The membrane mucin Msb2 regulates aflatoxin biosynthesis and pathogenicity in fungus Aspergillus flavus
Ling Qin1, Ding Li1, Jiaru Zhao1
1Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Abstract:
As a pathogenic fungus, Aspergillus flavus can produce carcinogenic aflatoxins (AFs), which poses a great threat to crops and animals. Msb2, the signalling mucin protein, is a part of mitogen-activated protein kinase (MAPK) pathway which contributes to a range of physiological processes. In this study, the roles of membrane mucin Msb2 were explored in A. flavus by the application of gene disruption. The deletion of msb2 gene (Δmsb2) caused defects in vegetative growth, sporulation and sclerotia formation when compared to WT and complement strain (Δmsb2C ) in A. flavus. Using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) analysis, it was found that deletion of msb2 down-regulated aflatoxin B1 (AFB1 ) synthesis and decreased the infection capacity of A. flavus. Consistently, Msb2 responds to cell wall stress and osmotic stress by positively regulating the phosphorylation of MAP kinase. Notably, Δmsb2 mutant exhibited cell wall defect, and it was more sensitive to inhibitor caspofungin when compared to WT and Δmsb2C . Taking together, these results revealed that Msb2 plays key roles in morphological development process, stresses adaptation, secondary metabolism and pathogenicity in fungus A. flavus.
Insights
The membrane mucin Msb2 is crucial for Aspergillus flavus growth, aflatoxin production, and pathogenicity. Deleting the Msb2 gene impairs fungal development and stress adaptation, highlighting its role in controlling this crop pathogen.
Area of Science:
- Mycology
- Molecular Biology
- Plant Pathology
Background:
- Aspergillus flavus produces carcinogenic aflatoxins, posing risks to agriculture and animal health.
- The membrane mucin Msb2 is involved in the mitogen-activated protein kinase (MAPK) pathway, regulating fungal physiology.
- Understanding Msb2's function is vital for controlling A. flavus and its toxic byproducts.
Purpose of the Study:
- To investigate the role of the membrane mucin Msb2 in Aspergillus flavus.
- To determine Msb2's contribution to fungal development, stress response, and pathogenicity.
Main Methods:
- Gene disruption to create a Δmsb2 mutant strain.
- Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) for aflatoxin analysis.
- Assessment of growth, sporulation, sclerotia formation, and stress sensitivity.
Main Results:
- Deletion of msb2 resulted in defects in vegetative growth, sporulation, and sclerotia formation.
- The Δmsb2 mutant showed reduced aflatoxin B1 synthesis and decreased infection capacity.
- Msb2 positively regulates MAPK phosphorylation in response to cell wall and osmotic stress, with Δmsb2 mutants exhibiting cell wall defects and increased sensitivity to caspofungin.
Conclusions:
- Msb2 is essential for Aspergillus flavus morphological development, stress adaptation, and secondary metabolism.
- Msb2 plays a significant role in the pathogenicity of A. flavus, making it a potential target for control strategies.
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