How is agrobacterium tumefaciens used in the agriculture industry

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Researchers used the natural transfer of DNA from Agrobacterium to a plant host to introduce DNA fragments of their choice into plant hosts. In nature, the disease-causing A. tumefaciens have a set of plasmids, called the Ti plasmids (tumor-inducing plasmids), that contain genes for the production of tumors in plants.

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Answer

What is the role of Agrobacterium tumefaciens in biotechnology?

The Role of Agrobacterium in Plant Biotechnology. In other words, the plant tumor cells contain transferred bacterial DNA. This is how Agrobacterium tumefaciens could change plant cells into tumor cells. Significantly, this is also the reason as to why gene exchange could be made possible between unrelated plant species.

What is A tumefaciens used for in agriculture?

A. tumefaciens have emerged as an important molecular tool for manipulating plants and creating genetically modified crops for research and agriculture. Because of its importance in the laboratory, a complete genome of A. tumefaciens strain C58 was published in 2001 (Goodner, B.).

What is the temperature of Agrobacterium tumefaciens?

At temperatures above 30 °C, A. tumefaciens begins to experience heat shock which is likely to result in errors in cell division. To be virulent, the bacterium contains tumour-inducing plasmid (Ti plasmid or pTi), of 200 kbp, which contains the T-DNA and all the genes necessary to transfer it to the plant cell.

What is Agrobacterium tumefaciens T-DNA?

Agrobacterium tumefaciens is a phytopathogenic bacterium capable of transferring a segment of its genome to plant cells. The segment, termed “T-DNA,” resides in the bacterium on a large plasmid (Ti-, tumor inducing plasmid).

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How is Agrobacterium tumefaciens used?

Agrobacterium tumefaciens is a gram-negative bacterium that uses horizontal gene transfer to create tumors in plants. Agrobacterium tumefaciens has been extensively used as major agent for the production of transgenic plants in a wide variety of plant species (Hooykaas, 1989).


How is the organism Agrobacterium tumefaciens important in agriculture?

Agrobacterium tumefaciens, a phytopathogenic bacterium in soil, transforms dicotyledonous plant cells to cause the neoplastic disease crown gall, and is used as a tool for genetic transformation of plant cells.


How is Agrobacterium tumefaciens used in the transformation of plants?

Agrobacterium tumefaciens is a soil phytopathogen that naturally infects plant wound sites and causes crown gall disease via delivery of transferred (T)-DNA from bacterial cells into host plant cells through a bacterial type IV secretion system (T4SS).


What is the role of Agrobacterium tumefaciens in the production of transgenic plants tomatoes?

What is the role of Agrobacterium tumefaciens in the production of transgenic plants? Genes from A. tumefaciens are inserted into plant DNA to give the plant different traits. Transgenic plants have been given resistance to the pest A.


What is Agrobacterium used for?

Uses in biotechnology. The ability of Agrobacterium to transfer genes to plants and fungi is used in biotechnology, in particular, genetic engineering for plant improvement. Genomes of plants and fungi can be engineered by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors.


What are the components of the Agrobacterium tumefaciens system?

The system components are a membrane sensor protein, VirA, and a cytoplasmic response regulator protein, Vir G.


What is the DNA transfer system of Agrobacterium tumefaciens?

Our current interest is on elucidating the promiscuous DNA transfer system of Agrobacterium tumefaciens. This organism uses DNA transfer in pathogenesis, which culminates in the formation of crown gall tumors on the plant host. The processes involved in preparing the DNA for transfer and for the biosynthesis of the transmembrane DNA-protein transport system are encoded by vir genes on a large resident Ti plasmid. The vir genes are arranged into six-major operons clustered within the 38.6 kb vir regulon on the Ti plasmid (Rogowsky et al., 1990 ). The vir genes become fully expressed upon perception by A. tumefaciens of chemical signals from the host plant. These signals are generated by the plant especially at wounded sites to initiate wound healing. The compounds elaborated are precursors of cork or lignin, of which the condensation precursors are dimethoxyl phenols such as sinapinic acid, ferulate and coumarate, including sinapyl alcohol, coumaryl alcohol and coniferyl alcohol (Kado, 1991). These signal molecules are detected by a transmembrane histidine kinase: VirA. The signal is transduced from VirA to the transcriptional activator VirG by transphosphorylation. The resulting effect is the expression of the remaining vir genes via this two-component signal transducing system ( Winans, 1992; Das, 1998 ).


