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Current Protocols in Microbiology May 2012Agrobacterium species are plant-associated relatives of the rhizobia. Several species cause plant diseases such as crown gall and hairy root, although there are also...
Agrobacterium species are plant-associated relatives of the rhizobia. Several species cause plant diseases such as crown gall and hairy root, although there are also avirulent species. A. tumefaciens is the most intensively studied species and causes crown gall, a neoplastic disease that occurs on a variety of plants. Virulence is specified by large plasmids, and in the case of A. tumefaciens this is called the Ti (tumor-inducing) plasmid. During pathogenesis virulent agrobacteria copy a segment of the Ti plasmid and transfer it to the plant, where it subsequently integrates into the plant genome, and expresses genes that result in the disease symptoms. A. tumefaciens has been used extensively as a plant genetic engineering tool and is also a model microorganism that has been well studied for host-microbe associations, horizontal gene transfer, cell-cell communication, and biofilm formation. This unit describes standard protocols for simple phenotypic characterizations of A. tumefaciens.
Topics: Agrobacterium tumefaciens; Bacterial Adhesion; Biofilms; Flagella; Genes, Reporter; Locomotion; Plant Tumors; Plants; beta-Galactosidase
PubMed: 22549164
DOI: 10.1002/9780471729259.mc03d03s25 -
Environmental Microbiology Jan 2018Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity... (Review)
Review
Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity in shaping the ecological and evolutionary dynamics of these facultative pathogens are incompletely understood. Agrobacterium tumefaciens, the causative agent for crown gall disease of plants has proven a productive model for many aspects of interactions between pathogens and their hosts and with other microbes. In this review, we highlight how this past work provides valuable context for the use of this system to examine how heterogeneity and transitions between disease and non-disease environments influence the ecology and evolution of facultative pathogens. We focus on several features common among facultative pathogens, such as the physiological remodelling required to colonize hosts from environmental reservoirs and the consequences of competition with host and non-host associated microbiota. In addition, we discuss how the life history of facultative pathogens likely often results in ecological tradeoffs associated with performance in disease and non-disease environments. These pathogens may therefore have different competitive dynamics in disease and non-disease environments and are subject to shifting selective pressures that can result in pathoadaptation or the within-host spread of avirulent phenotypes.
Topics: Agrobacterium tumefaciens; Biofilms; Biological Evolution; Ecology; Plant Tumors; Plants; Plasmids
PubMed: 29105274
DOI: 10.1111/1462-2920.13976 -
Plant Signaling & Behavior 2019Soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) are the key regulators control trafficking of cargo proteins to their final destinations...
Soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) are the key regulators control trafficking of cargo proteins to their final destinations and plays key role in plant development; however, their roles in plant defense remain largely unknown. R-SNARE VAMP727 and Qa-SNARE SYP22 were previously reported to associate with vacuolar protein deposition and brassinosteroids (BRs) receptor BRI1 plasma membrane targeting. Here, we identified that VAMP727 and SYP22 are induced by infection of root-knot nematode (RKN), a plant pathogen, which cause severe growth defect and yield loss. Furthermore, decreased root-knot nematode (RKN) invasion, growth and disease index were observed in bri1-5 and SYP22ND, a SYP22 negative dominant mutants when compared to control plants. Overall, our results suggest that VAMP727-SYP22 SNARE complexes regulate plant defense might be via control of abundances of BRI1 on the plasma membrane.
Topics: Animals; Arabidopsis; Arabidopsis Proteins; Brassinosteroids; Gene Expression Regulation, Plant; Mutation; Plant Immunity; Plant Tumors; Qa-SNARE Proteins; R-SNARE Proteins; SNARE Proteins; Tylenchoidea
PubMed: 31025584
DOI: 10.1080/15592324.2019.1610300 -
Philosophical Transactions of the Royal... Jul 2007The plant pathogen Agrobacterium tumefaciens induces the formation of crown gall tumours at wound sites on host plants by directly transforming plant cells. This disease... (Review)
Review
The plant pathogen Agrobacterium tumefaciens induces the formation of crown gall tumours at wound sites on host plants by directly transforming plant cells. This disease strategy benefits the bacteria as the infected plant tissue produces novel nutrients, called opines, that the colonizing bacteria can use as nutrients. Almost all of the genes that are required for virulence, and all of the opine uptake and utilization genes, are carried on large tumour-inducing (Ti) plasmids. The observation more than 25 years ago that specific opines are required for Ti plasmid conjugal transfer led to the discovery of a cell-cell signalling system on these plasmids that is similar to the LuxR-LuxI system first described in Vibrio fischeri. All Ti plasmids that have been described to date carry a functional LuxI-type N-acylhomoserine lactone synthase (TraI), and a LuxR-type signal receptor and transcriptional regulator called TraR. The traR genes are expressed only in the presence of specific opines called conjugal opines. The TraR-TraI system provides an important model for LuxR-LuxI-type systems, especially those found in the agriculturally important Rhizobiaceae family. In this review, we discuss current advances in the biochemistry and structural biology of the TraR-TraI system.
