Question

Vertical resistance is:
A. Also know as race specific resistance
B. More durable
C. Qualitative resistance
D. Influenced by the environment
Choose the correct answer from the options given below:

• A. A and B only
• B. A and C only
• C. B and C only
• D. C and D only

Hint:

To distinguish between resistance types:
- Vertical = Monogenic, Qualitative, Race-Specific, Less Durable.
- Horizontal = Polygenic, Quantitative, Race-Non-specific, Highly Durable.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In plant breeding and pathology, disease resistance in crops is classified into two types: vertical resistance and horizontal resistance.
- Vertical Resistance: Controlled by one or a few major genes (monogenic or oligogenic) and is effective against specific races of a pathogen.
- Horizontal Resistance: Controlled by multiple minor genes (polygenic) and is effective against all races of a pathogen.

Step 2: Detailed Explanation:
Let us analyze the statements provided:
- Statement A: Vertical resistance is also known as race-specific resistance because a crop variety is highly resistant to specific races of a pathogen but susceptible to others. This statement is correct.
- Statement B: Vertical resistance is generally not durable. Because it relies on a single major gene, a single mutation in the pathogen can overcome the host plant's defenses, leading to a sudden breakdown of resistance in the field. This statement is incorrect.
- Statement C: It is classified as qualitative resistance because the host reaction shows clear, distinct categories of response (either completely resistant or completely susceptible). This statement is correct.
- Statement D: Vertical resistance is highly stable under varying weather conditions and is less influenced by the environment compared to horizontal resistance. This statement is incorrect.
Therefore, only statements A and C are correct.

Step 3: Final Answer:
The correct option is (B).