An Asp f2-like protein negatively affects stress tolerance, conidiation and virulence in Metarhizium acridum
Geng Hong1, Shanjun Wang1, Yumei Jin1
1School of Life Sciences, Chongqing University, Chongqing 401331, China; Chongqing Engineering Research Center for Fungal Insecticides, Chongqing 401331, China; Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing, China.
Abstract:
Metarhizium acridum is a typical filamentous fungus that has been widely used to control grasshoppers, locusts, and crickets. Genetic engineering is a common strategy to enhance its virulence, conidiation, and stress tolerance. Here, we report that the M. acridum Asp f2-like protein (MaAL) plays key roles in virulence, conidiation, and stress tolerance. Disruption of MaAL (ΔMaAL) resulted in faster conidial germination and significantly increased conidial yield. The conidial yield of the ΔMaAL strain was 113.33 % higher than that of the wild-type (WT) strain. The ΔMaAL strain exhibited significantly enhanced tolerance to UV-B irradiation, heat shock, and high osmotic stress. Furthermore, both topical inoculation and intra-hemocoel injection demonstrated significantly increased virulence against Locusta migratoria. Specifically, the LT50 of ΔMaAL was reduced by 1.54 days for topical inoculation and 1.08 days for intra-hemocoel injection compare to WT. Further investigation revealed that the deletion of MaAL led to increased turgor pressure in appressoria, reduced immune responses in locusts, and faster hyphal growth in the hemolymph. This study explores the function of Asp f2-like proteins in entomopathogenic fungi, providing theoretical support and genetic resources for the development of high-virulence strains.
Insights
Disrupting the MaAL protein in Metarhizium acridum significantly boosted fungal virulence and stress tolerance. This genetic modification enhances conidial yield and improves control of locust pests.
Area of Science:
- Mycology
- Entomology
- Biotechnology
Background:
- Metarhizium acridum is a key fungal agent for controlling insect pests like locusts.
- Genetic engineering aims to improve fungal biocontrol agents' efficacy.
- Asp f2-like proteins are implicated in fungal functions, but their specific roles in M. acridum require elucidation.
Purpose of the Study:
- To investigate the function of the M. acridum Asp f2-like protein (MaAL) in virulence, conidiation, and stress tolerance.
- To assess the impact of MaAL disruption on M. acridum's biocontrol capabilities.
- To provide genetic resources for developing enhanced fungal biocontrol strains.
Main Methods:
- Gene disruption of MaAL in M. acridum to create a knockout strain (ΔMaAL).
- Quantification of conidial yield and germination rates.
- Assessment of tolerance to UV-B, heat shock, and osmotic stress.
- Virulence assays against Locusta migratoria using topical and intra-hemocoel inoculation.
- Analysis of appressorial turgor pressure, locust immune response, and hyphal growth rate.
Main Results:
- The ΔMaAL strain showed a 113.33% increase in conidial yield and faster germination.
- ΔMaAL exhibited enhanced tolerance to UV-B, heat shock, and osmotic stress.
- Virulence against Locusta migratoria was significantly increased, with reduced LT50 values.
- MaAL deletion led to increased appressorial turgor pressure, reduced locust immunity, and faster hemolymph growth.
Conclusions:
- MaAL plays a crucial role in regulating virulence, conidiation, and stress tolerance in M. acridum.
- Disruption of MaAL enhances the fungus's potential as a biocontrol agent against locusts.
- This research offers valuable insights into Asp f2-like protein function and provides tools for developing superior entomopathogenic fungal strains.
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