Topics: Agrobacterium tumefaciens; Conjugation, Genetic; Models, Molecular; Plant Proteins; Plant Tumors; Plants; Quorum Sensing
PubMed: 17360279
DOI: 10.1098/rstb.2007.2040 -
PloS One 2018Animal-induced galls are considered extended phenotypes of their inducers, and therefore plant morphogenesis and metabolism may vary according to the species of gall...
Animal-induced galls are considered extended phenotypes of their inducers, and therefore plant morphogenesis and metabolism may vary according to the species of gall inducers. The alterations in vacuolar and apoplastic polyphenols, carotenoids, chlorophyll fluorescence rates, PSII quantum yield, and phospholipid peroxidation were studied in galls induced by Ditylenchus gallaeformans (Nematoda) on Miconia albicans and M. ibaguensis (Melastomataceae), and by an unidentified Eriophyidae (Acarina) on M. ibaguensis. The focus currently addressed is gall metabolism as the extended phenotype of the gall inducers, and the neglected determination of gall functionalities over host plant peculiarities. Galls induced by D. gallaeformans on M. albicans and by the Eriophyidae on M. ibaguensis have increased accumulation of apoplastic and vacuolar phenolics, which is related to the control of phospholipid peroxidation and photoprotection. The galls induced by D. gallaeformans on M. ibaguensis have higher carotenoid and vacuolar polyphenol contents, which are related to excessive sunlight energy dissipation as heat, and photoprotection. Accordingly, antioxidant strategies varied according to the gall-inducing species and to the host plant species. The distinctive investments in carotenoid and/or in polyphenol concentrations in the studied galls seemed to be peculiar mechanisms to maintain oxidative homeostasis. These mechanisms were determined both by the stimuli of the gall-inducing organism and by the intrinsic physiological features of the host plant species. Therefore, the roles of both associated organisms in host plant-galling organisms systems over gall metabolism is attested.
Topics: Animals; Antioxidants; Carotenoids; Chlorophyll; Lipid Peroxidation; Melastomataceae; Nematoda; Phenotype; Plant Leaves; Plant Tumors; Polyphenols; Reactive Oxygen Species; Water
PubMed: 30346955
DOI: 10.1371/journal.pone.0205364 -
The Plant Cell Feb 2018The maize smut fungus is a model organism for elucidating host colonization strategies of biotrophic fungi. Here, we performed an in depth transcriptional profiling of...
The maize smut fungus is a model organism for elucidating host colonization strategies of biotrophic fungi. Here, we performed an in depth transcriptional profiling of the entire plant-associated development of wild-type strains. In our analysis, we focused on fungal metabolism, nutritional strategies, secreted effectors, and regulatory networks. Secreted proteins were enriched in three distinct expression modules corresponding to stages on the plant surface, establishment of biotrophy, and induction of tumors. These modules are likely the key determinants for virulence. With respect to nutrient utilization, we observed that expression of several nutrient transporters was tied to these virulence modules rather than being controlled by nutrient availability. We show that oligopeptide transporters likely involved in nitrogen assimilation are important virulence factors. By measuring the intramodular connectivity of transcription factors, we identified the potential drivers for the virulence modules. While known components of the mating type cascade emerged as inducers for the plant surface and biotrophy module, we identified a set of yet uncharacterized transcription factors as likely responsible for expression of the tumor module. We demonstrate a crucial role for leaf tumor formation and effector gene expression for one of these transcription factors.
Topics: Biomass; Fungal Proteins; Gene Expression Profiling; Membrane Transport Proteins; Nitrogen; Plant Diseases; Plant Tumors; Sequence Analysis, RNA; Transcription Factors; Transcriptome; Ustilago; Virulence; Virulence Factors; Zea mays
PubMed: 29371439
DOI: 10.1105/tpc.17.00764 -
Journal of Bacteriology Apr 2023Agrobacterium tumefaciens incites the formation of readily visible macroscopic structures known as crown galls on plant tissues that it infects. Records from biologists... (Review)
Review
Agrobacterium tumefaciens incites the formation of readily visible macroscopic structures known as crown galls on plant tissues that it infects. Records from biologists as early as the 17th century noted these unusual plant growths and began examining the basis for their formation. These studies eventually led to isolation of the infectious agent, A. tumefaciens, and decades of study revealed the remarkable mechanisms by which A. tumefaciens causes crown gall through stable horizontal genetic transfer to plants. This fundamental discovery generated a barrage of applications in the genetic manipulation of plants that is still under way. As a consequence of the intense study of A. tumefaciens and its role in plant disease, this pathogen was developed as a model for the study of critical processes that are shared by many bacteria, including host perception during pathogenesis, DNA transfer and toxin secretion, bacterial cell-cell communication, plasmid biology, and more recently, asymmetric cell biology and composite genome coordination and evolution. As such, studies of A. tumefaciens have had an outsized impact on diverse areas within microbiology and plant biology that extend far beyond its remarkable agricultural applications. In this review, we attempt to highlight the colorful history of A. tumefaciens as a study system, as well as current areas that are actively demonstrating its value and utility as a model microorganism.
