The transcription factor StuA regulates central carbon metabolism, mycotoxin production, and effector gene expression in the wheat pathogen Stagonospora nodorum.
The Stagonospora nodorum StuA transcription factor gene SnStuA was identified by homology searching in the genome of the wheat pathogen Stagonospora nodorum. Gene expression analysis revealed that SnStuA transcript abundance increased throughout infection and in vitro growth to peak during sporulation. To investigate its role, the gene was deleted by homologous recombination. The growth of the resulting mutants was retarded on glucose compared to the wild-type growth, and the mutants also failed to sporulate. Glutamate as a sole carbon source restored the growth rate defect observed on glucose, although sporulation remained impaired. The SnstuA strains were essentially nonpathogenic, with only minor growth observed around the point of inoculation. The role of SnstuA was investigated using metabolomics, which revealed that this gene's product played a key role in regulating central carbon metabolism, with glycolysis, the TCA cycle, and amino acid synthesis all affected in the mutants. SnStuA was also found to positively regulate the synthesis of the mycotoxin alternariol. Gene expression studies on the recently identified effectors in Stagonospora nodorum found that SnStuA was a positive regulator of SnTox3 but was not required for the expression of ToxA. This study has uncovered a multitude of novel regulatory targets of SnStuA and has highlighted the critical role of this gene product in the pathogenicity of Stagonospora nodorum.
IpCho
Simon V S
SV
Plant Sciences Division, Research School of Biology, Building 46, The Australian National University, Canberra, ACT 0200, Australia.
Tan
Kar-Chun
KC
Koh
Geraldine
G
Gummer
Joel
J
Oliver
Richard P
RP
Trengove
Robert D
RD
Solomon
Peter S
PS
D001203:Ascomycota / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D002244:Carbon / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D009183:Mycotoxins / Q000096:biosynthesis*; D010641:Phenotype; D018515:Plant Leaves / Q000382:microbiology; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014908:Triticum / Q000382:microbiology*
D005656:Fungal Proteins; D009183:Mycotoxins; D014157:Transcription Factors; D002244:Carbon