What is the plasmid of agrobacterium?

Agrobacterium tumefaciens (recently reclassified as Rhizobium radiobacter) is a plant pathogenic bacterium that contains a plasmid, the tumor-inducing or Ti plasmid, a segment of which, called T-DNA, integrates into the host plant chromosomes causing a cancerous proliferation of the stem tissue often around the junction of the root and shoot (crown gall). Following infection, T-DNA is integrated into the plant genome and is passed on to daughter cells as an integral part of the plant DNA. T-DNA usually contains eight contiguous genes delineated by the left and right border sequences. It is the expression of these genes that induces the gall tumors, as well as the production of compounds (opines) that Agrobacterium uses as nutrients. Removal of the tumor-inducing genes, but not the left and right border sequences, and replacement by genes conferring the desirable phenotype maintains the ability of Agrobacterium to infect plant cells; infectivity is controlled by the virulence region of the Ti plasmid ( Fig. 2.10 ). T-DNA lacking the cancer-causing genes is referred to as “disarmed.” Upon infection, a sequence of 15–30 kb in the Ti plasmid, flanked by 25 bp repeat sequences on either side, is stably integrated into the plant genome and passed on to daughter cells. Bacteria containing engineered Ti plasmids are used as vehicles (vectors) carrying rDNA into plants by co-cultivating them with suitable target cells (embryogenic suspensions or callus) to enable the modified T-DNA to integrate into somatic cells. Transformed cells are then selected and regenerated into whole plants. A. tumefaciens infects mainly dicots but can also be used to transform monocots.


What is ATMT in plants?

Agrobacterium tumefaciens -mediated transformation (ATMT) of filamentous fungi is a method that originated from its use in transformation of plants. Agrobacterium tumefaciens is a gram-negative soil bacterium, which can cause crown gall tumors at wound sites of infected dicotyledonous plants.


What is the name of the bacterium that causes tumours in plants?

Agrobacterium Tumefaciens. Agrobacterium is a plant pathogenic bacterium that causes tumours (crown gall disease) in some plant species (Fig. 1A). The bacterium contains a plasmid (the tumour-inducing or Ti plasmid), part of which (the T-DNA) integrates into the host plant chromosomes (Fig. 1B).


Which bacterium is a pathogenic bacterium?

2 Agrobacterium -Mediated Transformation. Agrobacterium tumefaciens is a plant pathogenic bacterium that contains a plasmid (the tumour-inducing or Ti plasmid), part of which (the T-DNA) integrates into the host plant chromosomes ( Box 1.7 ); it has been termed “nature’s genetic engineer”.


When was Agrobacterium developed?

In the early 1980s , strains of Agrobacterium were developed that lacked the disease-causing genes but maintained the ability to attach to susceptible plant cells and transfer desired DNA that could stably integrate into the cells of target species.


