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2004

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University of Nebraska - Lincoln

Faculty Publications from the Center for Plant Science Innovation

Articles 1 - 7 of 7

Full-Text Articles in Life Sciences

Tandem Inverted Repeat System For Selection Of Effective Transgenic Rnai Strains In Chlamydomonas, Jennifer Rohr, Nandita Sarkar, Susan Belanger, Byeong-Ryool Jeong, Heriberto D. Cerutti Nov 2004

Tandem Inverted Repeat System For Selection Of Effective Transgenic Rnai Strains In Chlamydomonas, Jennifer Rohr, Nandita Sarkar, Susan Belanger, Byeong-Ryool Jeong, Heriberto D. Cerutti

Faculty Publications from the Center for Plant Science Innovation

RNA interference (RNAi), the double-stranded RNA (dsRNA) triggered post-transcriptional gene silencing, is becoming a powerful tool for reverse genetics studies. Stable RNAi, induced by the expression of inverted repeat (IR) transgenes, has been achieved in protozoa, algae, fungi, plants, and metazoans. However, the level of gene silencing is often quite variable, depending on the type of construct, transgene copy number, site of integration, and target gene. This is a hindrance in functional genomics studies, where it is desirable to suppress target genes reliably to analyze unknown phenotypes. Consequently, we explored strategies for direct selection of effective transgenic RNAi lines in ...


Folate Biofortification In Tomatoes By Engineering The Pteridine Branch Of Folate Synthesis, Rocio Diaz De La Garza, Eoin P. Quinlivan, Sebastian M. J. Klaus, Gilles J. C. Basset, Jesse F. Gregory Iii, Andrew D. Hanson Sep 2004

Folate Biofortification In Tomatoes By Engineering The Pteridine Branch Of Folate Synthesis, Rocio Diaz De La Garza, Eoin P. Quinlivan, Sebastian M. J. Klaus, Gilles J. C. Basset, Jesse F. Gregory Iii, Andrew D. Hanson

Faculty Publications from the Center for Plant Science Innovation

Plants are the main source of folate in human diets, but many fruits, tubers, and seeds are poor in this vitamin, and folate deficiency is a worldwide problem. Plants synthesize folate from pteridine, p-aminobenzoate (PABA), and glutamate moieties. Pteridine synthesis capacity is known to drop in ripening tomato fruit; therefore, we countered this decline by fruit-specific overexpression of GTP cyclohydrolase I, the first enzyme of pteridine synthesis. We used a synthetic gene based on mammalian GTP cyclohydrolase I, because this enzyme is predicted to escape feedback control in planta. This engineering maneuver raised fruit pteridine content by 3- to ...


Disabling Surveillance: Bacterial Type Iii Secretion System Effectors That Suppress Innate Immunity, Avelina Espinosa, James R. Alfano Aug 2004

Disabling Surveillance: Bacterial Type Iii Secretion System Effectors That Suppress Innate Immunity, Avelina Espinosa, James R. Alfano

Faculty Publications from the Center for Plant Science Innovation

Many Gram-negative bacterial pathogens of plants and animals are dependent on a type III protein secretion system (TTSS). TTSSs translocate effector proteins into host cells and are capable of modifying signal transduction pathways. The innate immune system of eukaryotes detects the presence of pathogens using specific pathogen recognition receptors (PRRs). Plant PRRs include the FLS2 receptor kinase and resistance proteins. Animal PRRs include Tolllike receptors and nucleotide-binding oligomerization domain proteins. PRRs initiate signal transduction pathways that include mitogen-activated protein kinase (MAPK) cascades that activate defencerelated transcription factors. This results in induction of proinflammatory cytokines in animals, and hallmarks of defence ...


The Pseudomonas Syringae Hopptov Protein Is Secreted In Culture And Translocated Into Plant Cells Via The Type Iii Protein Secretion System In A Manner Dependent On The Shcv Type Iii Chaperone, Misty D. Wehling, Ming Guo, Zheng Qing Fu, James R. Alfano Jun 2004

The Pseudomonas Syringae Hopptov Protein Is Secreted In Culture And Translocated Into Plant Cells Via The Type Iii Protein Secretion System In A Manner Dependent On The Shcv Type Iii Chaperone, Misty D. Wehling, Ming Guo, Zheng Qing Fu, James R. Alfano

Faculty Publications from the Center for Plant Science Innovation

The bacterial plant pathogen Pseudomonas syringae depends on a type III protein secretion system and the effector proteins that it translocates into plant cells to cause disease and to elicit the defense-associated hypersensitive response on resistant plants. The availability of the P. syringae pv. tomato DC3000 genome sequence has resulted in the identification of many novel effectors. We identified the hopPtoV effector gene on the basis of its location next to a candidate type III chaperone (TTC) gene, shcV, and within a pathogenicity island in the DC3000 chromosome. A DC3000 mutant lacking ShcV was unable to secrete detectable amounts of ...


