Molecular Genetic Characterization of a Pathogenicity-attenuated Mutant of Pseudomonas Syringae Pathovar Syringae PDF Download
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Author: Yuqi Zhao
Publisher:
ISBN:
Category : Molecular genetics
Languages : en
Pages : 434
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Book Description
A pathogenicity locus of Pseudomonas syringae pv. syringae identified by Tn5 mutagenesis was investigated. The mutant strain PS9024 is attenuated for disease expression in its host, Phaseolus vulgaris, but produces the hypersensitive reaction (HR) in the nonhost, tobacco (Nicotina tabacum). A cosmid clone carrying 16 kilobases (kb) of contiguous genomic DNA partially complements this mutant. Altered growth of the mutant in planta was also partially restored. Marker exchange mutagenesis with Tn3- HoHo1 at two other sites within this locus results in mutants with attenuated and severely reduced pathogenicity. The locus is complex and contains repetitive DNA sequences. Northern analysis reveals that this locus is expressed in planta, but is not expressed in a rich growth medium, and the transcript is larger than 10 kb, suggesting that the locus is transcribed as a polycistronic mRNA. Comparison of total cellular protein profiles of R32 and PS9024 using SDS-PAGE analysis further reveals that at least nine protein bands ranging from approximately 100 kD or above in size are present in the wild type strain R32, but absent from the mutant. Additionally, a protein of approximately 45 kD is absent from the mutant. The site of Tn5 insertion has been partially sequenced. The initial search of the data banks suggested a gene or genes related to the ornithine biosynthetic pathway map to this locus. Further study strongly suggest a gene that encodes a membranceassociated protein and under the control of a promoter identical to appA gene promoter maps at this site and it is involved in the process of pathogenesis.
Author: Yuqi Zhao
Publisher:
ISBN:
Category : Molecular genetics
Languages : en
Pages : 434
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Book Description
A pathogenicity locus of Pseudomonas syringae pv. syringae identified by Tn5 mutagenesis was investigated. The mutant strain PS9024 is attenuated for disease expression in its host, Phaseolus vulgaris, but produces the hypersensitive reaction (HR) in the nonhost, tobacco (Nicotina tabacum). A cosmid clone carrying 16 kilobases (kb) of contiguous genomic DNA partially complements this mutant. Altered growth of the mutant in planta was also partially restored. Marker exchange mutagenesis with Tn3- HoHo1 at two other sites within this locus results in mutants with attenuated and severely reduced pathogenicity. The locus is complex and contains repetitive DNA sequences. Northern analysis reveals that this locus is expressed in planta, but is not expressed in a rich growth medium, and the transcript is larger than 10 kb, suggesting that the locus is transcribed as a polycistronic mRNA. Comparison of total cellular protein profiles of R32 and PS9024 using SDS-PAGE analysis further reveals that at least nine protein bands ranging from approximately 100 kD or above in size are present in the wild type strain R32, but absent from the mutant. Additionally, a protein of approximately 45 kD is absent from the mutant. The site of Tn5 insertion has been partially sequenced. The initial search of the data banks suggested a gene or genes related to the ornithine biosynthetic pathway map to this locus. Further study strongly suggest a gene that encodes a membranceassociated protein and under the control of a promoter identical to appA gene promoter maps at this site and it is involved in the process of pathogenesis.
Author: K. Rudolph
Publisher: Springer Science & Business Media
ISBN: 9401154724
Category : Science
Languages : en
Pages : 687
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Book Description
During the last decade, research on Pseudomonas syringae pathovars and related pathogens has progressed rapidly, opening up many new avenues. The application of molecular genetics has provided new insights into determinants of pathogenicity and virulence. Progress has also been made in elucidating the chemical structures and modes of action of phytotoxins from Pseudomonas syringae; by establishing novel strategies for disease control; in biotechnological applications; by studying the resistant reaction of the plant with a combined biochemical and genetic approach; and in the development of new detection and identification methodologies as tools in epidemiological studies. With such rapid advances it becomes more and more difficult to keep abreast of the developments and concepts within disciplines, all involving research on pathovars of P. syringae. In an attempt to provide a balanced overview, recent developments in these rapidly expanding fields have been critically reviewed at the beginning of each chapter by internationally renowned experts. Our comprehensive coverage has been made possible because all the contributors to this volume presented their latest findings at the `5th International Conference on Pseudomonas syringae Pathovars and Related Pathogens' in Berlin, September 3-8, 1995. In this way, it was possible to bring together contributions from a wide range of fields including phytopathology, genetics, bacteriology, plant breeding, plant protection, and taxonomy. This book is not intended simply as a record of the proceedings of the Berlin Conference, but as an extension of recent findings and hypotheses put forward at the meeting. All papers published in this volume have been reviewed by the Editors.
