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Updated: Jan 11, 2026
Drosophila melanogaster Larva Injection Protocol
Published on: October 19, 2021
A binary-distributed effector modulates fungal host preference for drosophilids by targeting a lineage-specific
Yujuan Luo1,2, Xinlu Sheng1,3, Dongxiang Wei1,3
1Key Laboratory of Insect Developmental and Evolutionary Biology, State Key Laboratory of Plant Trait Design, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
Abstract:
Unlike host-specific parasites, broad-spectrum pathogens often exhibit an enigmatic strain/race-level preference for infecting particular host species over others. Here, we identify a polymorphic effector (termed Bhe1) that exhibits a binary presence-absence distribution pattern among strains of the entomopathogenic fungus Beauveria bassiana. Gene deletion and overexpression in Bhe1-present strains revealed that this gene functions as a virulence factor against Drosophila species but dispensable for infection of mosquitoes, beetles, and locusts. Through targeted protein screening, we verified that Bhe1 targets a drosophilid-specific factor with an unknown function (termed Dsff1). The expression of Dsff1 is induced in Drosophila melanogaster upon fungal infection and is controlled by the Toll pathway. Survival of Dsff1 RNA interference (RNAi) flies was impaired after infection with the wild-type but not ΔBhe1 strain of B. bassiana. Overexpression of Bhe1 and Dsff1 in D. melanogaster, respectively, suppresses and promotes fly antifungal immunity. Further investigations reveal that Dsff1 binds Bombardier (Bbd), and Bhe1 blocks their interaction. Consistent with Bbd's role as a Toll-mediated immune factor, both Dsff1 and Bbd RNAi flies exhibit similar defects in the secretion of immune factors, including antifungal peptides. While revealing the mechanistic control of parasite host preference, our identification of a novel immune factor in Drosophila underscores a compelling instance of host-parasite evolutionary arms race.
Insights
A novel fungal effector, Bhe1, dictates host specificity in Beauveria bassiana by targeting a Drosophila-specific immune factor, Dsff1. This interaction reveals a key mechanism in host-parasite coevolution and insect immunity.
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.
