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Dr. C. Korsi Dumenyo
Tennessee State University Inst. of Agricultural & Environmental Research

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0 Environmental microbiology, and biotechnology
0 Soft rot
0 Pectobacterium
0 Pathogen genes
0 Pathogenic microbes

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Pectobacterium
Soft rot

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Journal article
Published: 06 August 2021 in Nanomaterials
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While multi-drug resistance in bacteria is an emerging concern in public health, using carbon dots (CDs) as a new source of antimicrobial activity is gaining popularity due to their antimicrobial and non-toxic properties. Here we prepared carbon dots from citric acid and β-alanine and demonstrated their ability to inhibit the growth of diverse groups of Gram-negative bacteria, including E. coli, Salmonella, Pseudomonas, Agrobacterium, and Pectobacterium species. Carbon dots were prepared using a one-pot, three-minute synthesis process in a commercial microwave oven (700 W). The antibacterial activity of these CDs was studied using the well-diffusion method, and their minimal inhibitory concentration was determined by exposing bacterial cells for 20 h to different concentrations of CDs ranging from 0.5 to 10 mg/mL. Our finding indicates that these CDs can be an effective alternative to commercially available antibiotics. We also demonstrated the minimum incubation time required for complete inhibition of bacterial growth, which varied depending on bacterial species. With 15-min incubation time, A. tumefaciens and P. aeruginosa were the most sensitive strains, whereas E. coli and S. enterica were the most resistant bacterial strains requiring over 20 h incubation with CDs.

ACS Style

Anju Pandey; Asmita Devkota; Zeinab Yadegari; Korsi Dumenyo; Ali Taheri. Antibacterial Properties of Citric Acid/β-Alanine Carbon Dots against Gram-Negative Bacteria. Nanomaterials 2021, 11, 2012 .

AMA Style

Anju Pandey, Asmita Devkota, Zeinab Yadegari, Korsi Dumenyo, Ali Taheri. Antibacterial Properties of Citric Acid/β-Alanine Carbon Dots against Gram-Negative Bacteria. Nanomaterials. 2021; 11 (8):2012.

Chicago/Turabian Style

Anju Pandey; Asmita Devkota; Zeinab Yadegari; Korsi Dumenyo; Ali Taheri. 2021. "Antibacterial Properties of Citric Acid/β-Alanine Carbon Dots against Gram-Negative Bacteria." Nanomaterials 11, no. 8: 2012.

Original article
Published: 24 October 2020 in Letters in Applied Microbiology
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We re‐engineered a classic tool for mutagenesis and gene expression studies in Gram‐negative bacteria. Our modified Tn5‐based transposon contains multiple features that allow rapid selection for mutants, direct quantification of gene expression, and straightforward cloning of the inactivated gene. The promoter‐less gfp‐km cassette provides selection and reporter assay depending on the activity of the promoter upstream of the transposon insertion site. The cat gene facilitates positive antibiotic selection for mutants, while the narrow R6Kγ replication origin forces transposition in recipient strains lacking the pir gene and enables cloning the transposon flanked with the disrupted gene from the chromosome. The suicide vector pCKD100, a plasmid that could be delivered into recipient cells through bi‐parental mating or electroporation, harbors the modified transposon. We used the transposon to mutagenize Pectobacterium versatile KD100, Pseudumonas coronafaciens PC27R, and Escherichia coli 35150N. The fluorescence intensities of mutants expressing high GFP could be quantified and detected qualitatively. Transformation efficiency from conjugation ranged from 1600 to 1900 CFU ml‐1. We sequenced the upstream flanking regions, identified the putative truncated genes, and demonstrated the restoration of the GFP phenotype through marker exchange. The mini‐Tn5 transposon was also utilized to construct mutant library of P. versatile for forward genetic screens.

ACS Style

Eric S. Nazareno; Bimala Acharya; C. Korsi Dumenyo. A mini‐Tn5‐derived transposon with reportable and selectable markers enables rapid generation and screening of insertional mutants in Gram‐negative bacteria. Letters in Applied Microbiology 2020, 72, 283 -291.

AMA Style

Eric S. Nazareno, Bimala Acharya, C. Korsi Dumenyo. A mini‐Tn5‐derived transposon with reportable and selectable markers enables rapid generation and screening of insertional mutants in Gram‐negative bacteria. Letters in Applied Microbiology. 2020; 72 (3):283-291.

Chicago/Turabian Style

Eric S. Nazareno; Bimala Acharya; C. Korsi Dumenyo. 2020. "A mini‐Tn5‐derived transposon with reportable and selectable markers enables rapid generation and screening of insertional mutants in Gram‐negative bacteria." Letters in Applied Microbiology 72, no. 3: 283-291.

Journal article
Published: 02 March 2020 in Microorganisms
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Pectobacterium and Dickeya species, usually referred to as soft rot Enterobacteriaceae, are phytopathogenic genera of bacteria that cause soft rot and blackleg diseases and are responsible for significant yield losses in many crops across the globe. Diagnosis of soft rot disease is difficult through visual disease symptoms. Pathogen detection and identification methods based on cultural and morphological identification are time-consuming and not always reliable. A polymerase chain reaction (PCR)-based detection method with the species-specific primers is fast and reliable for detecting soft rot pathogens. We have developed a specific and sensitive detection system for some species of soft rot Pectobacteriaceae pathogens in the Pectobacterium and Dickeya genera based on the use of species-specific primers to amplify unique genomic segments. The specificities of primers were verified by PCR analysis of genomic DNA from 14 strains of Pectobacterium, 8 strains of Dickeya, and 6 strains of non-soft rot bacteria. This PCR assay provides a quick, simple, powerful, and reliable method for detection of soft rot bacteria.