Author: Gregory Bertoni
Publisher:
ISBN:
Category : Beans
Languages : en
Pages : 238
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Book Description
The in planta growth of three wild type strains of phytopathogenic bacteria and three nonpathogenic mutant strains was studied to determine if mutations eliminating the ability of the mutant strains to cause disease had affected their growth in leaf tissue. The mutant strains were obtained by Tn5 mutagenesis of Pseudomonas svringae pv. phaseolicola strain PP7010 and P. svringae pv. svringae strain PS9020, organisms which respectively cause halo blight of bean and bacterial brown spot of bean. Through cloning of Tn5-containing genomic DNA, bacterial conjugation, auxanography, and genetic marker exchange experiments, these studies demonstrated that the Tn5 mutation in strain PP7014 of P. svringae pv. phaseolicola had created an auxotrophic requirement for uracil and had caused an inability to produce typical necrotic and chlorotic disease symptoms in bean leaves. A simple and reproducible bioassay was developed to monitor bacterial growth in leaf tissue. Using this bioassay, mutant PP7014 was shown to be incapable of growth in planta, presumably due to its inability to obtain uracil for growth in the leaf. However, a similar Tn5 arginine auxotroph, PP7510, was capable of multiplication in bean leaves, demonstrating that prototrophy of P. svringae pv. phaseolicola is not a prerequisite for pathogenicity. Growth studies with pathogenic wild type P. syringae pv. syringae strains J900 and PS9020 revealed a correlation between growth in planta and the severity of symptom expression. Altered growth patterns and symptom expression were shown for two nonpathogenic strains derived by Tn5. mutagenesis of PS9020. Mutant strain PS9021 was incapable of in planta growth and disease symptom expression. Mutant strain PS9024, although initially capable of rapid multiplication in bean leaves, was unable to maintain the high population levels and produce the characteristic symptoms of the parental wild type strain. Further growth studies were conducted to investigate the complementation of the Tn5 mutation in PS9021 by cosmids containing wild type PS9020 DNA homologous to the mutated region. Although stable throughout multiple rounds of bacterial replication, the cosmids could partially, but not completely, restore the wild type in planta growth and symptom expression pattern to PS9021.
Author: Suresh S. Patil
Publisher: Springer
ISBN: 1461230845
Category : Technology & Engineering
Languages : en
Pages : 271
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Book Description
The field of the molecular basis of plant disease is rapidly developing. The nineteen chapters of current information in Molecular Strategies of Pathogens and Host Plants are written by well known experts in the United States and Japan, and cover recent progress in the genetics and molecular biology of bacteria and fungi which are pathogens of plants. This research emphasizes the genes which are responsible for production of toxins, enzymes, and hormones that lead to pathogenicity and specificity in plant-pathogen interactions. Several chapters also examine the biochemistry of the plant's response to microbial attack.
Author: Sruti Bandyopadhyay
Publisher:
ISBN:
Category : Plant-pathogen relationships
Languages : en
Pages : 396
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Author: Julie Zwiesler-Vollick
Publisher:
ISBN:
Category : Arabidopsis thaliana
Languages : en
Pages : 412
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Author: Carlos Arredondo Rodriguez
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Author:
Publisher:
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Category :
Languages : en
Pages :
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Author: Amber Lorge
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Gene regulation in bacteria is highly complex and requires the activity of sigma factors that function as transcriptional regulators. In Pseudomonas syringae pv. syringae B728a, 14 sigma factors have been identified. One of the more interesting is rpoN, encoding Sigma 54, which was initially described for its role in nitrogen utilization and later shown to be involved in regulating adhesion, motility, toxin production, and pathogenicity. The only commonality identified amongst these genes is that gene regulation by Sigma 54 is not essential for normal growth and development because mutational inactivation of rpoN is not lethal. Unlike Sigma 70, which recognizes promoter sites located at positions -10/-35 upstream of the transcription initiation site, Sigma 54 recognizes sites located at positions -12/-24. P.s. pv. syringae B728a encodes an RpoN that shares 80-98% identity with other Pseudomonas species. Promoter scans were conducted on the B728a genome to look for probable binding sites of RpoN. Analysis revealed that RpoN may be involved in regulating genes encoding ABC transporters, drug efflux pumps, flagella proteins, nitrate transporters, and several regulatory proteins. An insertional mutation in the rpoN gene was constructed in the B728a genome and a phenotypic analysis was initiated. Decreased swarming and adhesion ability of the rpoN mutant was observed as compared to B728a. The ability to utilize sole nitrogen sources was also affected. The rpoN mutant showed little or no growth on sole nitrogen sources such as alanine, histidine, lysine, and serine. Pathogenicity was shown to require a functional RpoN, as both HR and disease development was effected by an rpoN mutation. Pseudomonas syringae pv. syringae is most known for the production of two phytotoxins. Unlike RpoN in other species, in P.s. pv. syringae B728a it appears to indirectly down regulate toxin production of syringomycin and syringopeptin. The goal of this study was to characterize some of the important roles RpoN is known to possess and to understand its role in the plant pathogenic and epiphytic lifestyle of P. s. pv. syringae B728a.
Author: Nicola Sante Iacobellis
Publisher: Springer Science & Business Media
ISBN: 9401701334
Category : Science
Languages : en
Pages : 673
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Book Description
This volume mainly reports on new and recent advancements on different aspects of Pseudomonas syringae, a plant pathogenic bacterial species that include a high number of pathogens of important crops, which is an interesting model organism in plant pathology. In addition some related fluorescent Pseudomonas spp., responsible of new and emerging diseases, as well as some pathogens previously included in the above genus and now classified in the genera Ralstonia, Acidovorax are also considered. The tremendous recent advancements on: the ecology and epidemiology and, in particular, the adaptation of P. syringae to stresses and adverse environmental conditions; the function and regulation of genes involved in the production of phytotoxins and on their mechanism of action in the interaction with the host cells; the structure, function and regulation of type three secretion system (TTSS) and the transport of the effectors proteins in the host cells; the possibility to control diseases through the induction of the systemic acquired resistance (SAR); the development of molecular techniques for the highly specific and sensible identification and detection of pathogens; the determination of the causal agents of new and emerging diseases as well the classification of the different pathovars of P. syringae; are reported in 76 chapters cured by leading scientist in the respective fields.