What is the role of agrobacterium tumefaciens in the development of plant cells

Agrobacterium tumefaciens is a soil bacterium that has the ability to infect plant cells and transfer a defined sequence of their DNA to the plant cell by infection and a causative agent of crown gall disease. Agrobacterium tumefaciens cell contains a plasmid known as the Ti (tumor-inducing) plasmid (140–235 kb). Most of the Ti plasmids have following regions: (1) T-DNA region: responsible for tumor induction. Sequences homologous to this region are always transferred to plant nuclear genome. This region encodes the enzymes responsible for the phytohormone synthesis, so that the incorporation of these genes in plant nuclear genome leads to the synthesis of phytohormones in the host plant. The phytohormones in their turn alter the developmental program, leading to the crown gall formation. (2) An opine synthesis (OS) region responsible for the synthesis of unusual amino acid or sugar derivatives, which are collectively given the name opines. (3) On either side of the T-DNA, there is a short sequence of 24 bp called border sequence. Both the left and right border sequences are essential for tumor induction. (4) Origin of replication: responsible for replication. (5) Tra region: responsible for conjugation. (6) Inc region: responsible for incompatibility among plasmids in a bacterium. (7) Vir region: responsible for virulence region and plays a crucial role in the transfer of T-DNA into the plant nuclear genome.


What are the components of the Agrobacterium tumefaciens system?

The system components are a membrane sensor protein, VirA, and a cytoplasmic response regulator protein, Vir G.


What is the plasmid of Agrobacterium tumefaciens?

Agrobacterium tumefaciens cell contains a plasmid known as the Ti (tumor-inducing) plasmid (140–235 kb). Most of the Ti plasmids have following regions: (1) T-DNA region: responsible for tumor induction. Sequences homologous to this region are always transferred to plant nuclear genome.


How does Agrobacterium tumefaciens transfer DNA?

Agrobacterium tumefaciens is a soil bacterium, which is used to transfer a small segment of DNA into plant genome by the process known as transformation ( Mishra et al., 2008 ). The whole plant is regenerated from individual plant. In this method of gene transfer, the desired gene is inserted into T region of disarmed Ti plasmid of Agrobacterium. The recombinant DNA into Agrobacterium is cultured along with plant cells to be transformed ( Streatfield, 2006 ). The testing of these antigens produced by transgenic plants in animal experiments showed that the genes successfully expressed in these plants ( Mishra et al., 2008; Mariotti et al., 1989; Mercenier et al., 2001; Chikwamba et al., 2002; Yuki and Kiyono, 2003) Earlier this method was limited to tobacco and a few other species, but now it has been extended to vegetable species of agronomic interest like Graminae and Leguminosae ( Chikwamba et al., 2002; Lee et al., 2001 ). This method has opened new prospects for the development of edible vaccines for humans as well as for veterinary use ( Mishra et al., 2008 ).


What is the DNA transfer system of Agrobacterium tumefaciens?

Our current interest is on elucidating the promiscuous DNA transfer system of Agrobacterium tumefaciens. This organism uses DNA transfer in pathogenesis, which culminates in the formation of crown gall tumors on the plant host. The processes involved in preparing the DNA for transfer and for the biosynthesis of the transmembrane DNA-protein transport system are encoded by vir genes on a large resident Ti plasmid. The vir genes are arranged into six-major operons clustered within the 38.6 kb vir regulon on the Ti plasmid ( Rogowsky et al., 1990 ). The vir genes become fully expressed upon perception by A. tumefaciens of chemical signals from the host plant. These signals are generated by the plant especially at wounded sites to initiate wound healing. The compounds elaborated are precursors of cork or lignin, of which the condensation precursors are dimethoxyl phenols such as sinapinic acid, ferulate and coumarate, including sinapyl alcohol, coumaryl alcohol and coniferyl alcohol ( Kado, 1991 ). These signal molecules are detected by a transmembrane histidine kinase: VirA. The signal is transduced from VirA to the transcriptional activator VirG by transphosphorylation. The resulting effect is the expression of the remaining vir genes via this two-component signal transducing system ( Winans, 1992; Das, 1998 ).


What is the process of induction of tumors?

This chapter describes different tumors induced by different strains of Agrobacterium tumefaciens. Tumor induction by agrobacteria is a largely unknown process that is controlled by agrobacterial plasmid genes and possibly also by chromosomal genes of the bacteria. During tumor induction, the bacteria penetrate the intercellular spaces …


What is ATMT in plants?

