The Tolerance to Abiotic Stresses Mediated by DREB-like Transcription Factors in Nicotiana tabacum A High-frequency in vivo-in vitro Experimental System for Embryogenesis Study Study on the construction of antisense expression vector of Glycine max oleic acid desaturase gene and its transfer to Nicotiana tabacum Effects of bio-organic fertilizer on neutral aroma component content in flue-cured tobacco in east of Gansu Province and its mechanisms The Association Analysis of Aroma Components with SSR Markers in Flue-cured Tobacco(Nicotiana tabacum)