ACS Style

Niamul Kabir; Ali Taheri; C. Korsi Dumenyo. Development of PCR-Based Detection System for Soft Rot Pectobacteriaceae Pathogens Using Molecular Signatures. Microorganisms 2020, 8, 358 .

AMA Style

Niamul Kabir, Ali Taheri, C. Korsi Dumenyo. Development of PCR-Based Detection System for Soft Rot Pectobacteriaceae Pathogens Using Molecular Signatures. Microorganisms. 2020; 8 (3):358.

Chicago/Turabian Style

Niamul Kabir; Ali Taheri; C. Korsi Dumenyo. 2020. "Development of PCR-Based Detection System for Soft Rot Pectobacteriaceae Pathogens Using Molecular Signatures." Microorganisms 8, no. 3: 358.

Journal article
Published: 10 February 2020 in Horticulturae
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Soft rot bacteria of the Pectobacterium and Dickeya genera are Gram-negative phytopathogens that produce and secrete plant cell wall-degrading enzymes (PCWDE), the actions of which lead to rotting and decay of their hosts in the field and in storage. Host chemical signals are among the factors that induce the bacteria into extracellular enzyme production and virulence. A class of compounds (Class I) made up of intermediate products of cell wall (pectin) degradation induce exoenzyme synthesis through KdgR, a global negative regulator of exoenzyme production. While the KdgR− mutant of P. carotovorum is no longer inducible by Class I inducers, we demonstrated that exoenzyme production is induced in this strain in the presence of extracts from hosts including celery, potato, carrot, and tomato, suggesting that host plants contain another class of compounds (Class II inducers) different from the plant cell wall-degradative products that work through KdgR. The Class II inducers are thermostable, water-soluble, diffusible, and dialysable through 1 kDa molecular weight cut off pore size membranes, and could be a target for soft rot disease management strategies.

ACS Style

Paul A. Agyemang; Niamul Kabir; Caleb M. Kersey; C. Korsi Dumenyo. The Bacterial Soft Rot Pathogens, Pectobacterium carotovorum and P. atrosepticum, Respond to Different Classes of Virulence-Inducing Host Chemical Signals. Horticulturae 2020, 6, 13 .

AMA Style

Paul A. Agyemang, Niamul Kabir, Caleb M. Kersey, C. Korsi Dumenyo. The Bacterial Soft Rot Pathogens, Pectobacterium carotovorum and P. atrosepticum, Respond to Different Classes of Virulence-Inducing Host Chemical Signals. Horticulturae. 2020; 6 (1):13.

Chicago/Turabian Style

Paul A. Agyemang; Niamul Kabir; Caleb M. Kersey; C. Korsi Dumenyo. 2020. "The Bacterial Soft Rot Pathogens, Pectobacterium carotovorum and P. atrosepticum, Respond to Different Classes of Virulence-Inducing Host Chemical Signals." Horticulturae 6, no. 1: 13.

Preprint
Published: 22 July 2019
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One of the most important tools in genetic improvement is mutagenesis, which is a useful tool to induce genetic and phenotypic variation for trait improvement and discovery of novel genes. JTN-5203 (MG V) mutant population was generated using an induced ethyl methane sulfonate (EMS) mutagenesis and was used for detection of induced mutations in FAD2-1A and FAD2-1B genes using reverse genetics approach. Optimum concentration of EMS was used to treat 15,000 bulk JTN-5203 seeds producing 1,820 M2 population. DNA was extracted, normalized, and pooled from these individuals. Specific primers were designed from FAD2-1A and FAD2-1B genes that are involved in the fatty acid biosynthesis pathway for further analysis using next-generation sequencing. High throughput mutation discovery through TILLING-by-Sequencing approach was used to detect novel allelic variations in this population. Several mutations and allelic variations with high impacts were detected for FAD2-1A and FAD2-1B. This includes GC to AT transition mutations in FAD2-1A (20%) and FAD2-1B (69%). Mutation density for this population is estimated to be about 1/136kb. Through mutagenesis and high-throughput sequencing technologies, novel alleles underlying the mutations observed in mutants with reduced polyunsaturated fatty acids will be identified, and these mutants can be further used in breeding soybean lines with improved fatty acid profile, thereby developing heart-healthy-soybeans.

ACS Style

Reneth Millas; Mary Jane Espina; Cm Sabbir Ahmed; Angelina Bernardini; Ekundayo Adeleke; Zeinab Yadegari; Korsi Dumenyo; Ali Taheri. Detection of novel allelic variations in soybean mutant population using Tilling by Sequencing. 2019, 1 .

AMA Style

Reneth Millas, Mary Jane Espina, Cm Sabbir Ahmed, Angelina Bernardini, Ekundayo Adeleke, Zeinab Yadegari, Korsi Dumenyo, Ali Taheri. Detection of novel allelic variations in soybean mutant population using Tilling by Sequencing. . 2019; ():1.

