Plant virology — Valid systems for cultivating plant viruses include which of the following?

Introduction:
Plant viruses can be propagated in several experimental systems. Recognizing these systems helps in diagnostics, pathogenesis studies, and seed certification testing for virus-free stock.

Given Data / Assumptions:

• Options include explant tissue culture, isolated cell or protoplast systems, and intact plants.
• Each method has specific use-cases based on virus host range and research goals.

Concept / Approach:
Viruses require living cells for replication. Depending on the virus and the desired readout, researchers may inoculate whole plants, use callus or tissue cultures, or infect isolated cells or protoplasts to study replication and movement.

Step-by-Step Solution:

Verification / Alternative check:
Standard plant pathology protocols employ mechanical inoculation on whole plants and protoplast infection for molecular analyses.

Why Other Options Are Wrong:

• Single-method options are incomplete because multiple systems are well established.

Common Pitfalls:
Assuming only intact plants support virus growth; cell-based systems are widely used for controlled experiments.

Final Answer:
All of these