The PKR regulatory subunit of protein kinase A (PKA) is involved in the regulation of growth, sexual and asexual development, and pathogenesis in Fusarium graminearum

Citations Over TimeTop 10% of 2017 papers

Abstract

Fusarium graminearum is a causal agent of wheat scab disease and a producer of deoxynivalenol (DON) mycotoxins. Treatment with exogenous cyclic adenosine monophosphate (cAMP) increases its DON production. In this study, to better understand the role of the cAMP-protein kinase A (PKA) pathway in F. graminearum, we functionally characterized the PKR gene encoding the regulatory subunit of PKA. Mutants deleted of PKR were viable, but showed severe defects in growth, conidiation and plant infection. The pkr mutant produced compact colonies with shorter aerial hyphae with an increased number of nuclei in hyphal compartments. Mutant conidia were morphologically abnormal and appeared to undergo rapid autophagy-related cell death. The pkr mutant showed blocked perithecium development, but increased DON production. It had a disease index of less than unity and failed to spread to neighbouring spikelets. The mutant was unstable and spontaneous suppressors with a faster growth rate were often produced on older cultures. A total of 67 suppressor strains that grew faster than the original mutant were isolated. Three showed a similar growth rate and colony morphology to the wild-type, but were still defective in conidiation. Sequencing analysis with 18 candidate PKA-related genes in three representative suppressor strains identified mutations only in the CPK1 catalytic subunit gene. Further characterization showed that 10 of the other 64 suppressor strains also had mutations in CPK1. Overall, these results showed that PKR is important for the regulation of hyphal growth, reproduction, pathogenesis and DON production, and mutations in CPK1 are partially suppressive to the deletion of PKR in F. graminearum.

Related Papers

• → Genome‐wide identification of pathogenicity, conidiation and colony sectorization genes in Metarhizium robertsii(2017)39 cited
• → Genetic analysis of conidiation regulatory pathways in koji-mold Aspergillus oryzae(2009)77 cited
• → Aspergillus flavus VelB acts distinctly from VeA in conidiation and may coordinate with FluG to modulate sclerotial production(2013)73 cited
• → Light Represses Conidiation in Koji MoldAspergillus oryzae(2007)29 cited
• → The homeobox gene MaH1 governs microcycle conidiation for increased conidial yield by mediating transcription of conidiation pattern shift-related genes in Metarhizium acridum(2019)14 cited