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But despite the development from two kingdoms to five among most scientists, some authors as late as 1975 continued to employ a traditional two-kingdom system of animals and plants, dividing the plant kingdom into subkingdoms Prokaryota (bacteria and cyanobacteria), Mycota (fungi and supposed relatives), and Chlorota (algae and land plants). [14]
The term plasmid was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." [14] [15] The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time ...
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 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 DNA into plants.
Many plant expression vectors are based on the Ti plasmid of Agrobacterium tumefaciens. [31] In these expression vectors, DNA to be inserted into plant is cloned into the T-DNA, a stretch of DNA flanked by a 25-bp direct repeat sequence at either end, and which can integrate into the plant genome. The T-DNA also contains the selectable marker.
In 1907 a bacterium that caused plant tumors, Agrobacterium tumefaciens, was discovered and in the early 1970s the tumor inducing agent was found to be a DNA plasmid called the Ti plasmid. [25] By removing the genes in the plasmid that caused the tumor and adding in novel genes researchers were able to infect plants with A. tumefaciens and let ...
The pBR322 plasmid is one of the first plasmids widely used as a cloning vector. Plasmids with specially-constructed features are commonly used in laboratory for cloning purposes . These plasmid are generally non-conjugative but may have many more features, notably a " multiple cloning site " where multiple restriction enzyme cleavage sites ...
They are the standard cloning vectors and the ones most commonly used. Most general plasmids may be used to clone DNA inserts of up to 15 kb in size. One of the earliest commonly used cloning vectors is the pBR322 plasmid. Other cloning vectors include the pUC series of plasmids, and a large number of different cloning plasmid vectors are ...
With the identification of the Ti plasmid, many studies were carried out to determine the characteristics of the Ti plasmid and how the genetic material is transferred from the Agrobacterium to the plant host. Some notable early milestones in the studies of Ti plasmids include the mapping of a Ti plasmid in 1978 and the studying of sequence ...