title: Bacillus volatiles adversely affect the physiology and ultra-structure of Ralstonia solanacearum and induce systemic resistance in tobacco against bacterial wilt.
abstract: Volatile organic compounds (VOCs) produced by various bacteria have significant potential to enhance plant growth and to control phytopathogens. Six of the most effective antagonistic Bacillus spp. were used in this study against Ralstonia solanacearum (Rsc) TBBS1, the causal agent of bacterial wilt disease in tobacco. Bacillus amyloliquefaciens FZB42 and Bacillus artrophaeus LSSC22 had the strongest inhibitory effect against Rsc. Thirteen VOCs produced by FZB42 and 10 by LSSC22 were identified using gas chromatography-mass spectrometry analysis. Benzaldehyde, 1,2-benzisothiazol-3(2 H)-one and 1,3-butadiene significantly inhibited the colony size, cell viability, and motility of pathogens and negatively influenced chemotaxis. Transmission and scanning electron microscopy revealed severe morphological and ultra-structural changes in cells of Rsc. Furthermore, VOCs altered the transcriptional expression level of PhcA (a global virulence regulator), type III secretion system (T3SS), type IV secretion system (T4SS), extracellular polysaccharides and chemotaxis-related genes, which are major contributors to pathogenicity, resulting in decreased wilt disease. The VOCs significantly up-regulated the expression of genes related to wilt resistance and pathogen defense. Over-expression of EDS1 and NPR1 suggest the involvement of SA pathway in induction of systemic resistance. Our findings provide new insights regarding the potential of antibacterial VOCs as a biocontrol tool against bacterial wilt diseases.
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Hafiz Abdul Samad
authors.initials: HA
authors.lastname: Tahir
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Gu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Yuedi
authors.initials: Y
authors.lastname: Niu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Rong
authors.initials: R
authors.lastname: Huo
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, PR China.
authors.forename: Xuewen
authors.initials: X
authors.lastname: Gao
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001407:Bacillus / Q000737:chemistry*; D002633:Chemotaxis / Q000187:drug effects / Q000235:genetics; D060467:Disease Resistance / Q000187:drug effects; D008401:Gas Chromatography-Mass Spectrometry; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D010935:Plant Diseases / Q000382:microbiology*; D043368:Ralstonia solanacearum / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure*; D014026:Nicotiana / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology*; D014158:Transcription, Genetic / Q000187:drug effects; D014774:Virulence / Q000187:drug effects / Q000235:genetics; D055549:Volatile Organic Compounds / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D055549:Volatile Organic Compounds