Transfer DNA

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Ti plasmid with t-DNA region

Transfer DNA ( t-DNA for short ) is a transferable section of DNA in the form of a single strand that is cut from a circular double-stranded DNA ( plasmid ) by endonucleases .

Ti plasmid t-DNA

The tumor-inducing plasmid ( Ti plasmid ) of Agrobacterium tumefaciens plays an important role , especially in green genetic engineering in precision breeding, for the introduction of foreign DNA into crops by transfection , for example to breed more resistant crosses, to achieve higher yields or for pharmaceuticals Purposes.

The t-DNA region is about 23,000 base pairs long and is bounded on the left and right by 25 base pairs, "left border" (LB) and "right border" (RB). They serve the bacterial vir protein ( VirD1 / VirD2 ) as signaling for the interfaces of the t-DNA region (endonucleolytic cleavage), i.e. the boundary marking of the beginning and end of the t-DNA. The t-DNA contains the transgenes for the opine and phytohormone syntheses (see figure). The auxin causes the plant cells to enlarge and the cytokinin causes rapid and uncontrolled cell division, which leads to the formation of tumors ( root neck gall tumor ). The amino acid-like opines serve the bacterium as a nitrogen and carbonaceous food source, which the plant cannot metabolize. Because the sequence for the enzymes of the catabolic metabolism (opin catabolism) are located on the part of the plasmid that is not transmitted. The plant is used to produce the opines, which are then used by the bacterium.

Individual evidence

  1. ^ John Flex Jackson: Genetic Transformation of Plants. Springer Science & Business Media, 2003, ISBN 978-3-540-00292-5 , p. 23 ( limited preview in Google book search).
  2. ↑ a b Wilfried Janning, Elisabeth Knust: Genetics: General Genetics - Molecular Genetics - Developmental Genetics . Ed .: Thieme. Georg Thieme Verlag , 2008, ISBN 978-3-13-128772-4 , p. 576 ( entry in Google book search).
  3. ↑ Peter Brandt: Transgenic Plants: Production, Use, Risks and Guidelines . Ed .: Springer. Springer Verlag, 2013, ISBN 978-3-0348-7962-0 , pp. 364 ( entry in Google book search).
  4. ↑ Compact Lexicon of Biology. Spektrum.de, 2001, accessed December 9, 2018 .