Question

Given below are two statements:
Statement I : All cellular plant pathogens are culturable
Statement II : None of the non-cellular plant pathogens are culturable
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:

Obligate cellular pathogens (rusts, powdery mildews, phytoplasmas) cannot be cultured in vitro; Non-cellular viruses/viroids are never culturable in cell-free media.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Pathogen culturability in vitro depends on whether the organism is a facultative saprophyte or an obligate biotroph.

Step 2: Detailed Explanation:
1. Statement I is INCORRECT: Many cellular plant pathogens are obligate biotrophs that cannot be cultured on synthetic nutrient agar media in vitro (e.g., rust fungi Puccinia, powdery mildews Erysiphe, downy mildews, plasmodiophorids, and fastidious wall-less phytoplasmas).
2. Statement II is TRUE: Non-cellular infectious biological agents (such as plant viruses and sub-viral viroids) are absolute molecular obligate intracellular parasites that possess no independent cellular metabolic machinery and cannot be cultured on cell-free artificial media.

Step 3: Final Answer:
Therefore, Statement I is incorrect but Statement II is true.