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A Novel Partitivirus Orchestrates Conidiation, Stress Response, Pathogenicity, and Secondary Metabolism of the Entomopathogenic Fungus Metarhizium majus

Summary

This research discovered a new virus that infects and alters the behavior of an insect-killing fungus. The virus makes the fungus less effective at infecting insects and changes how it produces various compounds. This has important implications for understanding how viruses affect fungi and potentially for biological pest control. Impacts on everyday life: – Helps understand how viruses affect beneficial fungi used in agriculture – Could influence development of better biological pesticides – Provides insights into virus-host relationships that could apply to human diseases – May lead to new ways to control harmful fungi – Could help improve production of valuable fungal compounds

Background

Mycoviruses are widely present in fungi but remain understudied in entomopathogenic Metarhizium species. These viruses can affect fungal phenotypes and metabolism, but their impacts on fungal fitness and pathogenicity are not well understood.

Objective

To isolate, characterize and study the effects of a novel double-stranded RNA virus named Metarhizium majus partitivirus 1 (MmPV1) on its fungal host M. majus, particularly examining impacts on conidiation, stress response, pathogenicity and secondary metabolism.

Results

MmPV1 was identified as a new member of the Gammapartitivirus genus with two genomic segments encoding an RNA-dependent RNA polymerase and capsid protein. Virus infection decreased conidiation by over 50%, reduced tolerance to heat shock and UV-B radiation, and attenuated fungal virulence through decreased conidial hydrophobicity, adhesion and cuticular penetration. The virus also significantly altered secondary metabolite production, reducing triterpenoids and metarhizins while increasing nitrogen and phosphorus compounds. Expression of individual viral proteins did not reproduce these effects.

Conclusion

MmPV1 infection decreases M. majus fitness in its environment and reduces its insect-pathogenic capabilities through coordinated effects on conidiation, stress tolerance, pathogenicity, and secondary metabolism. The virus appears to orchestrate these changes through broad effects on host gene expression rather than through individual viral proteins.
  • Published in:PLOS Pathogens,
  • Study Type:Laboratory Research,
  • Source: 10.1371/journal.ppat.1011397
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