The membrane mucin Msb2 regulates aflatoxin biosynthesis and pathogenicity in fungus Aspergillus flavus

• Main Authors: Ling Qin, Ding Li, Jiaru Zhao, Guang Yang, Yinchun Wang, Kunlong Yang, Elisabeth Tumukunde, Shihua Wang, Jun Yuan
• Format: Article
• Language: English
• Published: Wiley 2021-03-01
• Series: Microbial Biotechnology
• Online Access: https://doi.org/10.1111/1751-7915.13701

Summary 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.