| Acknowledgement | 第11-15页 |
| List of Tables | 第15-16页 |
| List of Figures | 第16-17页 |
| Abbreviations | 第17-18页 |
| 摘要 | 第18-19页 |
| ABSTRACT | 第19-20页 |
| CHAPTER 1 LITERATURE REVIEW | 第21-36页 |
| 1.1 Chromium in the environment | 第22-23页 |
| 1.1.1 Chromium in water | 第22页 |
| 1.1.2 Chromium in soil | 第22-23页 |
| 1.2 Chromium in plants | 第23-26页 |
| 1.2.1 Chroium uptake | 第23-24页 |
| 1.2.2 Chromium accumulation and translocation | 第24-25页 |
| 1.2.3 Plants with phytoremediation potential of Cr contamination | 第25-26页 |
| 1.3 Effects of Cr on growth and development in plants | 第26-29页 |
| 1.3.1 Germination | 第26-27页 |
| 1.3.2 Root growth | 第27-28页 |
| 1.3.3 Stem growth | 第28页 |
| 1.3.4 Leaf growth | 第28-29页 |
| 1.3.5 Ultrastructural changes | 第29页 |
| 1.4 Effects of Cr on physiological processes in plants | 第29-34页 |
| 1.4.1 Photosynthesis | 第29-31页 |
| 1.4.2 Mineral nutrition | 第31页 |
| 1.4.3 Enzymes and other compounds | 第31-32页 |
| 1.4.4 Genotoxicity | 第32页 |
| 1.4.5 Cr-induced changes in proteomics | 第32-33页 |
| 1.4.6 Cr-induced alterations in miRNAs expression | 第33-34页 |
| 1.5 Research objectives | 第34-36页 |
| CHAPTER 2 CHROMIUM-INDUCED CHANGES IN GROWTH,ULTRASTRUCTURE,MINERALCONCENTRATION AND PHOTOSYNTHETIC PERFORMANCE IN TOBACCO | 第36-46页 |
| 2.1 Materials and methods | 第37-39页 |
| 2.1.1 Plant culture and Cr treatment | 第37页 |
| 2.1.2 Growth measurement and metal analysis | 第37-38页 |
| 2.1.3 Measurement of chlorophyll content,photosynthetic parameters and chlorophyllfluorescence | 第38页 |
| 2.1.4 Examination of ultrastructure | 第38-39页 |
| 2.1.5 Statistical analysis | 第39页 |
| 2.2 Results | 第39-43页 |
| 2.2.1 Growth traits and metal concentration | 第39-41页 |
| 2.2.2 Chlorophyll content and photosynthetic parameters | 第41-42页 |
| 2.2.3 Ultrastructure of chloroplasts | 第42-43页 |
| 2.3 Discussion | 第43-45页 |
| 2.4 Conclusion | 第45-46页 |
| CHAPTER 3 GENOME-WIDE IDENTIFICATION OF Cr STRESS-RESPONSIVE microRNAsAND THEIR TARGET GENES IN TOBACCO ROOTS | 第46-80页 |
| 3.1 Materials and methods | 第48-51页 |
| 3.1.1 Plant culture and Cr treatment | 第48页 |
| 3.1.2 Total RNA extraction,library preparation and sequencing of small RNAs | 第48-49页 |
| 3.1.3 Bioinformatic analysis of small RNA | 第49页 |
| 3.1.4 Novel miRNA prediction | 第49-50页 |
| 3.1.5 Differential expression of Cr-responsive miRNA | 第50页 |
| 3.1.6 Target prediction of miRNAs and their functional categorization | 第50页 |
| 3.1.7 qRT-PCR validation | 第50-51页 |
| 3.1.8 Statistical analysis | 第51页 |
| 3.2 Results | 第51-75页 |
| 3.2.1 High-throughput sequencing of tobacco small RNAs | 第51-54页 |
| 3.2.2 I denticcation and evolutionary conservation of conserved miRNA families | 第54-66页 |
| 3.2.3 Identification of non-conserved miRNA families | 第66-67页 |
| 3.2.4 Chromium responsive miRNAs | 第67-73页 |
| 3.2.5 qRT-PCR validation | 第73-74页 |
| 3.2.6 Target prediction | 第74-75页 |
| 3.3 Discussion | 第75-79页 |
| 3.3.1 Evolutionary conservation of miRNAs in tobacco | 第75-76页 |
| 3.3.2 Chromium responsive known miRNAs and their targets | 第76-79页 |
| 3.3.3 Chromium responsive novel miRNAs and their targets | 第79页 |
| 3.4 Conclusion | 第79-80页 |
| CHAPTER 4 DIFFERENCE OF Cr-INDUCED CHANGESINLEAFPROTEINPROFILEINTHE TWOCONTRASTING TOBACCO GENOTYPES | 第80-92页 |
| 4.1 Materials and methods | 第81-84页 |
| 4.1.1 Plant material,growth conditions and Cr treatment | 第81页 |
| 4.1.2 Protein extraction and 2-dimensional gel electrophoresis | 第81-82页 |
| 4.1.3 Protein visualization,image analysis and quantification | 第82-83页 |
| 4.1.4 Peptide and protein identification by database search | 第83页 |
| 4.1.5 qRT-PCR analysis | 第83页 |
| 4.1.6 Statistical analysis | 第83-84页 |
| 4.2 Results | 第84-89页 |
| 4.2.1 Differential Cr-induced protein expression in leaves of the two genotypes | 第84-88页 |
| 4.2.2 Guiyan 1 shows higher expression of genes corresponding to Cr up-regulated proteins | 第88-89页 |
| 4.3 Discussion | 第89-91页 |
| 4.4 Conclusic | 第91-92页 |
| CHAPTER 5 MAJOR FINDINGS AND FUTURE PROSPECTS | 第92-93页 |
| REFERENCES | 第93-102页 |
