Plant biotechnology
Definition, scope in crop production and role in plant breeding.
What plant biotechnology is
Biotechnology is the use of living organisms, cells or their parts to make useful products or processes. Plant biotechnology includes tissue culture and genetic engineering (recombinant DNA technology), in which a desired gene from any organism is inserted into a plant to make a transgenic (genetically modified, GM) plant.
Tools: restriction enzymes ("molecular scissors") cut DNA at specific sites; DNA ligase joins pieces; vectors carry the gene into the cell. The soil bacterium Agrobacterium tumefaciens naturally transfers part of its Ti plasmid into plant cells, so it is called a natural genetic engineer and is widely used as a vector. Genes can also be shot into cells with a gene gun (particle bombardment).
Scope in crop production and role in breeding:
- Insect resistance: Bt cotton carries *cry* genes from the bacterium Bacillus thuringiensis; the Cry protein kills bollworm larvae. Bt cotton was approved for commercial cultivation in India in 2002.
- Herbicide tolerance, virus resistance, and tolerance to drought and salinity.
- Nutritional quality: Golden Rice produces β-carotene (provitamin A) in the grain.
- Molecular markers and marker-assisted selection (MAS) let breeders select plants for a gene using DNA tests, faster and independent of environment.
- Micropropagation produces large numbers of uniform, disease-free plants (e.g. banana, sugarcane).
- Haploid production through anther culture shortens the time to make pure lines.
- Biofertilisers and biopesticides are also products of biotechnology.
In India, GM crops are evaluated for safety by the Genetic Engineering Appraisal Committee (GEAC). Concerns include gene flow to wild relatives, resistance developing in pests, and effects on biodiversity.
Key points
- Transgenic plant = plant carrying a foreign gene.
- Bt toxin genes come from Bacillus thuringiensis.
- Agrobacterium tumefaciens (Ti plasmid) = natural genetic engineer.
- Golden Rice: β-carotene.
- MAS: selection using DNA markers.
Exam tips
Questions match organisms and genes to products (Bt → cotton, β-carotene → Golden Rice) or ask which tool cuts or joins DNA.
Common mistakes
- Thinking Bt stands for "Bio-technology"; it is the bacterium Bacillus thuringiensis.
- Confusing restriction enzymes (cut) with ligase (join).