Chicago/Turabian Style

Reneth Millas; Mary Jane Espina; Cm Sabbir Ahmed; Angelina Bernardini; Ekundayo Adeleke; Zeinab Yadegari; Korsi Dumenyo; Ali Taheri. 2019. "Detection of novel allelic variations in soybean mutant population using Tilling by Sequencing." , no. : 1.

Journal article
Published: 13 June 2019 in Microorganisms
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Pectobacterium carotovorum is a gram-negative bacterium that, together with other soft rot Enterobacteriaceae causes soft rot disease in vegetables, fruits, and ornamental plants through the action of exoproteins including plant cell wall-degrading enzymes (PCWDEs). Although pathogenicity in these bacteria is complex, virulence levels are proportional to the levels of plant cell wall-degrading exoenzymes (PCWDEs) secreted. Two low enzyme-producing transposon Tn5 mutants were isolated, and compared to their parent KD100, the mutants were less virulent on celery petioles and carrot disks. The inactivated gene responsible for the reduced virulence phenotype in both mutants was identified as wcaG. The gene, wcaG (previously denoted fcl) encodes NAD-dependent epimerase/dehydratase, a homologue of GDP-fucose synthetase of Escherichia coli. In Escherichia coli, GDP-fucose synthetase is involved in the biosynthesis of the exopolysaccharide, colanic acid (CA). The wcaG mutants of P. carotovorum formed an enhanced level of biofilm in comparison to their parent. In the hydrophobicity test the mutants showed more hydrophobicity than the parent in hexane and hexadecane as solvents. Complementation of the mutants with extrachromosomal copies of the wild type gene restored these functions to parental levels. These data indicate that NAD-dependent epimerase/dehydratase plays a vital rule in cell surface properties, exoenzyme production, and virulence in P. carotovorum.

ACS Style

Rabiul Islam; Shyretha Brown; Ali Taheri; C. Korsi Dumenyo. The Gene Encoding NAD-Dependent Epimerase/Dehydratase, wcaG, Affects Cell Surface Properties, Virulence, and Extracellular Enzyme Production in the Soft Rot Phytopathogen, Pectobacteriumcarotovorum. Microorganisms 2019, 7, 172 .

AMA Style

Rabiul Islam, Shyretha Brown, Ali Taheri, C. Korsi Dumenyo. The Gene Encoding NAD-Dependent Epimerase/Dehydratase, wcaG, Affects Cell Surface Properties, Virulence, and Extracellular Enzyme Production in the Soft Rot Phytopathogen, Pectobacteriumcarotovorum. Microorganisms. 2019; 7 (6):172.

Chicago/Turabian Style

Rabiul Islam; Shyretha Brown; Ali Taheri; C. Korsi Dumenyo. 2019. "The Gene Encoding NAD-Dependent Epimerase/Dehydratase, wcaG, Affects Cell Surface Properties, Virulence, and Extracellular Enzyme Production in the Soft Rot Phytopathogen, Pectobacteriumcarotovorum." Microorganisms 7, no. 6: 172.

Journal article
Published: 27 February 2018 in Journal of Phytopathology
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Pathogenesis by Pectobacterium carotovorum and the other soft rot bacteria results mostly from the synthesis and secretion of a plethora of exoproteins including plant cell wall-degrading enzymes and type III effectors. A mini-Tn5 transposon mutant of P. carotovorum (KD200) was isolated that is highly increased in activity and transcript levels of extracellular cell wall-degradative enzymes, pectate lyase, polygalacturonase, cellulase and protease. Accordingly, the mutant was more virulent as it macerated more host tissue than its parent. KD200 mutant harbours a Tn5 insertion directly upstream of nssAEcc71, a putative sodium/sulphate symporter gene and member of a family of divalent anion sodium symporters (DASS). The findings reported here suggest that DASS proteins may be involved in soft rot pathogenesis.

ACS Style

Caleb M. Kersey; Darren Heintzman; C. Korsi Dumenyo. Transposon insertion upstream of a putative sodium/sulphate symporter is associated with hypervirulence in the soft rot bacterium, Pectobacterium carotovorum. Journal of Phytopathology 2018, 166, 365 -371.

AMA Style

Caleb M. Kersey, Darren Heintzman, C. Korsi Dumenyo. Transposon insertion upstream of a putative sodium/sulphate symporter is associated with hypervirulence in the soft rot bacterium, Pectobacterium carotovorum. Journal of Phytopathology. 2018; 166 (5):365-371.

Chicago/Turabian Style

Caleb M. Kersey; Darren Heintzman; C. Korsi Dumenyo. 2018. "Transposon insertion upstream of a putative sodium/sulphate symporter is associated with hypervirulence in the soft rot bacterium, Pectobacterium carotovorum." Journal of Phytopathology 166, no. 5: 365-371.

Journal article
Published: 01 December 2016 in Physiological and Molecular Plant Pathology
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ACS Style

Eric S. Nazareno; Caleb M. Kersey; C. Korsi Dumenyo. Characterization of the incompatible interaction between Erwinia tracheiphila and non-host tobacco (Nicotiana tabacum). Physiological and Molecular Plant Pathology 2016, 96, 85 -93.

AMA Style

Eric S. Nazareno, Caleb M. Kersey, C. Korsi Dumenyo. Characterization of the incompatible interaction between Erwinia tracheiphila and non-host tobacco (Nicotiana tabacum). Physiological and Molecular Plant Pathology. 2016; 96 ():85-93.

