Which of the following is(are) plant protoplast fusogenic agent(s)?
- (A)
Sodium nitrate
- (B)
Polyvinyl alcohol
- (C)
Polyethylene glycol
- (D)
Bromoxynil
GATE 2023 BT Q.43: solution and answer
Answer and solution
ANSWER
The plant protoplast fusogens are sodium nitrate, polyvinyl alcohol and polyethylene glycol: A, B and C.
Official answer: A, B, CSource: Official answer key, GATE 2023 BT (IIT Kanpur)
Protoplast fusion needs a fusogen: an agent that makes the plasma membranes of adjacent protoplasts stick together and merge.
(A) Sodium nitrate is correct. It was one of the earliest chemical fusogens used for plant protoplasts, and it induces fusion.
(B) Polyvinyl alcohol is correct. It is a polymer that promotes protoplast agglutination and fusion, and has been used as a fusogen in plant protoplast work.
(C) Polyethylene glycol is correct. PEG at about 25-30% dehydrates the membranes and bridges adjacent protoplasts, causing fusion. It is the most widely used chemical fusogen, often followed by a high-pH, high- wash.
(D) Bromoxynil is wrong. It is a herbicide that inhibits photosystem II, and it is the basis of the bxn transgene resistance marker. It is not a fusogen.
So the fusogens are sodium nitrate, polyvinyl alcohol and polyethylene glycol: A, B and C.
KEY IDEA
Chemical fusogens for plant protoplasts include sodium nitrate, polyvinyl alcohol, PEG and high-pH, high-Ca2+ solutions. A herbicide used as a selection marker is not a fusogen.
WATCH OUT FOR
Picking only PEG because it is the best known fusogen, or choosing bromoxynil because it appears in plant biotechnology as a herbicide-resistance marker.
From the GATE 2023 BT paper. Every question of this paper · Download the full paper · All 4 Transgenic plants questions, with notes