A binary-distributed effector modulates fungal host preference for drosophilids by targeting a lineage-specific...

Area of Science:

• Molecular Biology
• Insect Pathology
• Evolutionary Biology

Background:

• Broad-spectrum fungal pathogens like Beauveria bassiana display host-specific infection patterns.
• Understanding the molecular basis of this host preference is crucial for pathogen control and evolutionary studies.

Purpose of the Study:

• To identify the molecular factors responsible for Beauveria bassiana's host specificity.
• To elucidate the mechanism by which a specific effector influences virulence against Drosophila species.

Main Methods:

• Gene deletion and overexpression of the Bhe1 effector in Beauveria bassiana.
• Protein-protein interaction screening to identify Bhe1 targets.
• RNA interference (RNAi) in Drosophila melanogaster to assess gene function in immunity.
• Analysis of immune factor secretion and Toll pathway involvement.

Main Results:

• The Bhe1 effector is essential for Beauveria bassiana virulence in Drosophila but not in other insect species.
• Bhe1 directly targets and inhibits the function of Dsff1, a Drosophila-specific immune factor regulated by the Toll pathway.
• Dsff1 interacts with Bombardier (Bbd), a Toll-mediated immune factor, and Bhe1 disrupts this interaction, impairing fly antifungal immunity.

Conclusions:

• Bhe1 confers host specificity by interfering with the Drosophila innate immune system via the Dsff1-Bbd pathway.
• This study reveals a novel insect immune factor (Dsff1) and highlights an evolutionary arms race between hosts and parasites.
• The findings provide insights into pathogen virulence mechanisms and insect immune responses.