Question

Match List-I with List-II 

List-I (Virus)		List-II (Genome Type)
A	Beet curly top virus	I	Double-stranded DNA (ds DNA)
B	Tomato spotted wilt virus	II	Positive-sense single-stranded RNA
C	Tobacco mosaic virus	III	Negative-sense single-stranded RNA
D	Cauliflower mosaic virus	IV	Single-stranded DNA (ss DNA)

Choose the correct answer from the options given below:

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (IV), (B) - (III), (C) - (II), (D) - (I)
• (A) - (II), (B) - (I), (C) - (III), (D) - (IV)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)

Hint:

Cauliflower Mosaic Virus (CaMV) is a well-known plant pararetrovirus containing a double-stranded DNA genome. Tobacco Mosaic Virus (TMV) is the classic positive-sense single-stranded RNA virus.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Plant viruses are classified into groups based on their genome type and replication strategy, following the Baltimore classification system.
Detailed Explanation:
Let us match the plant viruses in List I with their genomic characteristics in List II:
- (A) Beet curly top virus (BCTV): This is a Curtovirus within the family Geminiviridae.
Geminiviruses have genomes made of circular, single-stranded DNA (ssDNA) (IV).
- (B) Tomato spotted wilt virus (TSWV): This is an Orthotospovirus within the family Tospoviridae.
It is an enveloped virus with a segmented, tripartite, negative-sense single-stranded RNA (III) genome (with some ambisense segments).
- (C) Tobacco mosaic virus (TMV): This is a Tobamovirus with a rod-shaped virion containing a genome made of linear, positive-sense single-stranded RNA (II).
- (D) Cauliflower mosaic virus (CaMV): This is a pararetrovirus belonging to the family Caulimoviridae.
It replicates via an RNA intermediate but packages a circular, double-stranded DNA (dsDNA) (I) genome.
This yields the match: (A) - (IV), (B) - (III), (C) - (II), (D) - (I).

Step 2: Final Answer:
The correct matching sequence corresponds to option (2).