Abstract: To study the effects of drought stress on physiological and biochemical characteristics and the differential expression of NtDEGP5 gene in different tobacco cultivars, drought resistant variety NC82 and drought sensitive Yunyan 87 were used as materials, and PEG-6000 was used to treat seedlings with drought stress. Fv/Fm, SOD activity, POD activity, MDA content and NtDEGP5 relative expression of two tobacco cultivars were determined after treatment, so as to provide a basis for further research on the function of NtDEGP5 gene. The results showed that drought stress had effects on Fv/Fm, SOD activity, POD activity and MDA content of tobacco seedlings. As the drought continued, Fv/Fm showed a gradual decline trend, while POD, SOD activity and MDA content showed a trend of first increasing and then decreasing. The response of different varieties to drought stress was different. Under drought stress for 0 to 9 hours, the Fv/Fm of Yunyan 87 seedlings decreased more than that of NC82, while the POD, SOD activity and MDA content increased less than that of NC82. The difference was not significant after 12 hours of drought stress. Under drought stress, the expression of NtDEGP5 was different among varieties and organs. The expression levels in roots, stems and leaves of Yunyan 87 seedlings were very low, and that in roots of NC82 seedlings was also very low, but it was high in leaves and stems after treatment for 9–12 h. NtDEGP5 expression in leaves of NC82 was positively correlated with Fv/Fm, POD activity and MDA content. The results showed that Fv/Fm, SOD activity, POD activity and MDA content could be used as drought resistance evaluation indicators of tobacco seedlings. NtDEGP5 gene expression was significantly correlated with drought resistance evaluation indicators. It was speculated that NtDEGP5 had drought resistance function.

Key words: Nicotiana tabacumt, drought stress, NtDEGP5 gene, gene expression difference analysis

摘要： 以烟草Nicotiana tabacum抗旱品种NC82和干旱敏感品种云烟87幼苗为材料，利用PEG-6000对幼苗进行干旱胁迫处理，研究干旱胁迫对烟草不同品种Fv/Fm、SOD活性、POD活性、MDA含量等生理生化指标及NtDEGP5基因表达的影响，为进一步开展NtDEGP5基因的功能研究提供依据。结果表明，干旱胁迫对烟苗的Fv/Fm、SOD活性、POD活性、MDA含量有影响，随着干旱的持续，Fv/Fm呈逐渐下降趋势，POD、SOD活性和MDA含量呈先升高后降低的趋势；不同品种对干旱胁迫的响应有差异，在干旱胁迫0～9 h，云烟87幼苗的Fv/Fm降幅大于NC82，POD、SOD活性、MDA含量的增幅小于NC82，胁迫12 h后与对照差异不显著。干旱胁迫下不同品种、不同器官间的NtDEGP5基因表达有差异，云烟87幼苗根、茎、叶中的表达量均较低，NC82幼苗根中的表达量较低，但干旱胁迫9～12 h后叶和茎的表达量较高。NC82幼苗叶片NtDEGP5基因表达量与Fv/Fm、POD活性、MDA含量呈显著正相关。Fv/Fm、SOD活性、POD活性、MDA含量可作为烟草苗期抗旱性评价指标，NtDEGP5基因表达量与抗旱评价指标显著相关，该基因可能具有抗旱性功能。

关键词: 烟草, 干旱胁迫, NtDEGP5基因, 基因表达差异分析