Transfer DNA

The transfer DNA (abbreviated T-DNA) is the transferred <a href="/facts/DNA/nB89Iauz">DNA</a> of the <a href="/facts/Ti_plasmid/mV17D061">tumor-inducing (Ti) plasmid</a> of some species of bacteria such as <a href="/facts/Agrobacterium_tumefaciens/aN1LUWQY">Agrobacterium tumefaciens</a> and <a href="/facts/Agrobacterium_rhizogenes/c8xszpxm">Agrobacterium rhizogenes</a> (actually an Ri plasmid). The T-DNA is transferred from bacterium into the host plant's <a href="/facts/Cell_nucleus/D7sFRa3c">nuclear</a> DNA <a href="/facts/Genome/31Sm08JT">genome</a>. The capability of this specialized tumor-inducing (Ti) plasmid is attributed to two essential regions required for DNA transfer to the host cell. The T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the right border and terminated at the left border and requires the vir genes of the Ti plasmid.
The bacterial T-DNA is about 24,000 base pairs long and contains plant-expressed <a href="/facts/Gene/e1swwPY6">genes</a> that code for <a href="/facts/Enzyme/DSI1Fh7y">enzymes</a> synthesizing <a href="/facts/Opines/sDcaG77t">opines</a> and <a href="/facts/Phytohormone/h3noouev">phytohormones</a>. 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 <a href="/facts/Auxin/xpgQXhwo">auxin</a> and <a href="/facts/Cytokinin/0YkDowo8">cytokinin</a> by enzymes encoded in the T-DNA enables the plant cell to overgrow, thus forming the <a href="/facts/Crown_gall_tumor/eu45qB2S">crown gall tumors</a> typically induced by Agrobacterium tumefaciens infection. Agrobacterium rhizogenes causes a similar infection known as <a href="/facts/Hairy_root_culture/gJFh0prc">hairy root disease</a>. The <a href="/facts/Opines/sDcaG77t">opines</a> are <a href="/facts/Amino_acid/WDxYwBny">amino acid</a> derivatives used by the bacterium as a source of carbon and energy. This natural process of <a href="/facts/Horizontal_gene_transfer/FPyUIsf2">horizontal gene transfer</a> in plants is being utilized as a tool for fundamental and applied research in plant biology through Agrobacterium tumefaciens mediated foreign gene transformation and insertional mutagenesis. Plant genomes can be engineered by use of <a href="/facts/Agrobacterium/eu45qB2S">Agrobacterium</a> for the delivery of sequences hosted in <a href="/facts/Transfer_DNA_binary_system/EE4zvpbn">T-DNA binary vectors</a>.

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Transfer DNA