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Published on: February 8, 2019
The Magas1 gene is involved in pathogenesis by affecting penetration in Metarhizium acridum
Yueqing Cao1, Xiangxian Zhu, Run Jiao
1Genetic Engineering Research Center, College of Bioengineering, Chongqing University, Chongqing Engineering Research Center for Fungal Insecticides and Key Laboratory of Functional Gene and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing, 400030, P.R. China.
Abstract:
Appressorium is a specialized infection structure of filamentous pathogenic fungi and plays an important role in establishing a pathogenic relationship with the host. The Egh16/Egh16H family members are involved in appressorium formation and pathogenesis in pathogenic filamentous fungi. In this study, a homolog of Egh16H, Magas1, was identified from an entomopathogenic fungus, Metarhizium acridum. The Magas1 protein shared a number of conserved motifs with other Egh16/Egh16H family members and specifically expressed during the appressorium development period. Magas1-EGFP fusion expression showed that Magas1 protein was not localized inside the cell. Deletion of the Magas1 gene had no impact on vegetative growth, conidiation and appressorium formation, but resulted in a decreased mortality of host insect when topically inoculated. However, the mortality was not significant between the Magas1 deletion mutant and wild-type treatment when the cuticle was bypassed by injecting conidia directly into the hemocoel. Our results suggested that Magas1 may influence virulence by affecting the penetration of the insects' cuticle.
Insights
Researchers identified Magas1 in Metarhizium acridum, a protein involved in fungal infection. While not affecting fungal growth or appressorium formation, Magas1 impacts insect cuticle penetration, influencing fungal virulence.
Area of Science:
- Mycology
- Plant Pathology
- Insect Pathology
Background:
- Appressorium formation is crucial for filamentous fungal pathogens to infect hosts.
- The Egh16/Egh16H protein family is known to be involved in appressorium development and pathogenesis.
Purpose of the Study:
- To identify and characterize a novel homolog of Egh16H in the entomopathogenic fungus Metarhizium acridum.
- To investigate the role of this homolog, named Magas1, in fungal virulence and host infection.
Main Methods:
- Identification and sequence analysis of Magas1 in Metarhizium acridum.
- Gene deletion mutant construction and phenotypic analysis (vegetative growth, conidiation, appressorium formation).
- Virulence assays on host insects via topical inoculation and hemocoel injection, with and without cuticle penetration.
Main Results:
- Magas1 shares conserved motifs with Egh16/Egh16H family members and is specifically expressed during appressorium development.
- Magas1 protein is not localized intracellularly.
- Deletion of Magas1 did not affect fungal growth, sporulation, or appressorium formation.
- Magas1 deletion mutants showed reduced insect mortality after topical inoculation but not after hemocoel injection.
Conclusions:
- Magas1 plays a role in the virulence of Metarhizium acridum.
- The Magas1 protein appears to be involved in facilitating the penetration of the insect cuticle, rather than in initial infection structure formation or growth.
