The role of three calcineurin subunits and a related transcription factor (Crz1) in conidiation, multistress tolerance and virulence in Beauveria bassiana
The eukaryotic calcineurin (CN) pathway comprising catalytic A (CnA) and regulatory B subunits (CnB) is crucial for many biological processes but functionally unexplored in entomopathogenic fungi. Here, we characterise three CN subunits (CnA1, CnA2 and CnB) and a downstream CN-responsive zinc finger...
Saved in:
Published in | Applied microbiology and biotechnology Vol. 99; no. 2; pp. 827 - 840 |
---|---|
Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.01.2015
Springer Springer Nature B.V |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | The eukaryotic calcineurin (CN) pathway comprising catalytic A (CnA) and regulatory B subunits (CnB) is crucial for many biological processes but functionally unexplored in entomopathogenic fungi. Here, we characterise three CN subunits (CnA1, CnA2 and CnB) and a downstream CN-responsive zinc finger transcription factor (Crz1) in
Beauveria bassiana
. CN-mediated phosphatase activity decreased by 16–38 % in all deletion mutants compared with wild type. Growth and conidiation were most defective in Δ
cnB
, which showed a large proportion of abnormally branched germlings but were less defective in Δ
cnA1
and Δ
cnA2
. Conidiation defects also occurred in Δ
crz1
, uniquely accompanied with slower germination. Compared with wild type, the four deletion mutants became, to varying degrees, more sensitive to Ca
2+
, Mn
2+
, Zn
2+
, Mg
2+
, two oxidants, three cell wall stressors, carbendazim, heat shock and ultraviolet (UV)-B irradiation. They were also less virulent to
Spodoptera litura
larvae. Only Δ
cnB
and Δ
crz1
were less tolerant to high osmolarity. The altered phenotypes of the deletion mutants were associated with lower intracellular mannitol and trehalose levels, reduced overall activity of superoxide dismutases and catalases, altered cell wall composition and down-regulation of numerous phenotype-influencing genes. Additionally, the transcription of six cascaded genes in two stress-responsive mitogen-activated protein kinase (MAPK) pathways and the phosphorylation of hallmarking Hog1 and Slt2 were largely down-regulated in all the deletion mutants under osmotic and cell wall stresses, respectively. All the changes were restored by gene complementation. Taken together, three calcineurin subunits and Crz1 play vital, but variable, roles in
B. bassiana
responses to environmental stresses during development and host signals during infection. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0175-7598 1432-0614 |
DOI: | 10.1007/s00253-014-6124-6 |