title: Study on screening and antagonistic mechanisms of Bacillus amyloliquefaciens 54 against bacterial fruit blotch (BFB) caused by Acidovorax avenae subsp. citrulli.
abstract: Bacterial fruit blotch (BFB) was a serious threat to cucurbitaceae crops. It was caused by the gram-negative bacterium Acidovorax avenae subsp. citrulli. Two hundred strains, which have the potential in controlling plant diseases in our laboratory's biocontrol strain library, were employed to this research to screen some antagonistic bacteria, which can efficiently control bacterial fruit blotch disease. Based on the results of antagonistic activity experiments, greenhouse tests and field trials, 5 of the test strains have high abilities to control BFB. One of the 5 bacteria strains has the highest potential to control BFB named 54. The biocontrol efficacy of 54 was up to 60%. To characterize the strain, we used series of methods to evaluate the bacterium, including morphology analysis, physiological biochemical test and biomolecular assay. We found that the bacterium 54 belongs to the species Bacillus amyloliquefaciens. The colonization test results showed that 54 had the highest colonization levels, and the density of the strain on leaves was up 10(5)colony forming units (CFU) per gram of leaf tissue. Our recent results show that B. amyloliquefaciens 54 can promote the plant growth due to raised the contents of available N, P, K and the leaf chlorophyll. The antagonistic bacterium 54 can significantly control the BF B by increasing the expression level of defense-related gene PR1 and the accumulation the hydrogen peroxide in the plant. The results of trail experiment was also verified this efficient results of bacterium. This is also the first report of B. amyloliquefaciens strain that is able to control BFB.
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Chun-Hao
authors.initials: CH
authors.lastname: Jiang
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Zhen-Yun
authors.initials: ZY
authors.lastname: Yu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xie
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Hong-Jiao
authors.initials: HJ
authors.lastname: Ke
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Li
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Yi-Yang
authors.initials: YY
authors.lastname: Yu
authors.affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China. Electronic address: jhguo@njau.edu.cn.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Guo
mesh_terms: D000898:Antibiosis; D001407:Bacillus; D061046:Biological Control Agents; D042621:Comamonadaceae; D015870:Gene Expression; D006861:Hydrogen Peroxide / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology
chemical_list: D061046:Biological Control Agents; D006861:Hydrogen Peroxide
keywords: Bacillus amyloliquefaciens; Bacterial fruit blotch (BFB); Biocontrol efficiency; Hydrogen peroxide accumulation; Plant growth promotion