Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Sweet potato is highly heterozygous with out-breeding habit.
Reason (R): Self-incompatibility is evident in different sweet potato cultivars.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

The hexaploid nature combined with sporophytic self-incompatibility makes sweet potato breeding highly complex, as crossing often results in unpredictable segregation of traits.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Sweet potato (Ipomoea batatas L.) is an auto-hexaploid ($2n = 6x = 90$) crop. Its breeding dynamics are shaped by its genetic complexity and reproductive barriers.

Step 2: Detailed Explanation:
- Assertion (A) is true: Sweet potato exhibits a high degree of heterozygosity, meaning there is significant genetic variation within individual plants. This genetic diversity is maintained by its obligate out-crossing (out-breeding) nature.
- Reason (R) is true: The out-breeding habit of sweet potato is driven by a strong, genetically controlled sporophytic self-incompatibility (SSI) system. This system prevents self-fertilization, ensuring that seeds only form from crosses between compatible, genetically distinct cultivars.
- Relationship: Because the self-incompatibility system (R) is the physiological mechanism that prevents selfing and enforces cross-pollination, it directly explains why sweet potato is highly heterozygous and out-crossing (A). Thus, (R) is the correct explanation of (A).

Step 3: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A).