title: The bacterial lipopeptide iturins induce Verticillium dahliae cell death by affecting fungal signalling pathways and mediate plant defence responses involved in pathogen-associated molecular pattern-triggered immunity.
abstract: Verticillium wilt in cotton caused by Verticillium dahliae is one of the most serious plant diseases worldwide. Because no known fungicides or cotton cultivars provide sufficient protection against this pathogen, V. dahliae causes major crop yield losses. Here, an isolated cotton endophytic bacterium, designated Bacillus amyloliquefaciens 41B-1, exhibited greater than 50% biocontrol efficacy against V. dahliae in cotton plants under greenhouse conditions. Through high-performance liquid chromatography and mass analysis of the filtrate, we found that the antifungal compounds present in the strain 41B-1 culture filtrate were a series of isoforms of iturins. The purified iturins suppressed V. dahliae microsclerotial germination in the absence or presence of cotton. Treatment with the iturins induced reactive oxygen species bursts, Hog1 mitogen-activated protein kinase (MAPK) activation and defects in cell wall integrity. The oxidative stress response and high-osmolarity glycerol pathway contribute to iturins resistance in V. dahliae. In contrast, the Slt2 MAPK pathway may be involved in iturins sensitivity in this fungus. In addition to antagonism, iturins could induce plant defence responses as activators and mediate pathogen-associated molecular pattern-triggered immunity. These findings suggest that iturins may affect fungal signalling pathways and mediate plant defence responses against V. dahliae.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Han
authors.forename: Fengli
authors.initials: F
authors.lastname: Wu
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Qi
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.forename: Ang
authors.initials: A
authors.lastname: Ren
authors.forename: Qinghai
authors.initials: Q
authors.lastname: Liu
authors.forename: Mingwen
authors.initials: M
authors.lastname: Zhao
authors.forename: Canming
authors.initials: C
authors.lastname: Tang
mesh_terms: D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology*; D001407:Bacillus / Q000378:metabolism; D002473:Cell Wall / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D003368:Gossypium / Q000276:immunology / Q000382:microbiology*; D055666:Lipopeptides / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D020172:Verticillium / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D055666:Lipopeptides; D010456:Peptides, Cyclic; D012336:RNA, Ribosomal, 16S; D017382:Reactive Oxygen Species; C013579:iturin A; C033468:iturin C; D020928:Mitogen-Activated Protein Kinases