Effects of adaptor protein Ste50 on growth, development and pathogenicity of Aspergillus flavus

Abstract:

[Objective] Ste50 is an important adaptor protein in fungi, which plays important roles in signal connection and transmission in multiple MAPK pathways. In this study, Aflste50 protein of Aspergillus flavus was identified and its effects on growth, conidiation, pathogenicity and response to osmotic stress were found. [Methods] Firstly, the ste50 gene was identified in A. flavus NRRL 3357 by bioinformatics method. Then, the effect of gene knockout on growth, secondary metabolite synthesis and stress response of A. flavus were tested. [Results] Compared with the wild type, the growth rate and AFB₁ synthesis of △Aflste50 strain were decreased. And sclerotia formation of A. flavus was blocked when ste50 was absent. At the same time, the pathogenicity to peanut and maize seeds was impaired in △Aflste50. Also, AflSte50 regulated the phosphorylation of MAP kinase under osmotic stress, but did not respond to cell wall stress.[Conclusion] Ste50 (AFLA_ 002340) is an adaptor protein of A. flavus, which affects the growth and development, as well as the synthesis of AFB₁ in this fungus. It can respond to osmotic stress and play a role in the HOG pathway.