Agrobacterium tumefaciens -mediated transformation (ATMT) of filamentous fungi is a method that originated from its use in transformation of plants. Agrobacterium tumefaciens is a gram-negative soil bacterium, which can cause crown gall tumors at wound sites of infected dicotyledonous plants.


How does A. tumefaciens infect a plant?

A. tumefaciens infects the plant through its Ti plasmid. The Ti plasmid integrates a segment of its DNA, known as T-DNA, into the chromosomal DNA of its host plant cells. A. tumefaciens has flagella that allow it to swim through the soil towards photoassimilates that accumulate in the rhizosphere around roots.


How do agrobacterium survive in soil?

Agrobacterium tumefaciens overwinters in infested soils. Agrobacterium species live predominantly saprophytic lifestyles, so its common even for plant-parasitic species of this genus to survive in the soil for lengthy periods of time, even without host plant presence. When there is a host plant present, however, the bacteria enter the plant tissue via recent wounds or natural openings of roots or stems near the ground. These wounds may be caused by cultural practices, grafting, insects, etc. Once the bacteria have entered the plant, they occur intercellularly and stimulate surrounding tissue to proliferate due to cell transformation. Agrobacterium performs this control by inserting the plasmid T-DNA into the plant’s genome. See above for more details about the process of plasmid DNA insertion into the host genome. Excess growth of the plant tissue leads to gall formation on the stem and roots. These tumors exert significant pressure on the surrounding plant tissue, which causes this tissue to become crushed and/or distorted. The crushed vessels lead to reduced water flow in the xylem. Young tumors are soft and therefore vulnerable to secondary invasion by insects and saprophytic microorganisms. This secondary invasion causes the breakdown of the peripheral cell layers as well as tumor discoloration due to decay. Breakdown of the soft tissue leads to release of the Agrobacterium tumefaciens into the soil allowing it to restart the disease process with a new host plant.


How does Agrobacterium transmit DNA?

The DNA transmission capabilities of Agrobacterium have been vastly explored in biotechnology as a means of inserting foreign genes into plants. Marc Van Montagu and Jeff Schell, ( University of Ghent and Plant Genetic Systems, Belgium) discovered the gene transfer mechanism between Agrobacterium and plants, which resulted in the development of methods to alter the bacterium into an efficient delivery system for genetic engineering in plants. The plasmid T-DNA that is transferred to the plant is an ideal vehicle for genetic engineering. This is done by cloning a desired gene sequence into T-DNA binary vectors that will be used to deliver a sequence of interest into eukaryotic cells. This process has been performed using firefly luciferase gene to produce glowing plants. This luminescence has been a useful device in the study of plant chloroplast function and as a reporter gene. It is also possible to transform Arabidopsis thaliana by dipping flowers into a broth of Agrobacterium: the seed produced will be transgenic. Under laboratory conditions, the T-DNA has also been transferred to human cells, demonstrating the diversity of insertion application.


What is the pTi in a plant cell?

To be virulent, the bacterium contains tumour-inducing plasmid (Ti plasmid or pTi), of 200 kbp, which contains the T-DNA and all the genes necessary to transfer it to the plant cell. Many strains of A. tumefaciens do not contain a pTi.


What is the genome of A. tumefaciens?

and Wood et al. in 2001. The genome of A. tumefaciens C58 consists of a circular chromosome, two plasmids, and a linear chromosome. The presence of a covalently bonded circular chromosome is common to Bacteria, with few exceptions.


Is tumefaciens a disease?

Economically, A. tumefaciens is a serious pathogen of walnuts, grape vines, stone fruits, nut trees, sugar beets, horse radish, and rhubarb, and the persistent nature of the tumors or galls caused by the disease make it particularly harmful for perennial crops. A. tumefaciens grows optimally at 28 °C.


Who discovered the gene transfer mechanism between Agrobacterium and plants?

