Engineering virus resistance in plants: which genetic strategies have been used to create resistance against plant viral infections?
-
AExpression of viral capsid (coat) protein genes
-
BExpression of viral nucleocapsid or movement protein genes
-
CUse of satellite RNA sequences that interfere with helper viruses
-
DAll of these
-
EOnly RNA interference works; these do not
Answer
Correct Answer: All of these
Explanation
Introduction / Context:Transgenic strategies for plant virus resistance predate RNA interference and include “pathogen-derived resistance.” By expressing viral components in the plant, replication or movement of the invading virus can be impaired.
Given Data / Assumptions:
- Coat protein–mediated resistance can block uncoating or assembly dynamics.
- Movement/nucleocapsid proteins can interfere with cell-to-cell or systemic spread.
- Satellite RNAs can attenuate symptom development with certain helper viruses.
Concept / Approach:Each approach exploits molecular interference. Coat protein expression often yields broad resistance to related strains. Movement/nucleocapsid protein expression can disrupt trafficking. Satellite RNA can modulate pathogenicity by competing for replication machinery.
Step-by-Step Solution:
List known, published strategies: CP, MP/NP, and satellite RNA.Assess mechanism: interference with viral life cycle stages.Select the comprehensive option including all three.Verification / Alternative check:Classic examples include coat-protein-mediated resistance in tobacco and squash, and satellite RNA approaches against Cucumber mosaic virus.
Why Other Options Are Wrong:
- A/B/C alone are incomplete.
- E is incorrect; RNAi is powerful but not the only method historically or currently used.
Common Pitfalls:Assuming a single universal mechanism; efficacy is virus- and host-dependent.
Final Answer:All of these