| 摘要 | 第5-7页 |
| Abstract | 第7-8页 |
| 1. Background | 第12-36页 |
| 1.1 Heat stress | 第12-21页 |
| 1.1.1 Effects of heat stress on the plants | 第12-13页 |
| 1.1.2 The roles of ROS during plant heat stress responses | 第13-19页 |
| 1.1.3 Adaptation mechanisms of plants to hightemperature | 第19-21页 |
| 1.1.4 Effects of exogenous compounds on plant heat stress responses | 第21页 |
| 1.2 Drought stress | 第21-23页 |
| 1.3 Melatonin | 第23-29页 |
| 1.3.1 Functions of melatonin | 第24-25页 |
| 1.3.2 Biosynthesis of melatonin | 第25-28页 |
| 1.3.3 The roles of melatonin | 第28-29页 |
| 1.4 2,4-Epibrassinolide | 第29-33页 |
| 1.4.1 Functions of brassinosteroids | 第30-31页 |
| 1.4.2 The roles of 2,4-epibrassinolide/brassinosteroids | 第31-33页 |
| 1.5 Tall fescue | 第33-36页 |
| 2. Chapter OneTranscriptomis profiling of tall fescue in response to heat stress andimproved thermotolerance by melatonin and 2,4 epibrasnolide | 第36-64页 |
| 2.1 Introduction | 第36-38页 |
| 2.1.1 Objectives, purposes and content research | 第36-38页 |
| 2.2 Materials and Methods | 第38-42页 |
| 2.2.1 Plant material and growth conditions | 第38页 |
| 2.2.2 Chemicals, treatments and experimental design | 第38页 |
| 2.2.3 Measurement of fresh weight and plant height of tall fescue | 第38页 |
| 2.2.4 Quantification of reactive oxygen species,antioxidantenzymes and protein content | 第38-39页 |
| 2.2.5 Measurement of malondialdehyde and electrolyte leakage | 第39页 |
| 2.2.6 Measurement of chlorophyll | 第39-40页 |
| 2.2.7 RNA sequencing analysis | 第40页 |
| 2.2.8 Gene ontology (GO)term and pathway enrichment and clusteranalyses | 第40-41页 |
| 2.2.9 Quantitative real-time-polymerasc chain reaction (qRT-PCR) | 第41页 |
| 2.2.10 Statistical analysis | 第41-42页 |
| 2.3 Result | 第42-60页 |
| 2.3.1 Effects of MT and EBL on the plant growth under heatstress | 第42-43页 |
| 2.3.2 Effects of MT and EBL on electrolyte leakage, chlorophyll andtotal protein content under heat tress | 第43-45页 |
| 2.3.3 Effects of MT and EBL on ROS and cell membrane stabilityunder heat stress | 第45-46页 |
| 2.3.4 Effects of MT and EBL priming on the activities of antioxidantenzymes under heat stress | 第46-48页 |
| 2.3.5 General transcriptomic responses of tall fescue to heat stress | 第48-49页 |
| 2.3.6 GO term and pathway enrichment analyses | 第49-52页 |
| 2.3.7 Cluster analysis and functions of heat stress responsivegenes | 第52-57页 |
| 2.3.8 Changes of hormone pathway related genes | 第57-58页 |
| 2.3.9 Effects of MT and EBL on the expression of heat stress inducedgenes | 第58-60页 |
| 2.4 Discussion | 第60-64页 |
| 3 Chapter TwoMelatonin ameliorates drought stress-induced damages of tall fescue | 第64-80页 |
| 3.1 Introduction | 第64-66页 |
| 3.1.1 Objectives | 第65-66页 |
| 3.2 Materials and Methods | 第66-70页 |
| 3.2.1 Plant materials and growth conditions | 第66页 |
| 3.2.2 Experimental design and drought stress treatment | 第66页 |
| 3.2.3 Measurement of shoot fresh weight and shoot height of tallfescue Seedlings | 第66-67页 |
| 3.2.4 Measurement of water loss and leaf water content | 第67页 |
| 3.2.5 Quantification of reactive oxygen species and antioxidantenzymes | 第67页 |
| 3.2.6 Measurement of malondialdehide and electrolyte leakage | 第67-68页 |
| 3.2.7 Measurement of chlorophyll | 第68页 |
| 3.2.8 Statistical analysis | 第68-70页 |
| 3.3 Result | 第70-78页 |
| 3.3.1 Effects of exogenous melatonin an growth conditions of tallfescue seedling | 第70-71页 |
| 3.3.2 Effects of exogenous melatonin on electrolyte leakage and totalchlorophyll content | 第71-72页 |
| 3.3.3 Effects of exogenous melatonin on shoot water loss and shootwater content | 第72-73页 |
| 3.3.4 Effects of exogenous melatonin on ROS and cell membranestability | 第73-75页 |
| 3.3.5 Effects of exogenous melatonin on the antioxidant enzymeactivities | 第75-78页 |
| 3.4 Discussion | 第78-80页 |
| 4. Conclusion | 第80-82页 |
| 5. References | 第82-108页 |
| Appendices | 第108-134页 |
| Student profile | 第134-136页 |
| Acknowledgement | 第136-137页 |