Marc Van Montagu and Jeff Schell, ( University of Ghent and Plant Genetic Systems, Belgium) discovered the gene transfer mechanism between Agrobacterium and plants, which resulted in the development of methods to alter the bacterium into an efficient delivery system for genetic engineering in plants.


What is the role of A. tumefacienshave in the genome?

A. tumefacienshave emerged as an important molecular tool for manipulating plants and creating genetically modified crops for research and agriculture. Because of its importance in the laboratory, a complete genome of A. tumefaciensstrain C58 was published in 2001 (Goodner, B.). Genome structure.


Why is A. tumefacienshas so popular?

Even though other methods such as biolistic has developed to put genes inside plants, A. tumefacienshas remained popular for genetic manipulation of plants due to the low copy number of genes in plants created and stability of the transgene (Li, W.).


What is the name of the rod-shaped bacteria that lives at the root of a plant?

Agrobacterium tumefaciensis a gram-negative rod-shaped bacteria (Jin, S.) closely related to nitrogen-fixing bacteria which dwell at root nodules in legumes. Unlike most other soil-dwelling bacteria, it infects the roots of plants to cause Crown Gall Disease (Jin, S.). In the wild A. tumefacienstargets dicots, and causes economic damage …


What is the T-DNA?

The T-DNA is then integrated into the plant’s genome, and has two effects on the plant host. The T-DNA first directs the plant cells to make auxins and cytokinins, which causes the cells to become irregularly shaped and form a visible tumor called a gall (Moore, L. W.).


How many base pairs does A. tumefaciensis have?

A. tumefaciensis an unusual bacteria because is one of the few that has both a linear and a circular chromosome. Its genome has a total of 5.7 million base-pairs, with 2.8 million residing on its circular chromosome and 2.1 million residing on its linear chromosome (Goodner, B).


Why is flagella important in the life cycle?

A. tumefacienscontain flagella, which are important in their life cycle as it helps them swim through the soil to find their plant hosts. Mutations in flagella genes reduced virulence of A. tumefaciensin the laboratory. Strains with fla protein mutants could not infect plants grown naturally in soil (Chesnokova, O.).


Where does A. tumefacienscan live?

A. tumefacienscan live either freely in the soil or inside plants as a parasite. When it is a parasite it uses its plant host to produce energy for it. The form of energy the plant provides to the bacteria are opines, which few bacteria except for A. tumefacienscan use as their sole energy source.


Abstract

For years, isolation of foreign genes from one plant and transferring them to another and then observing effects of new genes in transferred plants has only been a dream for a plant biologist. Today, many commercially important species are routinely transformed by different biotechnological methods.


Notes

I would like to express my special thanks to Professor Sebahattin Özcan (Ankara University, Agronomy Department), Dr. İlhan Doğan (Izmir Institute of Technology, Department of Molecular Biology and Genetics), Dr. Ülkühan Yaşar (Bartin University, Department of Environmental Engineering) and Dr.


How does agrobacterium tumefaciens change plant cells into tumor cells?

It was found that when agrobacterium infection occurs, a part of Agrobacterium tumefaciens DNA was fused with the host plant’s genome. This is how they enter other cells. In other words, the plant tumor cells contain transferred bacterial DNA. This is how Agrobacterium tumefaciens could change plant cells into tumor cells.


What is the purpose of agrobacterium?

Uses of Agrobacterium. Agrobacterium can totally transform plants and it does so by altering the plant genome. Using Agrobacterium the following can be done. a) Make transformation protocols for new plant species, for different cultivars and variants of it.


Why is agrobacterium important?

From the research point of view, Agrobacterium is an important plant pathogen that is required for biological genetic transformation in plants and Agrobacterium transformation technologies were developed by leading international crop science players such as Bayer and others.


What is an example of agrobacterium mediated transformation?

An example of Agrobacterium mediated transformation. In semi– arid land the ideal serial crop that could be grown is sorghum. Apart from the grain it has multi-usage like for example the stover could be used as fodder. But unfortunately as regards sorghum, tissue culture and transformation are difficult to achieve.


