Question

Describe Ti plasmid of Agrobacterium - How it works, what it does in plant cells. How has this feature of Agrobacterium been used to produce transgenic plants in agriculture? What characteristics have been altered in plants?

Answer 1

The Ti plasmid or the tumor-inducing plasmid is the special high-mobility and highly transfective plasmid of Agrobacterium tumefaciens. This plasmid is very concisely designed to carry nearly 200 kbp of DNA with high GC content and maximum possible coding region. This plasmid has high transfection capability and hence tends to insert its genes into the host cells, i.e. plants. When inserted into the plant cells, the highly expressive promoter of this plasmid tends to express its genes and thus scause crown-gall disease in the plants as a result of extensive cellular growth.

Owing to its properties of high transfection, this plasmid is engineered to insert the gene of interest so that it might be inserted into the host plant once the bacterium infects it. In this regard, multiple horizontal and vertical gene trasfer strategies have been fulfilled.

As a result, following properties of plants have been engineered using this plasmid:

1. Transferring genes for increased fruit growth
2. Enhanced survivability under high temperature
3. Improved tolerance against high salt in the soil/water
4. Ability to tolerate low moisture content in the enviroment