Journal
FUNGAL BIOLOGY
Volume 117, Issue 1, Pages 13-21Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.funbio.2012.11.001
Keywords
Cystathionine gamma-synthase; Deoxynivalenol; Fusarium graminearum; Methionine biosynthesis; Virulence
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Funding
- Special Program for Agricultural Research [200903052]
- National Science Foundation [30900954]
- China Agricultural Research System [CARS-3-1-15]
- PCSIRT [IRT0943]
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Methionine (Met) plays an important role in various cellular processes in both eukaryotes and prokaryotes. Cystathionine gamma-synthase encoded by STR2 gene is a key enzyme in Met biosynthesis in Saccharomyces cerevisiae. In this study, we identified FgMETB, a homologue of S. cerevisiae STR2, from Fusarium graminearum using the Protein Basic Local Alignment Search Tool (BLASTP) program. The FgMETB deletion mutants were unable to grow on fructose gelatin agar (FGA) medium containing SO42- as sole sulphur source. In addition, more than 90 % conidia of the mutants were not able to germinate in 2 % sucrose solution within 6 or 12 h of incubation. Supplementation of 1 mM Met or 0.5 mg ml(-1) homocysteine, but not 1 mM cysteine or 0.5 mg ml(-1) glutathione, rescued the defect of mycelial growth and spore germination of FgMETB deletion mutants. These results indicated that the enzyme encoded by FgMETB is involved in conversion of cysteine into homocysteine. Inoculation tests showed that the FgMETB deletion mutant exhibited decreased virulence significantly on wheat heads, which is consistent with a low level of deoxynivalenol (DON) production of the mutant in wheat kernels. Fungicide sensitivity assays revealed FgMETB deletion mutants showed increased sensitivity to the sterol demethylation inhibitor tebuconazole, but did not change their sensitivities to other fungicides. Taken together, results of this study indicated that FgMETB plays a critical role in the regulation of various cellular processes in F. graminearum. (C) 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
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