Which organism is credited with inventing plant biotechnology that revolves around genetic engineering?

On the contrary, the microorganism Agrobacterium tumefaciens should be credited with inventing plant biotechnology that revolves around genetic engineering because this organism has been indulging in genetic manipulation as a natural process.


Can Agrobacterium tumefaciens be used to make transgenic plants?

This is how Agrobacterium tumefaciens could change plant cells into tumor cells. Significantly, this is also the reason as to why gene exchange could be made possible between unrelated plant species. This opened a window for using the natural genetic engineering capabilities of the Agrobacterium bacteria as a tool to make transgenic plants.


Do GM plants have genes?

GM plants have genes of other species artificially introduced in them— the general idea being to put in a new trait for a particular benefit. As regards this process, we human beings cannot be credited with inventing plant biotechnology that revolves around genetic engineering. On the contrary, the microorganism Agrobacterium tumefaciens should …


What is the purpose of agrobacterium?

Through a rare inter-kingdom DNA transfer, the bacteria move some of their genes into their host’s genome, thereby inducing the host cells to proliferate and produce opines, nutrients sources for the pathogen.


How do bacteria transfer genes?

Bacteria of the genus Agrobacterium are very useful and unusual plant pathogens. Through a rare inter-kingdom DNA transfer, the bacteria move some of their genes into their host’s genome, there by inducing the host cells to proliferate and produce opines, nutrients sources for the pathogen. Agrobacterium’s ability to transfer DNA makes can be adapted to introduce other genes, such as those encoding useful traits, into plant genomes. The development of Agrobacterium as a tool to transform plants is a landmark event in modern plant biology. This lecture provides an introduction to Agrobacterium tumefaciens and related species, focusing on their modes of pathogenicity, their usefulness as tools for plant transformation, and their use as a model for the study of plant-pathogen interactions.

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Overview

Agrobacterium radiobacter (more commonly known as Agrobacterium tumefaciens) is the causal agent of crown gall disease (the formation of tumours) in over 140 species of eudicots. It is a rod-shaped, Gram-negative soil bacterium. Symptoms are caused by the insertion of a small segment of DNA (known as the T-DNA, for ‘transfer DNA’, not to be confused with tRNA that transfers amino acids during protein synthesis), from a plasmid into the plant cell, which is incorporated at a se…


Conjugation

To be virulent, the bacterium contains tumour-inducing plasmid (Ti plasmid or pTi), of 200 kbp, which contains the T-DNA and all the genes necessary to transfer it to the plant cell. Many strains of A. tumefaciens do not contain a pTi.
Since the Ti plasmid is essential to cause disease, prepenetration events in the rhizosphere occur to promote bacterial conjugation – exchange of plasmids amongst bacteria. In the presence of opi…


Infection methods

Agrobacterium tumefaciens infects the plant through its Ti plasmid. The Ti plasmid integrates a segment of its DNA, known as T-DNA, into the chromosomal DNA of its host plant cells. A. tumefaciens has flagella that allow it to swim through the soil towards photoassimilates that accumulate in the rhizosphere around roots. Some strains may chemotactically move towards che…


Genes in the T-DNA

To cause gall formation, the T-DNA encodes genes for the production of auxin or indole-3-acetic acid via the IAM pathway. This biosynthetic pathway is not used in many plants for the production of auxin, so it means the plant has no molecular means of regulating it and auxin will be produced constitutively. Genes for the production of cytokinins are also expressed. This stimulates cell proliferation and gall formation.


