Mid1 affects ion transport, cell wall integrity, and host penetration of the entomopathogenic fungus Metarhizium acridum

  • Mushan Xie
  • Xuan Zhou
  • Yuxian XiaEmail author
  • Yueqing CaoEmail author
Applied genetics and molecular biotechnology


Calcium signaling plays important roles in stress tolerance and virulence in fungi. Mid1, an accessory protein of Cch1 calcium channel, has been discussed in baker’s yeast and some filamentous fungi. However, functions of the Mid1 gene in entomopathogenic fungi are not clear. In this study, the Mid1 gene was functionally characterized by deleting it in the entomopathogenic fungus Metarhizium acridum. The growth of the ΔMaMid1 mutant was similar as the wild type on normal growth medium, but inhibited by exogenous Ca2+, Fe2+, Mg2+, Mn2+, Li+, and calcium chelator ethylene glycol tetraacetic acid (EGTA). Cation transportation-related genes were upregulated and intracellular calcium concentration was decreased in ΔMaMid1. Deletion of the MaMid1 gene impaired the tolerance to cell wall-disrupting agents but had no impact on heat or ultraviolet irradiation tolerance compared with the wild type. Bioassays showed that ΔMaMid1 had decreased virulence, with defects in the ability to penetrate the host cuticle. Compared with the wild type, appressorium formation on locust wings and fungal growth in the insect hemocoel were significantly decreased in the ΔMaMid1 mutant in a bioassay through topical inoculation. The phenotypes of ΔMaMid1 were fully restored in a complementation strain. Taken together, our study demonstrates that the MaMid1 affects intracellular ion homeostasis and contributes to virulence by affecting the initial penetration process in M. acridum.


Entomopathogenic fungi Calcium Mid1 Ion homeostasis Pathogenicity 



This work was supported by the Natural Science Foundation of China (No. 31772222, No. 31371992), Natural Science Foundation Project of CQ CSTC (cstc2018jcyjAX0204).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any studies with human participants performed by any of the authors.

Supplementary material

253_2018_9589_MOESM1_ESM.pdf (828 kb)
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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Life SciencesChongqing UniversityChongqingPeople’s Republic of China
  2. 2.Chongqing Engineering Research Center for Fungal InsecticidesChongqingPeople’s Republic of China
  3. 3.Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education CommissionChongqingChina

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