Biotechnology and Its Applications - Notes | Class 12 | Part 1: Applications in Agriculture

Biotechnology has many applications such as biopharmaceuticals, therapeutics, diagnostics, genetically modified crops, processed food, bioremediation, waste treatment and energy production.
Biotechnology has 3 critical research areas:
a.    Providing the best catalyst in the form of improved organism usually a microbe or enzyme.

b.    Creating optimal conditions through engineering for a catalyst to act.

c.    Downstream processing technologies to purify the protein/organic compound.

3 options for increasing food production:
a. Agro-chemical based agriculture: It uses fertilizers & pesticides. Expensive. Causes environmental pollution.
b.  Organic agriculture: Expensive.
c. Genetically engineered crop-based agriculture: It uses genetically modified crops. Genetically Modified Organisms (GMO) are the plants, bacteria, fungi & animals whose genes are altered by manipulation.

Advantages of genetic modification in plants:

·   It makes crops more tolerant to abiotic stresses (cold, drought, salt, heat etc.).
·   Pest-resistant crops reduce the use of chemical pesticides.
·   It reduces post-harvest losses.
·   It increases efficiency of mineral usage by plants (it prevents early exhaustion of soil fertility).
·   It enhances nutritional value of food. E.g. Golden rice (Vitamin A enriched rice).
·   To create tailor-made plants to supply alternative resources (starches, fuels, pharmaceuticals etc.) to industries.

Pest Resistant Plants

-    They act as bio-pesticide.
-    It reduces the need for insecticides.
-    E.g. Bt cotton, Bt corn, rice, tomato, potato, soyabean etc.

Bt Cotton:

- Some strains of Bacillus thuringiensis have proteins that kill insects like coleopterans (beetles), lepidopterans (tobacco budworm, armyworm) & dipterans (flies, mosquitoes).
-  B. thuringiensis forms an insecticidal protein (Bt toxin) crystal during a phase of their growth. It does not kill the Bacillus as it exists as inactive protoxins.
- When an insect ingests the toxin, it becomes active due to alkaline pH of the gut which solubilise the crystals. Toxin binds to surface of mid-gut epithelial cells creating pores. It causes cell swelling and lysis and death of the insect.
- Bt toxin genes were isolated from B. thuringiensis and incorporated into crop plants such as cotton.
- Most Bt toxins are insect-group specific. They are coded by cry genes. E.g. proteins encoded by cryIAc & cryIIAb genes control cotton bollworms. Protein of cryIAb gene controls corn borer.

Nematode resistance in tobacco plants:

-  A nematode Meloidogyne incognita infects the roots of tobacco plants causing a reduction in yield.
-  It can be prevented by RNA interference (RNAi) strategy.
-  RNAi is a method of cellular defense in all eukaryotic organisms. It prevents translation of a specific mRNA (silencing) due to a complementary dsRNA molecule.
- The source of this complementary RNA is from an infection by RNA viruses or mobile genetic elements (transposons) that replicate via an RNA intermediate.
-  Isolate Nematode-specific genes (DNA). It is introduced into host plant using Agrobacterium vectors. It produces both sense & anti-sense RNA in host cells. These RNAs are complementary. So they form double stranded (ds) RNA. It initiates RNAi and silences the specific mRNA of nematode. Thus the parasite cannot survive in a transgenic host expressing specific interfering RNA.

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