Transgenic plants: Production and applications

Transgenic Plant:-

•   Definition:- Stable transformation is achieved when a desired gene is integrated into the genome of a plant, this plant is called transgenic plant.

•      These transgenic plants are developed for the following purposes:-

1. Insect Resistance

2. Virus Resistance

3. Seed Protein Quality

4. Gene Silencing

5. Male Sterility

6. Biochemical Production

1. Insect Resistance:-

 cry gene transfer:- The cry gene is found in the plasmid of Bacillus thuringiensis (Bt) bacteria. This cry gene makes Crystal protein which is insecticidal.

Ø The cry gene was isolated from the plasmid of Bt and integrated into the cotton genome to form a transgenic plant called Bt-cotton.

Ø This Bt - cotton is resistant to boll worm.

Ø Crystal protein perforates the larva's alimentary canal leading to its death.

2. Virus Resistance:-

cp – gene transfer:- The coat protein is transferred from the TMV virus to the tobacco plant.

Ø The RNA of TMV virus is not come out in the presence of cp-protein. Due to which the tobacco plant becomes resistant to mosaic disease.

Ø Other examples: - Tomato, Alfalfa, Beetroot, Potato

3. Seed Protein Quality:-

SFA8 gene transfer:- In sunflower seeds, the SFA8 gene produces a protein that contains an excess of sulfur-rich amino acids methionine and cysteine. While the proteins present in pea seeds lack methionine and cysteine ​​amino acids.

Ø Therefore the SFA8 gene is transferred to pea seeds.

4. Gene Silencing:-

Slow ripening tomatoes:-

Ø  PG (Poly Galacturonase) enzyme digest the pectin. Due to which fruits become soft and fluffy quickly and ripen quickly.

Ø  Anti-sense genes are integrated into the genome of tomato plants against genes that code PG enzymes. This inhibits the expression of PG gene and the tomato fruit ripens late.

Ø Antisense gene made against PG gene inhibits its expression, which causes tomato to ripen late and can be easily exported.

5. Male Sterility:-

Producing male sterility:-

Ø Flavonoid are essential for maturation of pollens. If we stop its formation then male sterility can be created in the plant.

Ø  The CHS (Chalcone Synthase) enzyme is required for flavonoid synthesis.

Ø  Anti-sense genes are integrated into the plant's genome against genes that code CHS.

Ø  Absence of a flavonoid causes pollen to become inactive. The plant becomes male sterile.

6. Biochemical Production:-

•      PHB (Poly Hydroxy Butyrate):- It is prepared from Acetyl CoA. From this bio-degradable plastic is made.

•    The transgenic plant is developed by isolating the phb - B and phb - C genes from the Alcaligenes eutrophus bacterium and transfer to Arabidopsis thaliana. Now PHB is obtained from this plant.

Golden Rice:-

•      The genes that form β - carotene are integrated into the embryo of rice within the genome to prepare golden rice.

•      2 genes are isolated from Daffodils plant and 1 gene from Erwinia uredovora bacterium.

•   β - carotene is yellow in color, which makes rice yellow.

•   β - carotene is the precurssor of vitamin A.