Question

Nucleic acid in majority of the known plant viruses is

• A. ssRNA
• B. dsRNA
• C. ssDNA
• D. dsDNA

Hint:

Unlike animal and bacterial viruses, which frequently have DNA genomes, the vast majority of plant viruses possess single-stranded RNA (ssRNA) genomes, with TMV being the classic example.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Viruses can possess genomes composed of either DNA or RNA, which can be either single-stranded (ss) or double-stranded (ds).
The distribution of these genome types varies across different host kingdoms.

Step 2: Detailed Explanation:
In plant virology, the vast majority (approximately 75% to 80%) of all characterized plant viruses possess single-stranded RNA (ssRNA) genomes.
Furthermore, most of these ssRNA plant viruses possess positive-sense single-stranded RNA (\(+ \text{ssRNA}\)) genomes.
Examples of positive-sense ssRNA plant viruses include the Tobacco Mosaic Virus (TMV), Potato Virus Y, and Cucumber Mosaic Virus.
These viruses can translate their viral proteins directly from the genomic RNA using the host cell's ribosomes upon entry into the cytoplasm.
Double-stranded RNA (dsRNA) (B), single-stranded DNA (ssDNA) (C) (such as Geminiviruses), and double-stranded DNA (dsDNA) (D) (such as Caulimoviruses) represent much smaller fractions of the known plant viral population.
Therefore, single-stranded RNA is the most common genome type in plant viruses.

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