Chicago/Turabian Style

Eric S. Nazareno; Caleb M. Kersey; C. Korsi Dumenyo. 2016. "Characterization of the incompatible interaction between Erwinia tracheiphila and non-host tobacco (Nicotiana tabacum)." Physiological and Molecular Plant Pathology 96, no. : 85-93.

Journal article
Published: 01 December 2015 in Microbial Pathogenesis
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We conducted a greenhouse trial to determine specific compatible interactions between Erwinia tracheiphila strains and cucurbit host species. Using a modified inoculation system, E. tracheiphila strains HCa1-5N, UnisCu1-1N, and MISpSq-N were inoculated to cucumber (Cucumis sativus) cv. ‘Sweet Burpless’, melon (Cucumis melo) cv. ‘Athena Hybrid’, and squash (Cucubita pepo) cv. ‘Early Summer Crookneck’. We observed symptoms and disease progression for 30 days; recorded the number of days to wilting of the inoculated leaf (DWIL), days to wilting of the whole plant (DWWP), and days to death of the plant (DDP). We found significant interactions between host cultivar and pathogen strains, which imply host specificity. Pathogen strains HCa1-5N and UnisCu1-1N isolated from Cucumis species exhibited more virulence in cucumber and melon than in squash, while the reverse was true for strain MISpSq-N, an isolate from Cucurbita spp. Our observations confirm a previous finding that E. tracheiphila strains isolated from Cucumis species were more virulent on Cucumis hosts and those from Cucubita were more virulent on Cucubita hosts. This confirmation helps in better understanding the pathosystem and provides baseline information for the subsequent development of new disease management strategies for bacterial wilt. We also demonstrated the efficiency of our modified inoculation and disease scoring methods.

ACS Style

Eric S. Nazareno; C. Korsi Dumenyo. Modified inoculation and disease assessment methods reveal host specificity in Erwinia tracheiphila-Cucurbitaceae interactions. Microbial Pathogenesis 2015, 89, 184 -187.

AMA Style

Eric S. Nazareno, C. Korsi Dumenyo. Modified inoculation and disease assessment methods reveal host specificity in Erwinia tracheiphila-Cucurbitaceae interactions. Microbial Pathogenesis. 2015; 89 ():184-187.

Chicago/Turabian Style

Eric S. Nazareno; C. Korsi Dumenyo. 2015. "Modified inoculation and disease assessment methods reveal host specificity in Erwinia tracheiphila-Cucurbitaceae interactions." Microbial Pathogenesis 89, no. : 184-187.

Journal article
Published: 01 January 2014 in Advances in Microbiology
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ACS Style

Zinia Jaman; Mohammad R. Karim; Korsi Dumenyo; Aminul H. Mirza. Antibacterial Activities of New Schiff Bases and Intermediate Silyl Compounds Synthesized from 5-Substituted-1,10-phenanthroline- 2,9-dialdehyde. Advances in Microbiology 2014, 04, 1140 -1153.

AMA Style

Zinia Jaman, Mohammad R. Karim, Korsi Dumenyo, Aminul H. Mirza. Antibacterial Activities of New Schiff Bases and Intermediate Silyl Compounds Synthesized from 5-Substituted-1,10-phenanthroline- 2,9-dialdehyde. Advances in Microbiology. 2014; 04 (15):1140-1153.

Chicago/Turabian Style

Zinia Jaman; Mohammad R. Karim; Korsi Dumenyo; Aminul H. Mirza. 2014. "Antibacterial Activities of New Schiff Bases and Intermediate Silyl Compounds Synthesized from 5-Substituted-1,10-phenanthroline- 2,9-dialdehyde." Advances in Microbiology 04, no. 15: 1140-1153.

Meeting report
Published: 01 November 2013 in Therapy
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Oxidative stress may be a key factor in the onset of certain diseases, including cancer. Oxy-radicals play important roles in the initiation, promotion, and progression of carcinogenesis. During the course of DNA excision and repair of oxidized, deaminated or alkylated bases apurinic/apyrimidinic (AP) or abasic sites are formed. The flavonoid quercetin was investigated for its ability to inhibit the oxidation of plasmid from Pectobacterium carotovorum KD 100 and Agrobacterium tumefaciens GV 3103 using the Fenton's chemistry. Utilizing a Colorimetric Assay Kit (Oxford Biomedical Research #FR09, Oxford, MI) for DNA damage quantification, AP sites were measured for plasmid following incubation with low doses of quercetin (1, 2, 2.5, 3, 3.5 µM) or without for 12 or 24 hr. With the increasing concentrations of quercetin the number of AP sites in each sample significantly decreased more for Pectobacterium carotovorum KD 100 compared to Agrobacterium tumefaciens GV 3103 in a time- and dose-dependent manner in comparison to their respective controls for the 12 and 24 hr incubation periods. The differences in decrease in AP sites can be linked to structural differences between the two bacterial strains and/or decreased oxidation for each sample with increased quercetin aliquots. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C60. Citation Format: William Y. Boadi, Damitea Johnson, Korsi Dumenyo. Exposure of low doses of quercetin on DNA oxidation in Pectobacterium carotovorum KD 100 and Agrobacterium tumefaciens GV 3103. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C60.

ACS Style

William Y. Boadi; Damitea Johnson; Korsi Dumenyo. Abstract C60: Exposure of low doses of quercetin on DNA oxidation inPectobacterium carotovorumKD 100 andAgrobacterium tumefaciensGV 3103. Therapy 2013, 12, 1 .

