title: Biocontrol of Rhizoctonia solani damping-off disease in cucumber with Bacillus pumilus SQR-N43.
abstract: Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Micrographs were used to investigate the ability of Bacillus pumilus (B. pumilus) SQR-N43 to control Rhizoctonia solani (R. solani) Q1 in cucumbers. The root colonization ability of B. pumilus SQR-N43 was analyzed in vivo with a green fluorescent protein (GFP) tag. A pot experiment was performed to assess the in vivo disease-control efficiency of B. pumilus SQR-N43 and its bio-organic fertilizer. Results indicate that B. pumilus SQR-N43 induced hyphal deformation, enlargement of cytoplasmic vacuoles and cytoplasmic leakage in R. solani Q1 mycelia. A biofilm on the root surface was formed when the roots were inoculated with 10(7)-10(8)cells g(-1) of soil of GFP-tagged B. pumilus SQR-N43. In the pot experiment, the biocontrol reduced the concentration of R. solani. In contrast to applications of only B. pumilus SQR-N43 (N treatment), which produced control efficiencies of 23%, control efficiencies of 68% were obtained with applications of a fermented organic fertilizer inoculated with B. pumilus SQR-N43 (BIO treatment). After twenty days of incubation, significant differences in the number of CFUs and the percentage of spores of B. pumilus SQR-N43 were recorded between the N treatment (2.20×10(7)CFU g(-1) of soil and 79%, respectively) and the BIO treatment (1.67×10(8)CFU g(-1) of soil and 52%, respectively). The results indicate that B. pumilus SQR-N43 is a potent antagonist against R. solani Q1. The BIO treatment was more effective than the N treatment because it stabilized the population and increased the active form of the antagonist.
authors.affiliation: Jiangsu Key Laboratory for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Xinqi
authors.initials: X
authors.lastname: Huang
authors.forename: Nan
authors.initials: N
authors.lastname: Zhang
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Yong
authors.forename: Xingming
authors.initials: X
authors.lastname: Yang
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
mesh_terms: D000898:Antibiosis; D000935:Antifungal Agents; D001407:Bacillus / Q000502:physiology*; D001685:Biological Factors / Q000096:biosynthesis / Q000378:metabolism; D015169:Colony Count, Microbial; D018553:Cucumis sativus / Q000382:microbiology*; D005308:Fertilizers / Q000382:microbiology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D025301:Hyphae / Q000502:physiology; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology*; D012232:Rhizoctonia / Q000472:pathogenicity / Q000502:physiology*; D012988:Soil Microbiology
chemical_list: D000935:Antifungal Agents; D001685:Biological Factors; D005308:Fertilizers; D049452:Green Fluorescent Proteins