Question

Given below are two statements:
Statement I : In cytoplasmic genetic male sterility system, the R line is used to produce hybrid seeds
Statement II : In cytoplasmic genetic male sterility system, A and B lines are crossed to produce B line only
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is correct but Statement II is false
• D. Statement I is incorrect but Statement II is true

Hint:

CGMS three-line system: $A \times B \to A\,\text{line}$ (maintenance); $A \times R \to F_1\,\text{hybrid}$ (commercial hybrid seed); $B$ and $R$ lines maintained by selfing.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The three-line CGMS system (A-line, B-line, and R-line) is used for commercial hybrid seed production in pearl millet, rice, and sorghum.

Step 2: Detailed Explanation:
1. Statement I is TRUE: In commercial $F_1$ hybrid seed production, the male-sterile female parent (A-line, sterile cytoplasm with recessive maintainer alleles) is pollinated by the Restorer line (R-line, carrying dominant nuclear fertility restorer gene $Rf$) to produce fully fertile $F_1$ hybrid seeds ($A \times R \to F_1$ hybrid).
2. Statement II is FALSE: Crossing the A-line with the isogenic B-line (maintainer line) ($A \times B$) produces male-sterile A-line seeds (for A-line seed maintenance), not B-line seeds (B-line is maintained by selfing).

Step 3: Final Answer:
Therefore, Statement I is correct but Statement II is false.