Genetic Engineering and Biotechnology

The Ti plasmid (often written as T-plasmid) is derived from the bacterium Agrobacterium tumefaciens.

Plasmids are used as vectors because they can be engineered to carry foreign genes and replicate within a host organism.

The Ti plasmid of Agrobacterium tumefaciens is the standard tool used to introduce insect-resistant genes, such as those from Bacillus thuringiensis, into plants.

Flavr Savr is a genetically modified tomato  for human consumption. The transgenic plant 'Flavr Savr' tomato carries an artificial gene for slowing down the ripening process of the tomato and thus prevent it from softening and retains its natural colour , flavour and its shelf life. 

Transgenic plants are created by the introduction of foreign genes (transgenes) into the plant genome using techniques like Agrobacterium-mediated transformation or biolistics.

Transgenic plants are plants that have been genetically engineered, a breeding approach that uses recombinant DNA techniques to create plants with new characteristics. They are identified as a class of genetically modified organism (GMO). In this case, firefly's gene is transferred to the plant, hence the plant is called transgenic plant.

In Tobacco because of  biotechnology, transgenic plants produced which have low nicotine in their leaves. 

There are several methods for introducing genes into plants, including:

•     Infecting plant cells with plasmids as vectors carrying the desired gene.
•     Shooting microscopic pellets containing the gene directly into the cell.

In contrast to animals, there is no real distinction between somatic cells and germline cells. Somatic tissues of plants, e.g., root cells grown in culture

•     can be transformed in the laboratory with the desired gene;
•     grown into mature plants with flowers.

If all goes well, the transgene will be incorporated into the pollen and eggs and passed on to the next generation.
In this respect, it is easier to produce transgenic plants than transgenic animals.
 Progress is being made on several fronts to introduce new traits into plants using recombinant DNA technology.
The genetic manipulation of plants has been going on since the dawn of agriculture, but until recently this has required the slow and tedious process of cross-breeding varieties. Genetic engineering promises to speed the process and broaden the scope of what can be done.

Transgenic tomato plants expressing a truncated insect control protein gene from Bacillus thuringiensis were  protected from attack by tobacco hornworm, tobacco budworm and tomato fruit worm larvae. Filed tests involving transgenic tomato lines challenged with tobacco hornworm, tomato fruit worm and tomato pin worm were conducted for two years. These transgenic plants suffered only minor feeding damage from tobacco hornworm, while the untransformed controls were completely defoliated. The foreign gene present had made this possible.

A tumor (crown gall) inducing plasmid widely used in the production of transgenic plants is Agrobacterium tumefaciens. Bacillus thuringiensis is used for the production of disease-resistant plants. Other 2 are disease-causing bacteria.

The tobacco plant was genetically modified by introducing a gene to produce antibodies. The plant was introduced with the gene for producing antibodies against the rabies virus which are similar to the antibodies produced in the humans. The antibodies from the plant can be purified and used as injections or vaccines. These vaccines help in providing immunity against the rabies virus.