Project description:Agrobacterium tumefaciens, a bacterial species found in temperate soils world wide, is the causative agent of crown gall disease on many plants. A. tumefaciens-induced tumours are feared in orchards and vineyards because of their pathological interference with nutrient and water supply which results in crop decline. Small wounds at the crown of the plant, usually induced by wind-bending, are potential entry sites for the bacterium. The tumorous growth is initiated by the integration and expression of the T-DNA of the bacterial Ti plasmid within the plant nuclear DNA. The T-DNA encodes enzymes catalysing the synthesis of increased concentrations of auxin and cytokinin, and of opines which stimulate cell division and enlargement. The fast growing tumours have been shown to be a strong nutrient sink on their host plants. As a matter of fact, sugar and K+ content were found to be up to 10- and 5-fold, respectively, higher in this tissue and transpiration was about 15 times increased compared to normal tissue. Whereas the morphological structure as well as some physiological and biochemical parameters of the tumour have been analysed in detail, little is known about the underlying gene expression pattern. Proliferation and growth of the tumour induced by Agrobacterium tumefaciens is obviously due to the extraordinary high concentration of phytohormons, minerals and metabolites. Their influence on regulation of gene transcription will provide information on the mechanisms underlying fast tumour growth. In a project funded by the DFG we recently started to investigate the role of solute transporter for tumour development on the model plant Arabidopsis thaliana. By comparing the expression pattern of RNA preparations from Arabidopsis tumour and non-tumour tissue, we will be able to identify genes which facilitate crown gall development. For the expression analysis with an Affymetrix full genome chip we will induce tumours at the base of an injured Arabidopsis inflorescence stalk (var. Wassilewskija, WS-2). RNA will be extraxted from tumour and injured non-tumor inflorescence stalk tissue using the RNeasy Plant Mini Kit (Qiagen), followed by a DNase treatment to eliminate DNA contamination. This Series record represents a partial dataset. The complete dataset was submitted under GEO accession number GSE13927. Experimenter name = Rosalia Deeken Experimenter phone = +49 931 8886121 Experimenter fax = +49 931 8886158 Experimenter institute = Julius-von-Sachs-Institute of Biosciences Molecular Plant Physiology and Electrophysiology Experimenter address = Julius-von-Sachs-Platz 2 Experimenter address = Wuerzburg Experimenter zip/postal_code = D-97082 Experimenter country = Germany Keywords: pathogenicity_design
Project description:Agrobacterium tumefaciens, a bacterial species found in temperate soils world wide, is the causative agent of crown gall disease on many plants. A. tumefaciens-induced tumours are feared in orchards and vineyards because of their pathological interference with nutrient and water supply which results in crop decline. Small wounds at the crown of the plant, usually induced by wind-bending, are potential entry sites for the bacterium. The tumorous growth is initiated by the integration and expression of the T-DNA of the bacterial Ti plasmid within the plant nuclear DNA. The T-DNA encodes enzymes catalysing the synthesis of increased concentrations of auxin and cytokinin, and of opines which stimulate cell division and enlargement. The fast growing tumours have been shown to be a strong nutrient sink on their host plants. As a matter of fact, sugar and K+ content were found to be up to 10- and 5-fold, respectively, higher in this tissue and transpiration was about 15 times increased compared to normal tissue. Whereas the morphological structure as well as some physiological and biochemical parameters of the tumour have been analysed in detail, little is known about the underlying gene expression pattern. Proliferation and growth of the tumour induced by Agrobacterium tumefaciens is obviously due to the extraordinary high concentration of phytohormons, minerals and metabolites. Their influence on regulation of gene transcription will provide information on the mechanisms underlying fast tumour growth. In a project funded by the DFG we recently started to investigate the role of solute transporter for tumour development on the model plant Arabidopsis thaliana. By comparing the expression pattern of RNA preparations from Arabidopsis tumour and non-tumour tissue, we will be able to identify genes which facilitate crown gall development. For the expression analysis with an Affymetrix full genome chip we will induce tumours at the base of an injured Arabidopsis inflorescence stalk (var. Wassilewskija, WS-2). RNA will be extraxted from tumour and injured non-tumor inflorescence stalk tissue using the RNeasy Plant Mini Kit (Qiagen), followed by a DNase treatment to eliminate DNA contamination. Experimenter name = Rosalia Deeken; Experimenter phone = +49 931 8886121; Experimenter fax = +49 931 8886158; Experimenter institute = Julius-von-Sachs-Institute of Biosciences Molecular Plant Physiology and Electrophysiology; Experimenter address = Julius-von-Sachs-Platz 2; Experimenter address = Wuerzburg; Experimenter zip/postal_code = D-97082; Experimenter country = Germany Experiment Overall Design: 4 samples were used in this experiment