AMA Style

William Y. Boadi, Damitea Johnson, Korsi Dumenyo. Abstract C60: Exposure of low doses of quercetin on DNA oxidation inPectobacterium carotovorumKD 100 andAgrobacterium tumefaciensGV 3103. Therapy. 2013; 12 ():1.

Chicago/Turabian Style

William Y. Boadi; Damitea Johnson; Korsi Dumenyo. 2013. "Abstract C60: Exposure of low doses of quercetin on DNA oxidation inPectobacterium carotovorumKD 100 andAgrobacterium tumefaciensGV 3103." Therapy 12, no. : 1.

Journal article
Published: 01 September 2013 in Molecular Plant-Microbe Interactions®
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Exopolysaccharides (EPS) synthesized by plant-pathogenic bacteria are generally essential for virulence. The role of EPS produced by the vector-transmitted bacterium Xylella fastidiosa was investigated by knocking out two genes implicated in the EPS biosynthesis, gumD and gumH. Mutant strains were affected in growth characteristics in vitro, including adhesion to surfaces and biofilm formation. In addition, different assays were used to demonstrate that the mutant strains produced significantly less EPS compared with the wild type. Furthermore, gas chromatography–mass spectrometry showed that both mutant strains did not produce oligosaccharides. Biologically, the mutants were deficient in movement within plants, resulting in an avirulent phenotype. Additionally, mutant strains were affected in transmission by insects: they were very poorly transmitted by and retained within vectors. The gene expression profile indicated upregulation of genes implicated in cell-to-cell signaling and adhesins while downregulation in genes was required for within-plant movement in EPS-deficient strains. These results suggest an essential role for EPS in X. fastidiosa interactions with both plants and insects.

ACS Style

N. Killiny; Rufina Hernandez-Martinez; Korsi Dumenyo; D. A. Cooksey; Rodrigo Almeida. The Exopolysaccharide of Xylella fastidiosa Is Essential for Biofilm Formation, Plant Virulence, and Vector Transmission. Molecular Plant-Microbe Interactions® 2013, 26, 1044 -1053.

AMA Style

N. Killiny, Rufina Hernandez-Martinez, Korsi Dumenyo, D. A. Cooksey, Rodrigo Almeida. The Exopolysaccharide of Xylella fastidiosa Is Essential for Biofilm Formation, Plant Virulence, and Vector Transmission. Molecular Plant-Microbe Interactions®. 2013; 26 (9):1044-1053.

Chicago/Turabian Style

N. Killiny; Rufina Hernandez-Martinez; Korsi Dumenyo; D. A. Cooksey; Rodrigo Almeida. 2013. "The Exopolysaccharide of Xylella fastidiosa Is Essential for Biofilm Formation, Plant Virulence, and Vector Transmission." Molecular Plant-Microbe Interactions® 26, no. 9: 1044-1053.

Corrigendum
Published: 28 February 2012 in Molecular Plant Pathology
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ACS Style

Caleb M. Kersey; Paul A. Agyemang; C. Korsi Dumenyo. CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum. Molecular Plant Pathology 2012, 13, 327 -327.

AMA Style

Caleb M. Kersey, Paul A. Agyemang, C. Korsi Dumenyo. CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum. Molecular Plant Pathology. 2012; 13 (3):327-327.

Chicago/Turabian Style

Caleb M. Kersey; Paul A. Agyemang; C. Korsi Dumenyo. 2012. "CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum." Molecular Plant Pathology 13, no. 3: 327-327.

Journal article
Published: 01 June 2011 in Molecular Plant Pathology
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Pectobacterium carotovorum (formerly Erwinia carotovora ssp. carotovora) is a phytopathogenic bacterium that causes soft rot disease, characterized by water‐soaked soft decay, resulting from the action of cell wall‐degrading exoenzymes secreted by the pathogen. Virulence in soft rot bacteria is regulated by environmental factors, host and bacterial chemical signals, and a network of global and gene‐specific bacterial regulators. We isolated a mini‐Tn5 mutant of P. carotovorum that is reduced in the production of extracellular pectate lyase, protease, polygalacturonase and cellulase. The mutant is also decreased in virulence as it macerates less host tissues than its parent and is severely impaired in multiplication in planta. The inactivated gene responsible for the reduced virulent phenotype was identified as corA. CorA, a magnesium/nickel/cobalt membrane transporter, is the primary magnesium transporter for many bacteria. Compared with the parent, the CorA‐ mutant is cobalt resistant. The mutant phenotype was confirmed in parental strain P. carotovorum by marker exchange inactivation of corA. A functional corA+ DNA from P. carotovorum restored exoenzyme production and pathogenicity to the mutants. The P. carotovorum corA+ clone also restored motility and cobalt sensitivity to a CorA‐ mutant of Salmonella enterica. These data indicate that CorA is required for exoenzyme production and virulence in P. carotovorum.

ACS Style

Caleb M. Kersey; Paul A. Agyemang; C. Korsi Dumenyo. CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum. Molecular Plant Pathology 2011, 13, 58 -71.

AMA Style

Caleb M. Kersey, Paul A. Agyemang, C. Korsi Dumenyo. CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum. Molecular Plant Pathology. 2011; 13 (1):58-71.

