Andrew Breakspear,2 and
H. Corby Kistler2,4
1Department of Plant Health and Plant Protection, Bioforsk–Norwegian Institute of Agricultural and Environmental Research, 1432 Ås, Norway; 2Department of Plant Pathology, University of Minnesota, St. Paul 55108, U.S.A.; 3Centre de Recherché Public, Département Environment et Agro-biotechnologies, Gabriel Lippmann, L-4422 Belvaux, Luxembourg 4United States Department of Agriculture–Agricultural Research Service Cereal Disease Laboratory, St. Paul, MN 55108, U.S.A.
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Accepted 21 September 2010.
Fusarium graminearum is an important plant-pathogenic fungus and the major cause of cereal head blight. Here, we report the functional analysis of FgStuA, the gene for a transcription factor with homology to key developmental regulators in fungi. The deletion mutant was greatly reduced in pathogenicity on wheat heads and in production of secondary metabolites. Spore production was significantly impaired in ΔFgStuA, which did not develop perithecia and sexual ascospores, and lacked conidiophores and phialides, leading to delayed production of aberrant macroconidia. FgStuAp appears to act as a global regulator that may affect many diverse aspects of the life cycle of F. graminearum. Transcriptome analysis shows that thousands of genes are differentially expressed in the mutant during asexual sporulation and infection of wheat heads and under conditions that induce secondary metabolites, including many that could account for the mutant phenotypes observed. The primary regulatory targets of FgStuAp are likely genes involved in cell-cycle control, and the predicted FgStuAp sequence has an APSES domain, with homology to helix-loop-helix proteins involved in cell-cycle regulation. The Aspergillus StuAp response element (A/TCGCGT/ANA/C) was found highly enriched in the promoter sequences of cell-cycle genes, which was upregulated in the ΔFgStuA deletion mutant.
© 2011 The American Phytopathological Society