Project description:Agrobacterium tumefaciens, a bacterial species found in temperate soils world wide, is the causative agent of crown gall disease on many plants. A. tumefaciens-induced tumours are feared in orchards and vineyards because of their pathological interference with nutrient and water supply which results in crop decline. Small wounds at the crown of the plant, usually induced by wind-bending, are potential entry sites for the bacterium. The tumorous growth is initiated by the integration and expression of the T-DNA of the bacterial Ti plasmid within the plant nuclear DNA. The T-DNA encodes enzymes catalysing the synthesis of increased concentrations of auxin and cytokinin, and of opines which stimulate cell division and enlargement. The fast growing tumours have been shown to be a strong nutrient sink on their host plants. As a matter of fact, sugar and K+ content were found to be up to 10- and 5-fold, respectively, higher in this tissue and transpiration was about 15 times increased compared to normal tissue. Whereas the morphological structure as well as some physiological and biochemical parameters of the tumour have been analysed in detail, little is known about the underlying gene expression pattern. Proliferation and growth of the tumour induced by Agrobacterium tumefaciens is obviously due to the extraordinary high concentration of phytohormons, minerals and metabolites. Their influence on regulation of gene transcription will provide information on the mechanisms underlying fast tumour growth. In a project funded by the DFG we recently started to investigate the role of solute transporter for tumour development on the model plant Arabidopsis thaliana. By comparing the expression pattern of RNA preparations from Arabidopsis tumour and non-tumour tissue, we will be able to identify genes which facilitate crown gall development. For the expression analysis with an Affymetrix full genome chip we will induce tumours at the base of an injured Arabidopsis inflorescence stalk (var. Wassilewskija, WS-2). RNA will be extraxted from tumour and injured non-tumor inflorescence stalk tissue using the RNeasy Plant Mini Kit (Qiagen), followed by a DNase treatment to eliminate DNA contamination.
Project description:This study describes physiological changes, morphological adaptations and the regulation of pathogen defense responses in Arabidopsis crown galls. Crown gall development was induced on intact plants under most natural conditions with Agrobacterium tumefaciens. Differential gene expression and the metabolite pattern was determined by comparing crown galls with mock-inoculated inflorescence stalk segments of the same age.
Project description:Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues and, subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role this regulator plays on gene expression.
Project description:Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues and, subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role this regulator plays on gene expression. Four biological replicates, Independent RNA preparations, Two dye-swaps
Project description:Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues and, subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role this regulator plays on gene expression.
Project description:The intention of these gene expression analysis was to study host responses to an infection with Agrobacterium tumefaciens at different stages of crown gall development. Therefore the transcriptome of infected inflorescence stalk tissue and mature crown galls of Arabidopsis thaliana (WS-2) was determined of three different time points. These were compared with the transcriptome of mock-infected inflorescence stalk tissue (reference) of the same age. The following time points were analyzed: (i) three hours post inoculation, before the T-DNA is integrated into the host genome (ii) six days after inoculation when the T-DNA is present in the nucleus and the oncogenes are expressed in the host cell, and (iii) 35 days after inoculation when a mature tumors has developed. For the three-hour- (3hpi) and six-day- time point (6dpi) plants were infected with the virulent strain C58, harboring a T-DNA, or with strain GV3101, containing a disarmed Ti-plasmid. This allows discrimination between signals which derive from the bacterial pathogen and the T-DNA encoded oncogenes. This SuperSeries is composed of the SubSeries listed below.
Project description:The intention of these gene expression analysis was to study host responses to an infection with Agrobacterium tumefaciens at different stages of crown gall development. Therefore the transcriptome of infected inflorescence stalk tissue and mature crown galls of Arabidopsis thaliana (WS-2) was determined of three different time points. These were compared with the transcriptome of mock-infected inflorescence stalk tissue (reference) of the same age. The following time points were analyzed: (i) three hours post inoculation, before the T-DNA is integrated into the host genome (ii) six days after inoculation when the T-DNA is present in the nucleus and the oncogenes are expressed in the host cell, and (iii) 35 days after inoculation when a mature tumors has developed. For the three-hour- (3hpi) and six-day- time point (6dpi) plants were infected with the virulent strain C58, harboring a T-DNA, or with strain GV3101, containing a disarmed Ti-plasmid. This allows discrimination between signals which derive from the bacterial pathogen and the T-DNA encoded oncogenes. This SuperSeries is composed of the following subset Series:; GSE13929: Arabidopsis thaliana three hours after infection with Agrobacterium tumefaciens; GSE13930: Arabidopsis thaliana six days after infection with Agrobacterium tumefaciens; GSE13927: Transcriptome of mature A. thaliana crown galls. Experiment Overall Design: Refer to individual Series