声明
Acknowledgments
Abstract
摘要
Table of Contents
List of Tables
List of Figures
Chapter 1 Introduction
Chapter 2 Literature review
2．1 Bacterial brown stripe disease of rice
2．2 Virulence factors in Acidovorax oryzae
2．2．1 Bacterial surface structures
2．2．2 Bacterial secretion system
2．3 Application of halotolerant bacteria in biocontrol
2．3．1 Halophilic and halotolerant bacteria in hypersaline environments
2．3．2 Potential of halotolerant Bacillus species in biocontrol and promotion of plant growth
2．3．3 Mechanisms involved in growth promotion of plant and biocontrol of halotolerant Bacillus species
2．4 Aspects of nanotechnology in control of plant bacterial disease
2．4．1 Synthesis of silver nanoparticles
2．4．2 Nano-biofertilizer approaches to improve plant health
2．4．3 Nanoparticles-based plant disease management for plant bacterial diseases
2．4．4 Potential mechanism of antimicrobial effects and plant promotion of AgNPs
Chapter 3 Role of type Ⅲ secretion system genes in virulence of rice bacterial brown stripe pathogen Acidovorax oryzae strain RS-2
3．1 Abstract
3．2 Introduction
3．3 Materials and methods
3．3．1 Experimental materials
3．3．2 Routine experimental methods
3．3．3 Prediction of T3SS gene cluster in Ao strain RS-2
3．3．4 Phylogenetic analysis
3．3．6 Construction of T3SS complementation
3．3．7 Seedling pathogenicity of brown stripe bacteria in rice
3．3．8 Determination of bacterial growth
3．3．9 Determination of biofilm formation
3．3．10 Determination of motility
3．3．11 Determination of EPS and extracellular enzyme activities
3．3．12 Detection of bacterial sensitivity to phage
3．3．13 Statistical analysis
3．4．1 In silico identification of T3SS genes
3．4．2 Validation of T3SS genes mutants and complementation
3．4．3 T3SS involved in virulence of Ao strain RS-2 to rice seedlings
3．4．4 T3SS involved in growth of An strain RS-2
3．4．5 T3SS involved in swimming motility of Ao strain RS-2
3．4．6 T3SS involved in biofilm formation of Ao strain RS-2
3．4．7 T3SS involved in production of EPS
3．4．8 T3SS genes did not affect AP1 phage infection and extracellular enzyme production
3．5 Discussion
3．6 Conclusions
Chapter 4 Halotolerant bacteria belonging to operational group Bacillus amyloliquefaciens in biocontrol of the rice bacterial brown stripe pathogen Acidovorax oryzae
4．1 Abstract
4．2 Introduction
4．3 Materials and methods
4．3．1 Bacterial pathogen，growth media and inoculum preparation
4．3．2 Isolation of halotolerant bacteria
4．3．3 In vitro screening for antagonism
4．3．4 In planta screening for antagonism
4．3．5 Bacteriological，physiological and biochemical tests
4．3．6 Fatty acids analysis of halotolerant bacteria
4．3．7 Phylogenetic analyses of 16S rRNA gene sequence
4．3．8 Phylogenetic analyses of gyrA and rpoB gene sequences
4．3．9 Siderophore production of halotolerant bacteria
4．3．10 Lipopeptides detection by MALDI-TOF-MS analysis of halotolerant bacteria
4．3．11 Determination of antibacterial activity of Bacillus culture filtrates
4．3．12 Motility Assays
4．3．14 Transmission electron microscopy analysis
4．3．15 Statistical analysis
4．4 Results
4．4．1 Isolation of halotolerant bacteria
4．4．2 In vitro antagonistic activities against Ao strains
4．4．3 In planta antagonistic activities against Ao strains
4．4．4 Phylogenetic identification based on the 16S rRNA，gyrA，and rpoB genes sequences
4．4．5 Bacteriological，physiological，biochemical，fatty acids characterization and siderophore production
4．4．6 MALDI-TOF identification of lipopeptides of isolates K5-3 and PPB6
4．4．7 Growth inhibition by the metabolites
4．4．8 Inhibition of swimming motility by the metabolites
4．4．9 Inhibition of biofilm formation by the metabolites
4．4．10 Damage of bacterial cells by the metabolites
4．5 Discussion
4．6 Conclusions
Chapter 5 Biogenic synthesis of silver nanoparticles using Phyllanthus emblica fruit extract and its inhibitory effect against the rice bacterial brown stripe pathogen Acidovorax oryzae strain RS-2
5．1 Abstract
5．2 Introduction
5．3 Materials and methods
5．3．1 Materials
5．3．3 Biosynthesis of AgNPs using P．emblica fruit extract
5．3．4 Characterization of the synthesized AgNPs
5．3．5 In vitro antibacterial activity of AgNPs
5．3．6 Minimum inhibitory concentration (MIC) of AgNPs
5．3．7 Effect of contact time of AgNPs on cell survival of Ao strain RS-2
5．3．8 Swarming motility assay
5．3．10 Live／dead cell staining
5．3．11 Transmission electron microscopy (TEM) analysis
5．3．12 Secretion of effectors protein Hcp (hemolysin coregulated protein)
5．3．13 Statistical analysis
5．4 Results
5．4．1 Synthesis and characterization of the synthesized nanoparticles
5．4．2 In vitro antimicrobial activity of AgNPs
5．4．3 Minimum inhibitory concentration (MIC) of AgNPsagainst Ao strain RS-2
5．4．4 Effect of contact time of AgNPs on cell survival of Ao strain RS-2
5．4．5 Swarming motility
5．4．6 Biofilm formation
5．4．7 Live／dead cell staining
5．4．8 Damage of bacterial cells by the synthesized AgNPs
5．4．9 Secretion of effector protein Hcp
5．5 Discussion
5．6 Conclusions
Research Conclusions and Prospects
References
Appendices
List of Publications
