title: Antagonistic mechanism of iturin A and plipastatin A from Bacillus amyloliquefaciens S76-3 from wheat spikes against Fusarium graminearum.
abstract: Controlling toxigenic Fusarium graminearum (FG) is challenging. A bacterial strain (S76-3, identified as Bacillus amyloliquefaciens) that was isolated from diseased wheat spikes in the field displayed strong antifungal activity against FG. Reverse-phase high performance liquid chromatography and electrospray ionization mass spectrometry analyses revealed that S76-3 produced three classes of cyclic lipopeptides including iturin, plipastatin and surfactin. Each class consisted of several different molecules. The iturin and plipastatin fractions strongly inhibited FG; the surfactin fractions did not. The most abundant compound that had antagonistic activity from the iturin fraction was iturin A (m/z 1043.35); the most abundant active compound from the plipastatin fraction was plipastatin A (m/z 1463.90). These compounds were analyzed with collision-induced dissociation mass spectrometry. The two purified compounds displayed strong fungicidal activity, completely killing conidial spores at the minimal inhibitory concentration range of 50 µg/ml (iturin A) and 100 µg/ml (plipastatin A). Optical and fluorescence microscopy analyses revealed severe morphological changes in conidia and substantial distortions in FG hyphae treated with iturin A or plipastatin A. Iturin A caused leakage and/or inactivation of FG cellular contents and plipastatin A caused vacuolation. Time-lapse imaging of dynamic antagonistic processes illustrated that iturin A caused distortion and conglobation along hyphae and inhibited branch formation and growth, while plipastatin A caused conglobation in young hyphae and branch tips. Transmission electron microscopy analyses demonstrated that the cell walls of conidia and hyphae of iturin A and plipastatin A treated FG had large gaps and that their plasma membranes were severely damaged and separated from cell walls.
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: An-Dong
authors.initials: AD
authors.lastname: Gong
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Li
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Qing-Song
authors.initials: QS
authors.lastname: Yuan
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Xiu-Shi
authors.initials: XS
authors.lastname: Song
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yao
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Wei-Jie
authors.initials: WJ
authors.lastname: He
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Jing-Bo
authors.initials: JB
authors.lastname: Zhang
authors.affiliation: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Yu-Cai
authors.initials: YC
authors.lastname: Liao
mesh_terms: D000595:Amino Acid Sequence; D000898:Antibiosis; D001407:Bacillus / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D005670:Fusarium / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology; D014908:Triticum / Q000382:microbiology*
chemical_list: D005227:Fatty Acids; D009842:Oligopeptides; D010456:Peptides, Cyclic; C049901:plipastatin; C013579:iturin A