Biotechnological uses

The Asilomar Conference (Berg et al. 1975) established widespread agreement that recombinant techniques were insufficiently understood and needed to be tightly controlled. The DNA transmission capabilities of Agrobacterium have been vastly explored in biotechnology as a means of inserting foreign genes into plants. Shortly after Asilomar, Marc Van Montagu and Jeff Schell, (University of …


Natural genetic transformation

Natural genetic transformation in bacteria is a sexual process involving the transfer of DNA from one cell to another through the intervening medium, and the integration of the donor sequence into the recipient genome by homologous recombination. A. tumefaciens can undergo natural transformation in soil without any specific physical or chemical treatment.


Disease cycle

Agrobacterium tumefaciens overwinters in infested soils. Agrobacterium species live predominantly saprophytic lifestyles, so its common even for plant-parasitic species of this genus to survive in the soil for lengthy periods of time, even without host plant presence. When there is a host plant present, however, the bacteria enter the plant tissue via recent wounds or natural openings of ro…


Disease management

Crown gall disease caused by Agrobacterium tumefaciens can be controlled by using various different methods. The best way to control this disease is to take preventative measures, such as sterilizing pruning tools so as to avoid infecting new plants. Performing mandatory inspections of nursery stock and rejecting infected plants as well as not planting susceptible plants in infected fields are also valuable practices. Avoiding wounding the crowns/roots of the plants during culti…


Classification

  • Higher order taxa
    Bacteria (Domain); Proteobacteria (Phylum); Alphaproteobacteria (Class); Rhizobiales (Order); Rhizobiaceae (Family); Agrobacterium (Genus)
  • Species
    Agrobacterium tumefaciens

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Description and Significance

  • Agrobacterium tumefaciens is a gram-negative rod-shaped bacteria (Jin, S.) closely related to nitrogen-fixing bacteria which dwell at root nodules in legumes. Unlike most other soil-dwelling bacteria, it infects the roots of plants to cause Crown Gall Disease (Jin, S.). In the wild A. tumefaciens targets dicots, and causes economic damage to plants…

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Genome Structure

  • A. tumefaciensis an unusual bacteria because is one of the few that has both a linear and a circular chromosome. Its genome has a total of 5.7 million base-pairs, with 2.8 million residing on its circular chromosome and 2.1 million residing on its linear chromosome (Goodner, B). Most of the genes essential for its survival are located on the circular chromosome, although through ev…

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Pathology

  • A. tumefaciens infects plants usually through an open wound. It seeks out phenolic compounds which spills from a plant wound and chemotactically moves toward its source. Once it enters its plant host, it injects a section of its DNA called the T-DNA which is derived from its Ti (tumor inducing) plasmid into its host (Moore, L. W.). The T-DNA is then integrated into the plant’s geno…

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Cell Structure and Metabolism

  • A. tumefaciens contain flagella, which are important in their life cycle as it helps them swim through the soil to find their plant hosts. Mutations in flagella genes reduced virulence of A. tumefaciensin the laboratory. Strains with fla protein mutants could not infect plants grown naturally in soil (Chesnokova, O.). The bacterium swims towards concentration of phenolic com…

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Ecology

  • A. tumefaciens can live either freely in the soil or inside plants as a parasite. When it is a parasite it uses its plant host to produce energy for it. The form of energy the plant provides to the bacteria are opines, which few bacteria except for A. tumefaciens can use as their sole energy source. This gives rise to the “Opine Hypothesis” which states that A. tumefaciens is the main beneficiary of t…

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Application to Biotechnology

  • Due to its ability to integrate DNA into its plant hosts, A. tumefaciens have been used to make transgenic plants since the 1970’s. Even though other methods such as biolistic has developed to put genes inside plants, A. tumefaciens has remained popular for genetic manipulation of plants due to the low copy number of genes in plants created and stability of the transgene (Li, W.). Th…

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Current Research

  • A. agrobacterium continues to be one of the oldest and most commonly used technique for transfecting genes into plants. Recent research to produce cellulase has used to express a bacterial cellulase gene in Lemna minor (duckweed) using A. agrobacterium. As the interest in producing cellulosic ethanol has increase, a method for breaking down cellulose into sugars is b…

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