PLANTBI 40 Lecture Notes - Lecture 13: Agrobacterium Tumefaciens, Ti Plasmid, Cytokinin
7 Aug 2018
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Agrobacterium tumefaciens (makes tumors) called crown galls : pathogen. Transgene: genetic material that has been transferred by gene engineering methods: classical breeding (slow, random, only specific species) 2. Genetic engineering (recombinant dna technology, vector to transfer dna, ability to manipulate the cell) Armin braun found that tumors (crown galls) did not contain bacteria. Therefore the bacteria must transfer something, which he called the tip. Tip = t-dna from the tumor inducing plasmid (circular dna) Crown gall tumors are due to the over production of both auxin and cytokinin in the tumor cells. T-dna genes 1 and 2 produce auxin, and gene 4 produces cytokinin. There are 25 base pair repeats of dna that are called t-dna borders as they defined the boundary between the t-dna element and plant sequences. Directly repeated, i. e. in the same orientation or polarity. Such smaller plasmids are easier to manipulate by recombinant dna technology. But bacteria are clever and quickly evolve genes to detoxify antibiotics.
