Agrobacterium tumefaciens is called the “natural genetic engineer of plants” because it naturally transfers a part of its Ti plasmid (T-DNA) into plant cells, causing tumor formation and integrating its DNA into the plant genome. This ability is exploited in genetic engineering to introduce desired genes into plants.

• Yeast → used in fermentation, not natural gene transfer in plants

• E. coli → common cloning host

• Mycoplasma → lacks cell wall, not involved in gene transfer

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