title: Involvement of a putative response regulator FgRrg-1 in osmotic stress response, fungicide resistance and virulence in Fusarium graminearum.
abstract: Response regulator (RR) proteins are core elements of the high-osmolarity glycerol (HOG) pathway, which plays an important role in the adaptation of fungi to a variety of environmental stresses. In this study, we constructed deletion mutants of two putative RR genes, FgRRG-1 and FgRRG-2, which are orthologues of Neurospora crassa RRG-1 and RRG-2, respectively. The FgRRG-1 deletion mutant (ΔFgRrg1-6) showed increased sensitivity to osmotic stress mediated by NaCl, KCl, sorbitol or glucose, and to metal cations Li(+) , Ca(2+) and Mg(2+) . The mutant, however, was more resistant than the parent isolate to dicarboximide and phenylpyrrole fungicides. Inoculation tests showed that the mutant exhibited decreased virulence on wheat heads. Quantitative real-time polymerase chain reaction assays indicated that the expression of FgOS-2, the putative downstream gene of FgRRG-1, was decreased significantly in ΔFgRrg1-6. All of the defects were restored by genetic complementation of ΔFgRrg1-6 with the wild-type FgRRG-1 gene. Different from the FgRRG-1 deletion mutant, FgRRG-2 deletion mutants were morphologically indistinguishable from the wild-type progenitor in virulence and in sensitivity to the dicarboximide fungicide iprodione and osmotic stresses. These results indicate that the RR FgRrg-1 of F. graminearum is involved in the osmotic stress response, pathogenicity and sensitivity to dicarboximide and phenylpyrrole fungicides and metal cations.
authors.affiliation: Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029, China.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Jiang
authors.forename: Yingzi
authors.initials: Y
authors.lastname: Yun
authors.forename: Jing
authors.initials: J
authors.lastname: Fu
authors.forename: Won-Bo
authors.initials: WB
authors.lastname: Shim
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Ma
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009997:Osmotic Pressure / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013012:Sorbitol / Q000494:pharmacology; D014774:Virulence / Q000187:drug effects / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D012965:Sodium Chloride; D013012:Sorbitol; D011189:Potassium Chloride; D008094:Lithium; D008274:Magnesium; D005947:Glucose; D002118:Calcium