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GATE 2023 BT – Question 44

Plant, Animal and Microbial Biotechnology · Plants: Hairy root culture, artificial seeds, somaclonal variation, protoplast fusion, transgenic plants, marker genes, plastid transformation · 2 marks · Multiple select

Direct DNA transfer method(s) used for plant genetic engineering is(are)

  1. microparticle bombardment
  2. electroporation
  3. polyethylene glycol treatment
  4. Agrobacterium-mediated transformation

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Correct answer: (A) microparticle bombardment; (B) electroporation; (C) polyethylene glycol treatment

Explanation

Plant transformation methods are either **vector-mediated** or **direct DNA transfer**.

Direct (vectorless) methods deliver naked DNA to the cell:
- **Microparticle bombardment (gene gun):** DNA-coated gold or tungsten particles are shot into the cells. ✓
- **Electroporation:** an electric pulse opens pores in the membrane (usually of protoplasts). ✓
- **PEG treatment:** polyethylene glycol makes protoplast membranes take up DNA. ✓

**Agrobacterium-mediated transformation** uses a biological vector, the T-DNA from the Ti plasmid, so it is an indirect method. ✗

Answer **A, B and C**.