| 摘要 | 第3-5页 |
| Summary | 第5-7页 |
| Abbreviations | 第8-15页 |
| Chapter 1 Introduction | 第15-32页 |
| 1.1 Economic importance of potato | 第15-16页 |
| 1.2 Phytopathogenic fungi attacking potato | 第16-17页 |
| 1.3 Rhizoctonia diseases of potato | 第17-21页 |
| 1.3.1 Rhizoctonia disease cycle and disease symptoms | 第18-19页 |
| 1.3.2 Anastomosis groups of R. solani | 第19-20页 |
| 1.3.3 Epidemiology of R. solani | 第20-21页 |
| 1.4 The management of Rhizoctonia potato disease | 第21-26页 |
| 1.4.1 Biocontrol | 第21-22页 |
| 1.4.2 Cultural practices | 第22-23页 |
| 1.4.3 Chemical control | 第23-24页 |
| 1.4.4 Preformed defense systems | 第24-25页 |
| 1.4.5 Organic matter amendments | 第25-26页 |
| 1.5 Fungal phytotoxins | 第26-29页 |
| 1.5.1 Definitions and chemical structures | 第26-28页 |
| 1.5.2 Phytotoxins from Rhizoctonia solani | 第28-29页 |
| 1.6 Objectives and significance of the study | 第29-32页 |
| Chapter 2 Isolation, purification and characterization of phytotoxins produced byRhizoctonia solani AG-3, the caused agent of potato stem canker | 第32-51页 |
| 2.1 Introduction | 第32-33页 |
| 2.2 Materials and methods | 第33-39页 |
| 2.2.1 Collection of sample | 第33页 |
| 2.2.2 Maintenance and storage of fungal cultures | 第33页 |
| 2.2.3 Culture media | 第33-34页 |
| 2.2.4 Isolation and identification of fungal pathogens | 第34页 |
| 2.2.5 Fungal cultures and toxin production | 第34-35页 |
| 2.2.6 Biological activity and stem canker assay | 第35-36页 |
| 2.2.7 Bioactivity of soluble macromolecular compounds obtained from culturefiltrates | 第36页 |
| 2.2.8 Solvent extraction | 第36页 |
| 2.2.9 Isolation and purification of the phytotoxins from culture filtrates | 第36-37页 |
| 2.2.10 Characterization of purified compound | 第37-38页 |
| 2.2.11 Potato stem canker response to MTPA and MTAA | 第38页 |
| 2.2.12 Statistical analysis | 第38-39页 |
| 2.3 Results | 第39-47页 |
| 2.3.1 Isolation and identification of fungi isolates | 第39页 |
| 2.3.2 Preliminary in vitro characterization | 第39-40页 |
| 2.3.3 Isolation and purification of R. solani toxin | 第40-41页 |
| 2.3.4 Potato stem canker response to toxin fractions | 第41-42页 |
| 2.3.5 IR spectra of the purified compounds | 第42-43页 |
| 2.3.6 HPLC of the purified compounds | 第43-44页 |
| 2.3.7 NMR spectra of the purified compounds | 第44-47页 |
| 2.3.8 Potato stem canker response to MTPA and MTAA | 第47页 |
| 2.4 Discussion | 第47-51页 |
| Chapter 3 Investigation of 3-methylthiopropionic acid of Rhizoctonia solani AG-3 and itsrole in the pathogenicity of the fungus | 第51-67页 |
| 3.1 Introduction | 第51-52页 |
| 3.2 Materials and methods | 第52-56页 |
| 3.2.1 Soil sterilization, source of seed and MTPA | 第52页 |
| 3.2.2 Potato stems canker response to MTPA | 第52页 |
| 3.2.3 Rhizoctonia growth response to MTPA | 第52-53页 |
| 3.2.4 Fungal culture filtrates and toxin production | 第53页 |
| 3.2.5 Bioassay for phytotoxicity | 第53-54页 |
| 3.2.6 Influence of pH on toxin activity | 第54页 |
| 3.2.7 Experimental design | 第54页 |
| 3.2.8 Data collection | 第54-56页 |
| 3.2.9 Statistical analyses | 第56页 |
| 3.3 Results | 第56-64页 |
| 3.3.1 The effect of pH on phytotoxin activity | 第56页 |
| 3.3.2 Plant height, stem diameter, number of stolon and symptomless stolon | 第56-57页 |
| 3.3.3 Canopy development | 第57页 |
| 3.3.4 Effect of MTPA phytotoxin on yield of potato plants | 第57-58页 |
| 3.3.5 Biomass of potato plants | 第58-60页 |
| 3.3.6 Chlorophyll content | 第60页 |
| 3.3.7 Potato seedling root response to MTPA | 第60-62页 |
| 3.3.8 Assessment of disease of potato plants | 第62-64页 |
| 3.4 Discussion | 第64-67页 |
| Chapter 4 Investigation of mechanisms of Rhizoctonia solani phytotoxins in causingpotato stem canker and antioxidant enzyme activities | 第67-86页 |
| 4.1 Introduction | 第67-69页 |
| 4.2 Materials and methods | 第69-73页 |
| 4.2.1 Soil sterilization, potato cultivars, fungal isolates and MTPA | 第69页 |
| 4.2.2 Experimental design and treatment description | 第69-70页 |
| 4.2.3 Data Collected | 第70-71页 |
| 4.2.4 Enzymatic assays | 第71-73页 |
| 4.2.5 Statistical analysis | 第73页 |
| 4.3 Results | 第73-81页 |
| 4.3.1 Soil physicochemical properties | 第73-74页 |
| 4.3.2 Effect of R. solani phytotoxin on stem canker | 第74页 |
| 4.3.3 Influence of R. solani phytotoxin on black scurf of potato | 第74-75页 |
| 4.3.4 Effect of MTPA phytotoxin on MDA content | 第75-76页 |
| 4.3.5 Effect of MTPA phytotoxin on SOD activity | 第76页 |
| 4.3.6 Effect of MTPA phytotoxin on POD activity | 第76-77页 |
| 4.3.7 Effect of MTPA phytotoxin on CAT activity | 第77-78页 |
| 4.3.8 Effect of MTPA phytotoxin on chitinase activity | 第78-79页 |
| 4.3.9 Relationship between the antioxidant enzyme activities and stem canker ofpotato | 第79-81页 |
| 4.4 Discussion | 第81-86页 |
| Chapter 5 General conclusions and future works | 第86-88页 |
| 5.1 General conclusions | 第86-87页 |
| 5.2 Future works | 第87-88页 |
| References | 第88-113页 |
| Acknowledgements | 第113-114页 |
| Personal Resume | 第114页 |
| Publications originating from this dissertation | 第114-115页 |
| Supervisor’s Brief Introduction | 第115-116页 |