Topics: Agrobacterium tumefaciens; Host Microbial Interactions; Plant Tumors; Plant Diseases; Plants; Bacteria; Biology
PubMed: 36892285
DOI: 10.1128/jb.00005-23 -
The New Phytologist Jan 2018During Agrobacterium (Agrobacterium tumefaciens) infection, the translocated virulence proteins (VirD2, VirE2, VirE3, VirF and VirD5) play crucial roles. It is thought...
During Agrobacterium (Agrobacterium tumefaciens) infection, the translocated virulence proteins (VirD2, VirE2, VirE3, VirF and VirD5) play crucial roles. It is thought that, through protein-protein interactions, Agrobacterium uses and abuses host plant factors and systems to facilitate its infection. Although some molecular functions have been revealed, the roles of VirD5 still need to be further elucidated. Here, plant transformation and tumorigenesis mediated by genetically modified Agrobacterium strains were performed to examine VirD5 roles. In addition, protein-protein interaction-associated molecular and biochemistry technologies were used to reveal and elucidate VirD5 interaction with Arabidopsis VirE2 interacting protein 2 (VIP2). Our results showed that deleting virD5 from Agrobacterium reduced its tumor formation ability and stable transformation efficiency but did not affect the transient transformation efficiency. We also found that VirD5 can interact with Arabidopsis VIP2. Further experiments demonstrated that VirD5 can affect VIP2 binding to cap-binding proteins (CBP20 and CBP80). The tumorigenesis efficiency for cbp80 mutant was not significantly changed, but that for cbp20, cbp20cbp80 mutants were significantly increased. This work demonstrates experimentally that VirD5 is required for efficient Agrobacterium infection and may promote this process by competitive interaction with Arabidopsis VIP2. CBP20 is involved in the Agrobacterium infection process and its effect can be synergistically enhanced by CBP80.
Topics: Agrobacterium tumefaciens; Arabidopsis; Arabidopsis Proteins; Gene Deletion; Plant Tumors; Protein Binding; Protein Transport; Transcription Factors, General; Transformation, Genetic; Virulence Factors
PubMed: 29084344
DOI: 10.1111/nph.14854 -
The New Phytologist Apr 2018Gibberellin (GA) regulates various plant growth and developmental processes, but its role in pathogen attack, and especially nematode-plant interactions, still remains...
Gibberellin (GA) regulates various plant growth and developmental processes, but its role in pathogen attack, and especially nematode-plant interactions, still remains to be elucidated. An in-depth characterization of the role of GA in nematode infection was conducted using mutant lines of rice, chemical inhibitors, and phytohormone measurements. Our results showed that GA influences rice-Meloidogyne graminicola interactions in a concentration-dependent manner. Foliar spray of plants with a low concentration of gibberellic acid enhanced nematode infection. Biosynthetic and signaling mutants confirmed the importance of gibberellin for rice susceptibility to M. graminicola infection. Our study also demonstrates that GA signaling suppresses jasmonate (JA)-mediated defense against M. graminicola, and likewise the JA-induced defense against M. graminicola requires SLENDER RICE1 (SLR1)-mediated repression of the GA pathway. In contrast to observations from other plant-pathogen interactions, GA plays a dominant role over JA in determining susceptibility to M. graminicola in rice. This GA-induced nematode susceptibility was largely independent of auxin biosynthesis, but relied on auxin transport. In conclusion, we showed that GA-JA antagonistic crosstalk is at the forefront of the interaction between rice and M. graminicola, and SLR1 plays a central role in the JA-mediated defense response in rice against this nematode.
Topics: Animals; Biological Transport; Cyclopentanes; Disease Susceptibility; Gibberellins; Indoleacetic Acids; Models, Biological; Oryza; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plant Shoots; Plant Tumors; Tylenchoidea
PubMed: 29464725
DOI: 10.1111/nph.15046 -
PloS One 2023Galls are products of the hyperplasia of host plant structures induced by gall-inducing organisms and have been considered as an extended phenotype of the inducers....
Galls are products of the hyperplasia of host plant structures induced by gall-inducing organisms and have been considered as an extended phenotype of the inducers. There is little evidence regarding the effect of host plants on gall morphology. We hypothesised that the morphology and developmental pattern of galls are different because of the different location of their stimulation, even though two kinds of inducers are close relatives. We observed that horned galls and their leaflets of their host plant, Rhus chinensis required a longer rapid growth stage than fusiform galls and Rhus potaninii leaflets. The distribution of trichomes showed positional dependence. Molecular analysis showed that in the fusiform gall, the target genes that regulate the plastochron of leaflets and serration development were hardly expressed, and CUP-SHAPED COTYLEDON-2 may be a key gene that regulates the formation of the horns. In summary, horned and fusiform galls showed a developmental pattern similar to those of their host plant leaflets. We suggest that the inducing site is important in the morphology and development of galls.
Topics: Animals; Host-Parasite Interactions; Plant Tumors; Plants
PubMed: 36947530
DOI: 10.1371/journal.pone.0283464