Chicago/Turabian Style

Caleb M. Kersey; Paul A. Agyemang; C. Korsi Dumenyo. 2011. "CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum." Molecular Plant Pathology 13, no. 1: 58-71.

Journal article
Published: 15 April 2009 in Applied and Environmental Microbiology
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The xylem-limited, insect-transmitted bacterium Xylella fastidiosa causes Pierce's disease in grapes through cell aggregation and vascular clogging. GacA controls various physiological processes and pathogenicity factors in many gram-negative bacteria, including biofilm formation in Pseudomonas syringae pv. tomato DC3000. Cloned gacA of X. fastidiosa was found to restore the hypersensitive response and pathogenicity in gacA mutants of P. syringae pv. tomato DC3000 and Erwinia amylovora . A gacA mutant of X. fastidiosa (DAC1984) had significantly reduced abilities to adhere to a glass surface, form biofilm, and incite disease symptoms on grapevines, compared with the parent (A05). cDNA microarray analysis identified 7 genes that were positively regulated by GacA, including xadA and hsf , predicted to encode outer membrane adhesion proteins, and 20 negatively regulated genes, including gumC and an antibacterial polypeptide toxin gene, cvaC . These results suggest that GacA of X. fastidiosa regulates many factors, which contribute to attachment and biofilm formation, as well as some physiological processes that may enhance the adaptation and tolerance of X. fastidiosa to environmental stresses and the competition within the host xylem.

ACS Style

Xiang Yang Shi; C. Korsi Dumenyo; Rufina Hernandez-Martinez; Hamid Azad; Donald A. Cooksey. Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by gacA. Applied and Environmental Microbiology 2009, 75, 2275 -2283.

AMA Style

Xiang Yang Shi, C. Korsi Dumenyo, Rufina Hernandez-Martinez, Hamid Azad, Donald A. Cooksey. Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by gacA. Applied and Environmental Microbiology. 2009; 75 (8):2275-2283.

Chicago/Turabian Style

Xiang Yang Shi; C. Korsi Dumenyo; Rufina Hernandez-Martinez; Hamid Azad; Donald A. Cooksey. 2009. "Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by gacA." Applied and Environmental Microbiology 75, no. 8: 2275-2283.

Journal article
Published: 01 November 2007 in Applied and Environmental Microbiology
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Many virulence genes in plant bacterial pathogens are coordinately regulated by “global” regulatory genes. Conducting DNA microarray analysis of bacterial mutants of such genes, compared with the wild type, can help to refine the list of genes that may contribute to virulence in bacterial pathogens. The regulatory gene algU , with roles in stress response and regulation of the biosynthesis of the exopolysaccharide alginate in Pseudomonas aeruginosa and many other bacteria, has been extensively studied. The role of algU in Xylella fastidiosa , the cause of Pierce's disease of grapevines, was analyzed by mutation and whole-genome microarray analysis to define its involvement in aggregation, biofilm formation, and virulence. In this study, an algU :: nptII mutant had reduced cell-cell aggregation, attachment, and biofilm formation and lower virulence in grapevines. Microarray analysis showed that 42 genes had significantly lower expression in the algU :: nptII mutant than in the wild type. Among these are several genes that could contribute to cell aggregation and biofilm formation, as well as other physiological processes such as virulence, competition, and survival.

ACS Style

Xiang Yang Shi; C. Korsi Dumenyo; Rufina Hernandez-Martinez; Hamid Azad; Donald A. Cooksey. Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by algU. Applied and Environmental Microbiology 2007, 73, 6748 -6756.

AMA Style

Xiang Yang Shi, C. Korsi Dumenyo, Rufina Hernandez-Martinez, Hamid Azad, Donald A. Cooksey. Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by algU. Applied and Environmental Microbiology. 2007; 73 (21):6748-6756.

Chicago/Turabian Style

Xiang Yang Shi; C. Korsi Dumenyo; Rufina Hernandez-Martinez; Hamid Azad; Donald A. Cooksey. 2007. "Characterization of Regulatory Pathways in Xylella fastidiosa : Genes and Phenotypes Controlled by algU." Applied and Environmental Microbiology 73, no. 21: 6748-6756.

Journal article
Published: 25 January 2007 in Journal of Chemical Ecology
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In the Temecula Valley of California the proximity of citrus groves to vineyards influences the incidence and severity of Pierce’s disease (PD) in grapes, a disease caused by the gram-negative bacterium, Xylella fastidiosa. Although the glassy-winged sharpshooter (GWSS), the major insect vector of the bacterium, feeds on and moves back and forth between citrus groves and vineyards, there are no visible symptoms of disease caused by X. fastidiosa in citrus. Previous evidences suggested that while grapevines are susceptible to the PD strain of X. fastidiosa, citrus trees are resistant or tolerant but could be a reservoir to harbor the pathogen for the GWSS acquisition. We investigated the mechanisms of host plant resistance/susceptibility by examining the in vitro effect of xylem fluid from grapefruit, orange, lemon, and grape on the growth, aggregation, and attachment of a X. fastidiosa strain isolated from grape. Our results revealed that xylem fluid from grapefruit, orange, and lemon trees caused the bacterial cells to form aggregations of large whitish clumps, whereas the xylem fluid from grape vines created a visible thick biofilm. The densities of X. fastidiosa cells in grapefruit xylem fluid treatment were significantly higher at 6, 8, and 9 d postinoculation compared with those in grape xylem fluid treatment. The cell densities of X. fastidiosa cultures in orange or lemon xylem fluid were generally lower than those in grape xylem fluid treatment, whereas citrus xylem fluid significantly inhibited X. fastidiosa biofilm formation compared to grape xylem fluid.

