T-DNA is the transferred DNA of the tumor-inducing (Ti) plasmid of some species of bacteria such as Agrobacterium tumefaciens and Agrobacterium rhizogenes. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ti plasmid is a circular Plasmid that often but not always is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium Agrobacterium tumefaciens is the causal agent of Crown Gall disease (the formation of Tumours in over 140 species of Dicot. Agrobacterium rhizogenes is a Gram negative soil bacterium In the Rhizosphere, plants may suffer from wounds by soil Pathogens or other sources It derives its name from the fact that the bacterium transfers this DNA fragment into the host plant's nuclear DNA genome. In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed In classical genetics the genome of a Diploid Organism including Eukarya refers to a full set of chromosomes or genes in a Gamete, thereby The T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the left border and terminated at the right border and requires the vir genes of the Ti plasmid.
The bacterial T-DNA is about 20,000 base pairs long and contains genes that code for enzymes synthesizing opines and phytohormones. History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Opine (noun is a joint project of Google and the University of Washington to produce a Search engine that distills the most important information about Plant hormones (also known as phytohormones) are chemicals that regulate plant growth By transferring the T-DNA into the plant genome, the bacterium essentially reprograms the plant cells to grow into a tumor and produce a unique food source for the bacteria. The synthesis of the plant hormones auxin and cytokinin enables the plant cell to grow uncontrollably, thus forming the crown gall tumors typically induced by Agrobacterium infection. Auxins are a class of Plant growth substance (often called Phytohormone or Plant hormone) Cytokinins (CK are a class of Plant growth substances ( Plant Hormones that promote Cell division. The opines are amino acid derivatives used by the bacterium as a source of carbon and energy. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this
T-DNA transformation
Agrobacterium-mediated T-DNA transfer is widely used as a tool in biotechnology. Biotechnology is Technology based on Biology, especially when used in Agriculture, Food science, and Medicine. In genetic engineering, the tumor-promoting and opine-synthesis genes are removed from the T-DNA and replaced with a gene of interest and/or a selection marker. Genetic engineering, Recombinant DNA technology, genetic modification/manipulation (GM and gene splicing are terms that apply to the direct Agrobacterium is then used as a vector to transfer the engineered T-DNA into the plant cells where it integrates into the plant genome. This method can be used to generate transgenic plants carrying a foreign gene. Transgenic plants possess a Gene or genes that have been transferred from a different Species.
T-DNA mutagenesis
The same procedure of T-DNA transfer can be used to disrupt genes via insertional mutagenesis. Insertional mutagenesis is Mutagenesis of dna by the insertion of one or more bases Not only does the inserted T-DNA sequence create a mutation but it also 'tags' the affected gene, thus allowing for its isolation. This method is used widely to study gene function in plants, such as the model plant Arabidopsis thaliana. Arabidopsis thaliana ( A-ra-bi-dóp-sis tha-li-á-na; thale cress, mouse-ear cress or Arabidopsis) is a small
References
- P. H. Raven, R. F. Evert, S. E. Eichhorn (2005): Biology of Plants, 7th Edition, W. H. Freeman and Company Publishers, New York, ISBN 0-7167-1007-2
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