Studies on Hypersensitive Response Mediated by TMV Resistance Gene N in Nicotiana tabacum Construction of Plant Expression Vector and Genetic Transformation Analysis of Arabidopsis thaliana AtPI Gene in Nicotiana tabacum Differences in NH3 compensation point among tobacco (Nicotiana Tabacum L.) cultivars and its relationship with N metabolization Comparison of NAC Transcription Factor Involved in Secondary Vascular Development between Populus tomentosa and Tobacco Cloning and Analysis of the Full Length cDNA of SKP1 Gene from Nicotiana tabacum var. samsun NN and Its Expression in E. coli The Effect on Photosynthetic Characteristics of Transgenic Tobacco with BnDREB1-5 Gene by Drought Stress Assessment of Genetic Relationships between the Flue-cured Tobacco Varieties by RAPD and ISSR Markers Construction of Plant Expression Vector and Genetic Transformation Analysis of Arabidopsis thaliana CYCD2;1 Gene in Nicotiana tabacum