| Acknowledgements | 第9-11页 |
| Contents | 第11-14页 |
| List of Tables | 第14-15页 |
| List of Figures | 第15-16页 |
| List of Abbreviations | 第16-17页 |
| Abstract | 第17-18页 |
| 摘要 | 第19-21页 |
| Chapter 1 General introduction and review of literature | 第21-37页 |
| 1.1. Alloployploids | 第21-25页 |
| 1.2 Genetic Changes in allopolyploids | 第25页 |
| 1.3 Epigenetic Changes in allopolyploids | 第25-28页 |
| 1.3.1 DNA methylation | 第26-27页 |
| 1.3.2 Plant DNA methylation mechanisms | 第27页 |
| 1.3.3 Biological function of DNA methylation | 第27-28页 |
| 1.3.4 Plant RNA-mediated DNA methylation | 第28页 |
| 1.4 Small RNA in allopolyploids | 第28-35页 |
| 1.4.1 The discovery of miRNAs | 第28-32页 |
| 1.4.1.1 Biogensis of miRNAs | 第29-30页 |
| 1.4.1.2 Role of miRNAs in plants | 第30-32页 |
| 1.4.2 siRNAs | 第32-35页 |
| 1.4.2.1 Biogenesis of siRNAs | 第32-34页 |
| 1.4.2.2 Role of siRNAs in allopolyploids | 第34-35页 |
| 1.5 DNA methylation and small RNA relations with allopolyploids | 第35页 |
| 1.6 The objective of the study and the significance | 第35-37页 |
| Chapter 2 Phenotypic and genetic variation occurred during wide hybridisation andpolyploidisation between Brassica rapa and Brassica nigra | 第37-50页 |
| 2.1 Introduction | 第37-39页 |
| 2.2 Materials and methods | 第39-42页 |
| 2.2.1 Wide hybridisation | 第39-41页 |
| 2.2.2 Morphological observation | 第41页 |
| 2.2.3 Genomic DNA extraction | 第41页 |
| 2.2.4 Sequence related amplified polymorphism (SRAP) analysis | 第41-42页 |
| 2.2.5 Novel band isolation | 第42页 |
| 2.3 Results | 第42-48页 |
| 2.3.1 Comparison of phenotypic differences among polyploids and parents | 第42-44页 |
| 2.3.2 Confirmation of the hybrids | 第44页 |
| 2.3.3 Genetic variation analysis | 第44-45页 |
| 2.3.4 Novel band analysis | 第45-48页 |
| 2.4 Discussion | 第48-50页 |
| 2.4.1 Phenotypic and genetic variation during wide hybridisation and genome doublining | 第48-49页 |
| 2.4.2 Novel band had function gene | 第49-50页 |
| Chapter 3 DNA methylation changes during wide hybridisation and allopolyploidisation betweenBrassica rapa and Brassica nigra | 第50-62页 |
| 3.1 Introduction | 第50-51页 |
| 3.2 Materials and methods | 第51-56页 |
| 3.2.1 Plant materials | 第51-53页 |
| 3.2.2 Genomic DNA extraction | 第53页 |
| 3.2.3 MSAP response procedures | 第53-54页 |
| 3.2.4 Polyacrylamide gel electrophoresis | 第54-56页 |
| 3.2.5 Simple silver staining | 第56页 |
| 3.2.6 Data processing and analysis | 第56页 |
| 3.3 Results | 第56-59页 |
| 3.4 Discussion | 第59-62页 |
| Chapter 4 Small RNAs changes during wide hybridisation and allopolyploidisation betweenBrassica rapa and Brassica nigra | 第62-97页 |
| 4.1 Introduction | 第62-64页 |
| 4.2 Materials and methods | 第64-68页 |
| 4.2.1 Plant materials | 第64页 |
| 4.2.2 High-throughput sequencing of small RNAs | 第64-66页 |
| 4.2.3 RNA quality testing | 第66页 |
| 4.2.4 The expression of miRNAs and targeted genes using quantitative RT-PCR analysis | 第66-68页 |
| 4.3 Results | 第68-94页 |
| 4.3.1 High-throughput sequencing of small RNAs | 第68-72页 |
| 4.3.2 Known miRNAs | 第72-83页 |
| 4.3.3 Novel miRNAs | 第83-90页 |
| 4.3.4 qRT-PCR analysis of miRNAs and their target genes | 第90-94页 |
| 4.4 Discussion | 第94-97页 |
| 4.4.1 siRNAs maintains genomie stability in allopolyploids | 第94页 |
| 4.4.2 Changes in siRNA and miRNA during wide hybridisation and polyploidisation | 第94-95页 |
| 4.4.3 The expression of miRNAs and their target genes in allodiploid and allotetraploid | 第95-97页 |
| Chapter 5 Major findings and future perspectives | 第97-99页 |
| 5.1 Major findings | 第97-98页 |
| 5.1.1 Phenotypic and genetic variation | 第97页 |
| 5.1.2 DNA methylation changes | 第97页 |
| 5.1.3 Small RNA changes | 第97-98页 |
| 5.2 Future perspectives | 第98-99页 |
| References | 第99-119页 |
| Additional files | 第119-157页 |
| Publications | 第157页 |
