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Hypovirulence and Double-Stranded RNA in Botrytis cinerea
Phytopathology
|October 24, 2008
Summary
A novel mycovirus, Botrytis cinerea debilitation-related virus (BcDRV), causes hypovirulence in Botrytis cinerea by debilitating pathogenicity and mycelial growth. This double-stranded RNA virus is transmissible and linked to mitochondrial degeneration.
Area of Science:
- Plant Pathology
- Mycology
- Virology
Background:
- Botrytis cinerea is a significant plant pathogen causing considerable crop losses worldwide.
- Hypovirulence, a phenomenon where a pathogen's virulence is reduced, can be associated with viral infections in fungi.
- The role of specific viruses in modulating B. cinerea virulence has not been fully elucidated.
Purpose of the Study:
- To investigate the cause of hypovirulence in a specific strain of Botrytis cinerea (CanBc-1).
- To determine if double-stranded RNA (dsRNA) is associated with reduced pathogenicity and mycelial growth.
- To characterize the nature and transmissibility of the identified dsRNA element.
Main Methods:
- Comparative analysis of B. cinerea strains for pathogenicity on Brassica napus and mycelial growth.
- Detection and characterization of double-stranded RNA (dsRNA) using gel electrophoresis.
- Horizontal transmission experiments to assess the transmissibility of hypovirulence.
- Sequence analysis of dsRNA to identify the associated mycovirus (BcDRV) and its relatives.
- Microscopic examination of hyphal cells to observe cellular changes.
Main Results:
- The B. cinerea strain CanBc-1 exhibited significantly reduced pathogenicity and mycelial growth compared to 20 virulent strains.
- A 3.0 kb dsRNA was detected in the hypovirulent strain CanBc-1 and its hypovirulent single-conidium (SC) isolates, but not in virulent strains.
- The hypovirulent trait was transmissible, and the 3.0-kb dsRNA was implicated in this transmission.
- Sequence analysis identified the dsRNA as a mycovirus, named B. cinerea debilitation-related virus (BcDRV), related to Ophiostoma mitovirus 3b.
- Degeneration of mitochondria and cytoplasm was observed in hyphal cells of the hypovirulent strain.
Conclusions:
- The study reports the first occurrence of Mitovirus-associated hypovirulence in Botrytis cinerea.
- The B. cinerea debilitation-related virus (BcDRV) is responsible for the observed hypovirulence, affecting pathogenicity, growth, and cellular structures.
- BcDRV represents a potential tool for biological control strategies against B. cinerea by reducing its virulence.
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