Question

A. Systemic Acquired Resistance is one of the induced nonspecific resistance systems in plants
B. Induced Systemic Resistance is one of the induced specific resistance systems in plants
C. Hypersensitive Reaction is one of the induced nonspecific resistance systems in plants
D. Hypersensitive Reaction is one of the induced specific resistance systems in plants
E. Induced Systemic Resistance is one of the induced nonspecific resistance systems in plants
Choose the correct answer from the options given below:

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

Hint:

Systemic defenses like SAR and ISR are always nonspecific because they prime the entire plant against a broad spectrum of future pathogens. Localized defenses like the Hypersensitive Reaction (HR) are specific, triggered by gene-for-gene recognition.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Plants have active defense mechanisms that are triggered by pathogens or beneficial microbes.
These defense responses can be specific (directed against a particular pathogen genotype) or nonspecific (conferring broad-spectrum, general resistance).

Step 2: Detailed Explanation:
Let us analyze each statement:
Statement A: Systemic Acquired Resistance (SAR) is induced after local infection by a necrotizing pathogen.
It is mediated by salicylic acid signaling and leads to the expression of pathogenesis-related (PR) proteins. SAR provides long-lasting, broad-spectrum, nonspecific resistance against viruses, bacteria, and fungi. Thus, Statement A is correct.
Statement B & E: Induced Systemic Resistance (ISR) is triggered by beneficial, non-pathogenic rhizobacteria (such as Pseudomonas fluorescens).
It is mediated by jasmonic acid and ethylene signaling pathways. Like SAR, ISR provides broad-spectrum, nonspecific resistance. Thus, Statement E is correct and Statement B is incorrect.
Statement C & D: The Hypersensitive Reaction (HR) is a localized host cell death response triggered by the specific recognition of a pathogen effector by a corresponding host R-gene product (the gene-for-gene model).
Because it relies on this highly specific genetic interaction, HR is an induced specific resistance system. Thus, Statement D is correct and Statement C is incorrect.

Step 3: Final Answer:
Statements A, D, and E are correct, while B and C are incorrect. Therefore, the correct option is (C).