Q.44 Direct DNA transfer method(s) used for plant genetic engineering is(are)
(A) microparticle bombardment
(B) electroporation
(C) polyethylene glycol treatment
(D) Agrobacterium–mediated transformation

Direct DNA transfer methods for plant genetic engineering include microparticle bombardment, electroporation, and polyethylene glycol treatment, but not Agrobacterium-mediated transformation. The correct answer is A, B, and C. These are physical and chemical techniques that bypass biological vectors.

Option Analysis

Microparticle Bombardment (A) uses a gene gun to shoot DNA-coated gold or tungsten particles into plant cells, penetrating tough cell walls effectively in crops like maize.

Electroporation (B) applies electrical pulses to protoplasts or tissues, creating temporary pores for DNA entry, widely used for monocots and dicots.

Polyethylene Glycol Treatment (C) involves PEG to induce DNA uptake in protoplasts by destabilizing membranes, a simple chemical direct method.

Agrobacterium-mediated (D) relies on bacterial T-DNA transfer, classifying it as vector-mediated, not direct.

Direct DNA transfer methods in plant genetic engineering revolutionize crop improvement by enabling precise gene insertion without biological vectors. These techniques, including microparticle bombardment, electroporation, and polyethylene glycol treatment, target recalcitrant species where Agrobacterium fails.

Microparticle Bombardment Explained

This biolistic method accelerates DNA-coated microprojectiles into plant cells using helium pressure. It suits intact tissues and has produced transgenic cereals like rice and wheat.

Electroporation Mechanism

High-voltage pulses permeabilize protoplast membranes, allowing DNA influx. Optimization of field strength ensures viability and integration, ideal for functional genomics.

PEG Treatment Process

PEG fuses DNA with protoplasts by altering surface charge, yielding stable transformants in tobacco and maize. It requires cell wall removal but offers high throughput.

Comparison Table