Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual mode of reproduction in bacteria.
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the internet.
Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed.
An expression vector, otherwise known as an expression construct, is usually a plasmid or virus designed for gene expression in cells. The vector is used to introduce a specific gene into a target cell, and can commandeer the cell's mechanism for protein synthesis to produce the protein encoded by the gene. Expression vectors are the basic tools in biotechnology for the production of proteins.
In molecular biology and genetics, transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s). For transformation to take place, the recipient bacterium must be in a state of competence, which might occur in nature as a time-limited response to environmental conditions such as starvation and cell density, and may also be induced in a laboratory.
Agrobacterium tumefaciens is the causal agent of crown gall disease 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, from a plasmid into the plant cell, which is incorporated at a semi-random location into the plant genome. Plant genomes can be engineered by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors.
Agrobacterium is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. Agrobacterium tumefaciens is the most commonly studied species in this genus. Agrobacterium is well known for its ability to transfer DNA between itself and plants, and for this reason it has become an important tool for genetic engineering.
In genetic engineering, a gene gun or biolistic particle delivery system is a device used to deliver exogenous DNA (transgenes), RNA, or protein to cells. By coating particles of a heavy metal with a gene of interest and firing these micro-projectiles into cells using mechanical force, an integration of desired genetic information can be introduced into desired cells. The technique involved with such micro-projectile delivery of DNA is often referred to as biolistics, short for "biological ballistics".
A tumour inducing (Ti) plasmid is a plasmid found in pathogenic species of Agrobacterium, including A. tumefaciens, A. rhizogenes, A. rubi and A. vitis.
Gene delivery is the process of introducing foreign genetic material, such as DNA or RNA, into host cells. Gene delivery must reach the genome of the host cell to induce gene expression. Successful gene delivery requires the foreign gene delivery to remain stable within the host cell and can either integrate into the genome or replicate independently of it. This requires foreign DNA to be synthesized as part of a vector, which is designed to enter the desired host cell and deliver the transgene to that cell's genome. Vectors utilized as the method for gene delivery can be divided into two categories, recombinant viruses and synthetic vectors.
Plant transformation vectors are plasmids that have been specifically designed to facilitate the generation of transgenic plants. The most commonly used plant transformation vectors are termed T-DNA binary vectors and are often replicated in both E. coli, a common lab bacterium, and Agrobacterium tumefaciens, a plant-virulent bacterium used to insert the recombinant (customized) DNA into plants. Plant Transformation vectors contain three key elements;
A transfer DNA (T-DNA) binary system is a pair of plasmids consisting of a T-DNA binary vector and a virhelper plasmid. The two plasmids are used together to produce genetically modified plants. They are artificial vectors that have been derived from the naturally occurring Ti plasmid found in bacterial species of the genus Agrobacterium, such as A. tumefaciens. The binary vector is a shuttle vector, so-called because it is able to replicate in multiple hosts.
Acetosyringone is a phenolic natural product and a chemical compound related to acetophenone and 2,6-dimethoxyphenol. It was first described in relation to lignan/phenylpropanoid-type phytochemicals, with isolation from a variety of plant sources, in particular, in relation to wounding and other physiologic changes.
Genetic engineering techniques allow the modification of animal and plant genomes. Techniques have been devised to insert, delete, and modify DNA at multiple levels, ranging from a specific base pair in a specific gene to entire genes. There are a number of steps that are followed before a genetically modified organism (GMO) is created. Genetic engineers must first choose what gene they wish to insert, modify, or delete. The gene must then be isolated and incorporated, along with other genetic elements, into a suitable vector. This vector is then used to insert the gene into the host genome, creating a transgenic or edited organism.
EHA101 was one of the first and most widely used Agrobacterium helper plasmid for plant gene transfer. Created in 1985 in the laboratory of Mary-Dell Chilton at Washington University in St. Louis, it was named after the graduate student who constructed it. The EH stands for "Elizabeth Hood" and A for "Agrobacterium". The EHA101 helper strain is a derivative of A281, the hypervirulent A. tumefaciens strain that causes large, fast-growing tumors on solanaceous plants. This strain is used for moving genes of interest into many hundreds of species of plants all over the world.
Allorhizobium vitis is a plant pathogen that infects grapevines. The species is best known for causing a tumor known as crown gall disease. One of the virulent strains, A. vitis S4, is responsible both for crown gall on grapevines and for inducing a hypersensitive response in other plant species. Grapevines that have been affected by crown gall disease produce fewer grapes than unaffected plants. Though not all strains of A. vitis are tumorigenic, most strains can damage plant hosts.
Transient expression, more frequently referred to "transient gene expression", is the temporary expression of genes that are expressed for a short time after nucleic acid, most frequently plasmid DNA encoding an expression cassette, has been introduced into eukaryotic cells with a chemical delivery agent like calcium phosphate (CaPi) or polyethyleneimine (PEI). However, unlike "stable expression," the foreign DNA does not fuse with the host cell DNA, resulting in the inevitable loss of the vector after several cell replication cycles. The majority of transient gene expressions are done with cultivated animal cells. The technique is also used in plant cells; however, the transfer of nucleic acids into these cells requires different methods than those with animal cells. In both plants and animals, transient expression should result in a time-limited use of transferred nucleic acids, since any long-term expression would be called "stable expression."
Pal Maliga is a plant molecular biologist. He is Distinguished Professor of Plant Biology and Laboratory Director at the Waksman Institute of Microbiology, Rutgers University. He is known for developing the technology of chloroplast genome engineering in land plants and its applications in basic science and biotechnology.
Patricia C. Zambryski is a plant and microbial scientist known for her work on Type IV secretion and cell-to-cell transport in plants. She is also professor emeritus at the University of California, Berkeley.
The root inducing (Ri) -plasmid of Rhizobium rhizogenes is a plasmid capable of undergoing horizontal gene transfer of its transfer DNA (T-DNA), upon contact with a plant host. The T-DNA of the Ri-plasmid affects the plant host in such a way, that gene expression is altered, especially in regard to phytohormonal balances, metabolism and certain phenotypical characteristics.
