Question:
Assertion (A): The gene that encodes for Barnase is used to induce male sterility in transgenic plants.
Reason (R): Barnase is a RNA hydrolyzing enzyme that inhibits pollen formation in the tapetal cells of anther.
Assertion (A): The gene that encodes for Barnase is used to induce male sterility in transgenic plants.
Reason (R): Barnase is a RNA hydrolyzing enzyme that inhibits pollen formation in the tapetal cells of anther.
Reason (R): Barnase is a RNA hydrolyzing enzyme that inhibits pollen formation in the tapetal cells of anther.
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To restore fertility in the F1 hybrid seeds, the male-sterile barnase plant is crossed with a male plant expressing the Barstar gene (also from B. amyloliquefaciens), which encodes a specific inhibitor of the Barnase ribonuclease.
Updated On: Jun 19, 2026
- Both Assertion (A) and Reason (R) are true and the Reason (R) is the correct explanation of the Assertion (A).
- Both Assertion (A) and Reason (R) are true, but the Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.
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The Correct Option is A
Solution and Explanation
Step 1: Evaluating the Assertion (A)
In hybrid seed production, preventing self-pollination is essential. To achieve this, genetic engineering uses the barnase gene (isolated from Bacillus amyloliquefaciens) to induce male sterility in crops like mustard. Thus, Assertion (A) is true.
Step 2: Evaluating the Reason (R)
The barnase gene encodes a highly active ribonuclease (RNA hydrolyzing enzyme). In transgenic plants, this gene is placed under the control of a tapetum-specific promoter (TA29). As a result, the enzyme is expressed selectively in the tapetal layer of the anther during pollen development. The ribonuclease degrades cellular RNA in these nutritive cells, causing them to degenerate and arresting pollen grain development, which results in male sterility. Thus, Reason (R) is true.
Step 3: Logical Connection
The ribonuclease activity of Barnase within the tapetal cells (Reason) explains exactly how the gene induces male sterility in transgenic plants (Assertion).
Step 4: Conclusion
Both A and R are true, and R is the correct explanation of A, matching option (A). Final Answer: (A)
In hybrid seed production, preventing self-pollination is essential. To achieve this, genetic engineering uses the barnase gene (isolated from Bacillus amyloliquefaciens) to induce male sterility in crops like mustard. Thus, Assertion (A) is true.
Step 2: Evaluating the Reason (R)
The barnase gene encodes a highly active ribonuclease (RNA hydrolyzing enzyme). In transgenic plants, this gene is placed under the control of a tapetum-specific promoter (TA29). As a result, the enzyme is expressed selectively in the tapetal layer of the anther during pollen development. The ribonuclease degrades cellular RNA in these nutritive cells, causing them to degenerate and arresting pollen grain development, which results in male sterility. Thus, Reason (R) is true.
Step 3: Logical Connection
The ribonuclease activity of Barnase within the tapetal cells (Reason) explains exactly how the gene induces male sterility in transgenic plants (Assertion).
Step 4: Conclusion
Both A and R are true, and R is the correct explanation of A, matching option (A). Final Answer: (A)
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