GATE BT 2024 • Q47
MSQ • 2 Marks
Section 2: General Biotechnology
Cell structure and signaling
Subtopic: Fundamentals of Cell structure and signaling
Question Statement:
Which of the following is/are considered as biotic elicitor(s) in plant cell culture?
Options:
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(A) Cellulase
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(B) Chitin
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(C) Chitosan
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(D) Mercuric chloride
Official Answer Key:
A;B;C
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2024 Q.47)**
**1. Governing Concept**:
- **Topic**: Plant Cell Culture & Elicitation of Secondary Metabolites
- **Elicitors** are compounds that stimulate plant defense responses and elevate secondary metabolite biosynthesis:
- **Biotic Elicitors**: Derived from biological origins (pathogens, fungi, bacteria, yeasts, or plant cell walls):
- Fungal mycelium extracts, fungal cell wall fragments (e.g. Chitosan, Chitin, Glucans).
- Yeast extract.
- Pectins and oligogalacturonides released from plant walls.
- **Abiotic Elicitors**: Physical or non-biological chemical factors (e.g. UV radiation, heavy metal ions like $\text{Cd}^{2+}$, $\text{Cu}^{2+}$, osmotic stress, temperature extremes).
**2. Option Analysis**:
- **Option (A) [Yeast extract] is CORRECT**: A classic biotic elicitor complex composed of fungal/yeast cell wall components and peptides.
- **Option (B) [Chitosan] is CORRECT**: Deacetylated chitin derived from fungal or crustacean cell walls; a potent biotic elicitor.
- **Option (C) [Fungal cell wall fragments] is CORRECT**: Pathogen-associated molecular patterns (PAMPs) that trigger phytoalexin accumulation.
- **Option (D) [Heavy metal ions] is INCORRECT**: Heavy metals ($\text{Cu}^{2+}, \text{Cd}^{2+}$) are abiotic (chemical/physical) elicitors.
**3. Final Answer**:
- **Correct Options**: **A, B, C**
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