecan be an eective deense against plant-parasitic nematodes butsources o broad resistance are not available or many crops and theresistance is not always durable. Chemical control o nematodeshas proven to be eective; however, most nematicides used to datehave serious saety and environmental drawbacks and many have

been removed rom the market. These concerns have accentuatedthe need or new methods or nematode control.

Based on the paradigm established or insect control using Bacillusthuringienesis (B.t.s), one successul approach to nematode control isto identiy plant-associated bacteria that are lethal to plant-parasiticnematodes. In my laboratory, a collection o over 12,000 microbialisolates was screened against the ree-living nematode, Caenorhabditiselegans. Approximately 150 isolates were conrmed to be lethal tothis model nematode. O the lethal isolates, 63 were identied as

belonging to the Pseudomonasgenus o bacteria. In plate assays, one-third o the C. elegans-lethal Pseudomonas isolates were ound to belethal to plant-parasitic nematodes. Soil bioassays have shown thatseveral o these nematode-lethal Pseudomonas isolates have plant-protective activity against plant-parasitic nematodes.

Members o the Pseudomonas genus o bacteria have been well

characterized or their plant-growth promoting activities, theirability to colonize plant roots, and or their use as biocontrol agentso ungal diseases in plants. Biocontrol strains o Pseudomonas have

been examined or their ability to produce numerous secondarymetabolites with biocontrol activity including phenazines,polyketides, phloroglucinols and hydrogen cyanide. Virtuallynothing is known about how Pseudomonascan inhibit plant-parasiticnematodes.

We have characterized our nematode-active Pseudomonas isolatesor exoprotease activity, siderophore production, motility,polysaccharide production, fuorescence and production o small

biocontrol molecules to determine i commonalities exist among thenematode-lethal isolates. We have generated several transposon

mutagenized libraries o nematode-lethal strains oPseudomonasin anattempt to identiy non-lethal mutants. Analysis o non-nematode-

lethal transposon-tagged mutants o Pseudomonas isolate 15G2identied genes involved in hydrogen cyanide (HCN) productionand regulation. From our nematode-lethal collection oPseudomonasseveral o the isolates were ound to be HCN producers indicatingthat HCN may be an important indicator molecule or biocontroo plant-parasitic nematodes. We are currently investigating howPseudomonas produce HCN, how they attack and kill nematodesand whether these isolates can colonize plant roots and promoteplant growth. Understanding the range and modes o nematode-inhibiting activities o these plant-associated bacteria will providea better understanding o how to recruit these useul bacteria to theplant or protection rom plant-parasitic nematodes.


Fester, T., Berg, R.H. and Taylor, C.G. 2007. An easy method or the microscopic analysis o plant biotrophic interactions. Journal oMicroscopy.

Veena and Taylor, C.G. 2007. Agrobacterium rhizogenes: recent developments and promising applications. In vitro Cell. Devel. Biol. Plant 43:383-403.

Jez, J.M., Schachtman, D.P., Berg, R.H., Taylor C.G., Chen, S., Hicks, L.M., Jaworski, J.G., Smith, T.J., Nielsen, E. and Pikaard, C.S. 2007.

Developing a new interdisciplinary lab course for undergraduate and graduate students: plant cells and proteins.Biochem. Mol. Biol. Educ.

35:410-416.


Fluorescence of nematode-lethal isolates ofPseudomonas.


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The tropical root crop cassava ( Manihot esculenta) is o centralimportance to ood security and local economies throughout thetropics, most especially in Arica. Research in our laboratoryutilizes transgenic technologies to addresses two o the mostimportant constraints to cassava production and utilization susceptibility to virus disease and poor nutritional content ooodstus derived rom the cassava root.

With support rom the United States Agency or InternationalDevelopment (USAID), we have continued to develop transgenictechnologies aimed at generating resistance to cassava mosaicdisease (CMD), the major viral disease o this crop in Arica. Inaddition, 2006 saw the commencement o a major project supported

by the Monsanto Fund to produce virus resistant cassava or

Uganda and Malawi. The Virus Resistant Cassava (VIRCA)project presents a special and exciting challenge or a publicsector organization such as the Danorth Plant Science Centerto deliver a transgenic product to armers in East and SouthernArica. During 2006, a team o around a dozen researchers wasassembled, a transgenic plant production system implementedand high throughput analytical systems developed to allow theregeneration and study o many 100s o transgenic cassava plantseach year.

Transgenic technologiesare being employed togenerate cassava plantswith elevated resistance

to CMD through bothRNA (gene silencing)and protein basedtechnologies. Newgenerations o transgenicplants were produced in2006 utilizing improvedversions o both strategies.While initial screeningor enhanced resistanceis perormed within thegreenhouse acilities atthe Danorth Center, feldtrials in East Arica are

an essential componento our eorts to developand deliver improved cassava to E

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Rita Gollihur