ACS Style

J. L. Bi; C. K. Dumenyo; Rufina Hernandez-Martinez; D. A. Cooksey; N. C. Toscano. Effect of Host Plant Xylem Fluid on Growth, Aggregation, and Attachment of Xylella fastidiosa. Journal of Chemical Ecology 2007, 33, 493 -500.

AMA Style

J. L. Bi, C. K. Dumenyo, Rufina Hernandez-Martinez, D. A. Cooksey, N. C. Toscano. Effect of Host Plant Xylem Fluid on Growth, Aggregation, and Attachment of Xylella fastidiosa. Journal of Chemical Ecology. 2007; 33 (3):493-500.

Chicago/Turabian Style

J. L. Bi; C. K. Dumenyo; Rufina Hernandez-Martinez; D. A. Cooksey; N. C. Toscano. 2007. "Effect of Host Plant Xylem Fluid on Growth, Aggregation, and Attachment of Xylella fastidiosa." Journal of Chemical Ecology 33, no. 3: 493-500.

Journal article
Published: 01 November 2006 in Plant Disease
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Xylella fastidiosa is a xylem-limited, nutritionally fastidious bacterium that causes several plant diseases including Pierce's disease (PD) in grape and leaf scorch in almond (ALS) and oleander (OLS). OLS strains belong to X. fastidiosa subsp. sandyi, PD strains belong to X. fastidiosa subsp. fastidiosa, and strains from almond designated as ALS strains are of two general types belonging either to X. fastidiosa subsp. multiplex or X. fastidiosa subsp. fastidiosa. The ALS strains assigned to X. fastidiosa subsp. multiplex belong to two different genotypes (ALSI and ALSII) below the subspecies level. The OLS strains do not infect grape or almond. PD strains produce diseases in grape, alfalfa, almond, and some weeds, but they do not infect oleander, oak, peach, or citrus. ALS strains that belong to X. fastidiosa subsp. multiplex do not produce disease on grape. In this study, a relatively simple polymerase chain reaction (PCR) based method was developed to distinguish among PD, OLS, and ALS strains. PCR performed with primers XF1968-L and XF1968-R amplified a 638-bp fragment from OLS strains but not from PD strains or ALS strains that belong to X. fastidiosa subsp. fastidiosa. PCR with primers XF2542-L and XF2542-R amplified a 412-bp fragment from PD strains, but not from OLS strains. PCR with primers ALM1 and ALM2 produced a fragment of 521 bp from strains isolated from almond that belong to X. fastidiosa subsp. multiplex. The combination of the three primer sets allowed the distinction of the two ALS genotypes of X. fastidiosa subsp. multiplex. These results are in agreement with those obtained from analysis of sequences of 16S-23S rDNA intergenic spacer regions sequence analysis and with previous results based on randomly amplified polymorphic DNA analysis.

ACS Style

Rufina Hernandez-Martinez; H. S. Costa; Korsi Dumenyo; D. A. Cooksey. Differentiation of Strains of Xylella fastidiosa Infecting Grape, Almonds, and Oleander Using a Multiprimer PCR Assay. Plant Disease 2006, 90, 1382 -1388.

AMA Style

Rufina Hernandez-Martinez, H. S. Costa, Korsi Dumenyo, D. A. Cooksey. Differentiation of Strains of Xylella fastidiosa Infecting Grape, Almonds, and Oleander Using a Multiprimer PCR Assay. Plant Disease. 2006; 90 (11):1382-1388.

Chicago/Turabian Style

Rufina Hernandez-Martinez; H. S. Costa; Korsi Dumenyo; D. A. Cooksey. 2006. "Differentiation of Strains of Xylella fastidiosa Infecting Grape, Almonds, and Oleander Using a Multiprimer PCR Assay." Plant Disease 90, no. 11: 1382-1388.

Journal article
Published: 06 August 2003 in Molecular Plant Pathology
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This is the first report of a genotypic analysis of the phytopathogenic bacteria Xylella fastidiosa (Xf) using differences within intra‐ and intergenic regions of pathogenic genes. Orthologous sequences from the genome of Xf were identified for genes involved in the regulation of pathogenicity factors (rpf) from Xanthomonas campestris pv. campestris (Xcc). While the rpf genes were conserved, the chromosomal region revealed differences in gene sizes and intergenic spacings and a major translocational event when compared to Xcc. Primers were designed to amplify three regions: the intragenic region of rpfA (2354 bp), the intergenic region between rpfA and rpfB (5772 bp), and the intergenic region between rpfC and rpfF (2314 bp). Amplicons were obtained for all three regions from 32 of the 33 Xf isolates tested from citrus, grape, coffee, plum, hibiscus and periwinkle. Three Xcc isolates from cruciferous plants only generated PCR products for the rpfC‐F region. Cleaved amplified polymorphic sequences (CAPS) (TaqαI) revealed differential banding profiles for the rpfA‐B and rpfC‐F regions. Xylella isolates were separated into seven groups via rpfA‐B, of which five contained only citrus, while the other two had citrus, grape and coffee, and citrus, coffee, plum and hibiscus isolates. rpfC‐F separated the isolates into three host‐related groups. Citrus, coffee and hibiscus isolates formed one group, while the other two groups were comprised solely of grape and plum isolates. Xcc isolates formed an out‐group. In silico analysis supports these results, which reveal the potential of the rpf genes for genotypic analysis of Xylella fastidiosa.

