Hypovirulent strains are shown to contain | Agrigyan

• Biological Control via Hypovirulence: Hypovirulence refers to a stable, transmissible reduction in virulence of fungal pathogens, famously observed in the chestnut blight fungus Cryphonectria parasitica.
• Molecular Basis: Hypovirulent strains harbor persistent fungal mycoviruses (family Hypoviridae) that consist of double-stranded RNA (dsRNA) elements residing in the fungal cytoplasm.
• Mechanism: These unencapsidated dsRNA elements suppress fungal expression of virulence factors (such as laccase, oxalic acid, and pheromones), converting aggressive blight strains into benign saprophytic strains that transmit hypovirulence to virulent strains via hyphal anastomosis.
• Conclusion: Hypovirulent strains contain double-stranded RNA elements (Option 2).

Correct option: (2) Double stranded RNA elements