Question:
Which one of the following is NOT a component of heat stress tolerance in crop plants ?
Which one of the following is NOT a component of heat stress tolerance in crop plants ?
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The Cell Membrane Thermostability (CMS) test, which measures electrolyte leakage after heat exposure, is a widely used laboratory screening method to evaluate heat tolerance in crop breeding programs.
Updated On: Jul 23, 2026
- Membrane stability
- Photosynthate translocation
- Osmoregulation
- Enhanced heat sensitivity of photosystem-II
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
Heat stress tolerance describes a plant's ability to maintain growth, cellular function, and productivity under high temperature conditions.
Plants use various physiological, biochemical, and structural adaptations to tolerate heat stress.
Step 2: Detailed Explanation:
Let us analyze the physiological components of heat stress tolerance:
- Membrane stability (A): High temperatures can fluidize and damage cell membranes, causing electrolyte leakage.
Maintaining membrane stability by modifying lipid composition is a key component of heat tolerance.
- Photosynthate translocation (B): Heat stress can damage the vascular system and slow down the transport of sugars.
Tolerance requires maintaining efficient translocation of photosynthates from source leaves to sink tissues (such as grain or fruit).
- Osmoregulation (C): Accumulating compatible solutes (like proline and glycine betaine) helps maintain cell turgor and protects proteins from heat denaturation.
- Photosystem-II (PS-II): PS-II is the most heat-sensitive component of the photosynthetic apparatus.
High temperatures damage the oxygen-evolving complex and the reaction center of PS-II, inhibiting photosynthesis.
Therefore, heat tolerance requires reduced heat sensitivity (enhanced thermal stability) of PS-II, rather than enhanced heat sensitivity.
Thus, option (D) is not a component of heat tolerance.
Step 3: Final Answer:
Enhanced heat sensitivity of photosystem-II is not a component of heat stress tolerance, corresponding to option (D).
Heat stress tolerance describes a plant's ability to maintain growth, cellular function, and productivity under high temperature conditions.
Plants use various physiological, biochemical, and structural adaptations to tolerate heat stress.
Step 2: Detailed Explanation:
Let us analyze the physiological components of heat stress tolerance:
- Membrane stability (A): High temperatures can fluidize and damage cell membranes, causing electrolyte leakage.
Maintaining membrane stability by modifying lipid composition is a key component of heat tolerance.
- Photosynthate translocation (B): Heat stress can damage the vascular system and slow down the transport of sugars.
Tolerance requires maintaining efficient translocation of photosynthates from source leaves to sink tissues (such as grain or fruit).
- Osmoregulation (C): Accumulating compatible solutes (like proline and glycine betaine) helps maintain cell turgor and protects proteins from heat denaturation.
- Photosystem-II (PS-II): PS-II is the most heat-sensitive component of the photosynthetic apparatus.
High temperatures damage the oxygen-evolving complex and the reaction center of PS-II, inhibiting photosynthesis.
Therefore, heat tolerance requires reduced heat sensitivity (enhanced thermal stability) of PS-II, rather than enhanced heat sensitivity.
Thus, option (D) is not a component of heat tolerance.
Step 3: Final Answer:
Enhanced heat sensitivity of photosystem-II is not a component of heat stress tolerance, corresponding to option (D).
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