ACS Style

Lyndel W. Meinhardt; Milena P. M. A. Ribeiro; Helvecio Coletta-Filho; Korsi Dumenyo; Sui M. Tsai; Cláudia De M. Bellato; Cláudia De M. Bellato. Genotypic analysis of Xylella fastidiosa isolates from different hosts using sequences homologous to the Xanthomonas rpf genes. Molecular Plant Pathology 2003, 4, 327 -335.

AMA Style

Lyndel W. Meinhardt, Milena P. M. A. Ribeiro, Helvecio Coletta-Filho, Korsi Dumenyo, Sui M. Tsai, Cláudia De M. Bellato, Cláudia De M. Bellato. Genotypic analysis of Xylella fastidiosa isolates from different hosts using sequences homologous to the Xanthomonas rpf genes. Molecular Plant Pathology. 2003; 4 (5):327-335.

Chicago/Turabian Style

Lyndel W. Meinhardt; Milena P. M. A. Ribeiro; Helvecio Coletta-Filho; Korsi Dumenyo; Sui M. Tsai; Cláudia De M. Bellato; Cláudia De M. Bellato. 2003. "Genotypic analysis of Xylella fastidiosa isolates from different hosts using sequences homologous to the Xanthomonas rpf genes." Molecular Plant Pathology 4, no. 5: 327-335.

Journal article
Published: 15 March 2001 in Journal of Bacteriology
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RsmB Ecc specifies a nontranslatable RNA regulator that controls exoprotein production and pathogenicity in soft rot-causing Erwinia carotovora subsp. carotovora . This effect of rsmB Ecc RNA is mediated mostly by neutralizing the function of RsmA Ecc , an RNA-binding protein of E. carotovora subsp. carotovora , which acts as a global negative regulator. To determine the occurrence of functional homologs of rsmB Ecc in non-soft-rot-causing Erwinia species, we cloned the rsmB genes of E. amylovora ( rsmB Ea ) and E. herbicola pv. gypsophilae ( rsmB Ehg ). We show that rsmB Ea in E. amylovora positively regulates extracellular polysaccharide (EPS) production, motility, and pathogenicity. In E. herbicola pv. gypsophilae, rsmB Ehg elevates the levels of transcripts of a cytokinin ( etz ) gene and stimulates the production of EPS and yellow pigment as well as motility. RsmA Ea and RsmA Ehg have more than 93% identity to RsmA Ecc and, like the latter, function as negative regulators by affecting the transcript stability of the target gene. The rsmB genes reverse the negative effects of RsmA Ea , RsmA Ehg , and RsmA Ecc , but the extent of reversal is highest with homologous combinations of rsm genes. These observations and findings that rsmB Ea and rsmB Ehg RNA bind RsmA Ecc indicate that the rsmB effect is channeled via RsmA. Additional support for this conclusion comes from the observation that the rsmB genes are much more effective as positive regulators in a RsmA + strain of E. carotovora subsp. carotovora than in its RsmA − derivative. E. herbicola pv. gypsophilae produces a 290-base rsmB transcript that is not subject to processing. By contrast, E. amylovora produces 430- and 300-base rsmB transcripts, the latter presumably derived by processing of the primary transcript as previously noted with the transcripts of rsmB Ecc . Southern blot hybridizations revealed the presence of rsmB homologs in E. carotovora, E. chrysanthemi, E. amylovora, E. herbicola, E. stewartii and E. rhapontici , as well as in other enterobacteria such as Escherichia coli, Salmonella enterica serovar Typhimurium, Serratia marcescens, Shigella flexneri, Enterobacter aerogenes, Klebsiella pneumoniae, Yersinia enterocolitica , and Y. pseudotuberculosis . A comparison of rsmB sequences from several of these enterobacterial species revealed a highly conserved 34-mer region which is predicted to play a role in positive regulation by rsmB RNA.

ACS Style

Weilei Ma; Yaya Cui; Yang Liu; C. Korsi Dumenyo; Asita Mukherjee; Arun K. Chatterjee. Molecular Characterization of Global Regulatory RNA Species That Control Pathogenicity Factors in Erwinia amylovora and Erwinia herbicola pv. gypsophilae. Journal of Bacteriology 2001, 183, 1870 -1880.

AMA Style

Weilei Ma, Yaya Cui, Yang Liu, C. Korsi Dumenyo, Asita Mukherjee, Arun K. Chatterjee. Molecular Characterization of Global Regulatory RNA Species That Control Pathogenicity Factors in Erwinia amylovora and Erwinia herbicola pv. gypsophilae. Journal of Bacteriology. 2001; 183 (6):1870-1880.

Chicago/Turabian Style

Weilei Ma; Yaya Cui; Yang Liu; C. Korsi Dumenyo; Asita Mukherjee; Arun K. Chatterjee. 2001. "Molecular Characterization of Global Regulatory RNA Species That Control Pathogenicity Factors in Erwinia amylovora and Erwinia herbicola pv. gypsophilae." Journal of Bacteriology 183, no. 6: 1870-1880.