Q.16 Which one of the following is NOT a protoplast fusion inducing agent?
(A) Inactivated Sendai virus (B) Ca2+ at alkaline pH
(C) Polyethylene glycol (D) Colchicine
Protoplast fusion merges plant cells without walls to create somatic hybrids, bypassing sexual incompatibility for novel traits like disease resistance. Common chemical and viral agents destabilize membranes to promote fusion in bioengineering. Colchicine stands apart as it disrupts microtubules, not fusion directly.
Correct Answer
Colchicine (D) fails as a protoplast fusion inducer. This alkaloid binds tubulin, inhibiting spindle formation during mitosis and preventing chromosome segregation—useful for polyploidy induction but irrelevant to membrane fusion mechanics. True inducers target electrostatic repulsion and lipid mixing between protoplasts.
Option Explanations
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Inactivated Sendai virus (A): Viral fusion proteins (F and HN) bridge and merge protoplast membranes; early mammalian cell fusion method adapted for plants despite lower efficiency.
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Ca2+ at alkaline pH (B): High pH neutralizes surface charge, while Ca²⁺ bridges negative phospholipids, promoting agglutination and fusion; often combined with PEG for synergy.
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Polyethylene glycol (C): PEG (MW 1540-6000) dehydrates plasma membranes, removing water barriers to induce close contact and lipid mixing; most widely used chemical fusogen at 25-50% concentrations.
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Colchicine (D): Microtubule poison for colchicine-induced polyploidy via mitosis arrest; no role in protoplast membrane destabilization or fusion.
Applications in Biotechnology
PEG-driven fusions produce hybrids like pomato (potato+tomato) for enzyme production in Jaipur labs, enhancing microbial fermentation strains. This supports SEO-optimized research on somatic hybridization, avoiding colchicine’s mitotic focus for targeted cybrids in crop improvement.