Evaluation Of The Escherichia Coli Threonine Deaminase Gene As A Selectable Marker For Plant Transformation, A. Ebmeier, L. Allison, Heriberto D. Cerutti, Thomas E. Clemente Apr 2004

Evaluation Of The Escherichia Coli Threonine Deaminase Gene As A Selectable Marker For Plant Transformation, A. Ebmeier, L. Allison, Heriberto D. Cerutti, Thomas E. Clemente

Faculty Publications from the Center for Plant Science Innovation

The initial step in the synthesis of isoleucine (Ile) is the conversion of threonine to α-ketobutyrate. This reaction is carried out by threonine deaminase (TD), which is feedback-regulated by Ile. Mutations in TD that manifest insensitivity to Ile feedback inhibition result in intracellular accumulation of Ile. Previous reports have shown that in planta expression of the wild-type Escherichia coli TD, ilvA, or an Ile-insensitive mutant designated ilvA-466, increased cellular concentrations of Ile. A structural analog of Ile, L-O-methylthreonine (OMT), is able to compete effectively with Ile during translation and induce cell death. It has been postulated that OMT could therefore ...


Folate Synthesis In Plants: The P-Aminobenzoate Branch Is Initiated By A Bifunctional Paba–Pabb Protein That Is Targeted To Plastids, Gilles J. C. Basset, Eoin P. Quinlivan, Stéphane Ravanel, Fabrice Rébeillé, Brian P. Nichols, Kazuo Shinozaki, Motoaki Seki, Lori C. Adams-Phillips, James J. Giovannoni, Jesse F. Gregory Iii, Andrew D. Hanson Jan 2004

Folate Synthesis In Plants: The P-Aminobenzoate Branch Is Initiated By A Bifunctional Paba–Pabb Protein That Is Targeted To Plastids, Gilles J. C. Basset, Eoin P. Quinlivan, Stéphane Ravanel, Fabrice Rébeillé, Brian P. Nichols, Kazuo Shinozaki, Motoaki Seki, Lori C. Adams-Phillips, James J. Giovannoni, Jesse F. Gregory Iii, Andrew D. Hanson

Faculty Publications from the Center for Plant Science Innovation

It is not known how plants synthesize the p-aminobenzoate (PABA) moiety of folates. In Escherichia coli, PABA is made from chorismate in two steps. First, the PabA and PabB proteins interact to catalyze transfer of the amide nitrogen of glutamine to chorismate, forming 4-amino-4-deoxychorismate (ADC). The PabC protein then mediates elimination of pyruvate and aromatization to give PABA. Fungi, actinomycetes, and Plasmodium spp. also synthesize PABA but have proteins comprising fused domains homologous to PabA and PabB. These bipartite proteins are commonly called ‘‘PABA synthases,’’ although it is unclear whether they produce PABA or ADC. Genomic approaches identified Arabidopsis ...


Pseudomonas Syringae Type Iii Secretion System Targeting Signals And Novel Effectors Studied With A Cya Translocation Reporter, Lisa M. Schechter, Kathy A. Roberts, Yashitola Jamir, James R. Alfano, Alan Collmer Jan 2004

Pseudomonas Syringae Type Iii Secretion System Targeting Signals And Novel Effectors Studied With A Cya Translocation Reporter, Lisa M. Schechter, Kathy A. Roberts, Yashitola Jamir, James R. Alfano, Alan Collmer

Faculty Publications from the Center for Plant Science Innovation

Pseudomonas syringae pv. tomato strain DC3000 is a pathogen of tomato and Arabidopsis. The hrp-hrcencoded type III secretion system (TTSS), which injects bacterial effector proteins (primarily called Hop or Avr proteins) into plant cells, is required for pathogenicity. In addition to being regulated by the HrpL alternative sigma factor, most avr or hop genes encode proteins with N termini that have several characteristic features, including (i) a high percentage of Ser residues, (ii) an aliphatic amino acid (Ile, Leu, or Val) or Pro at the third or fourth position, and (iii) a lack of negatively charged amino acids ...