Abstract: In order to explore the ability of transcription factor NtMYB4a to participate in the regulation of tobacco (Nicotiana tabacum) resistance to drought stress, this study used NtMYB4a over-expressed strains (OE), knockout strains (KO) and wild type (WT) as materials, and simulated natural drought stress through pot experiment. Photosynthetic characteristics, root activity, the contents of chlorophyll, proline and malondialdehyde and antioxidant enzyme activities in three strains under drought stress at 0, 2, 4, 6, 8 days and 2 days after re-watering were compared and analyzed. The results showed that net photosynthetic rate (Pn), root activity, chlorophyll content, Pro content, and activities of SOD, POD and CAT in OE strains were significantly higher than those of WT strains, while transpiration rate (Tr), stomatal conductance (Gs) and MDA content were significantly lower than those of WT strains. The Pn, root activity, chlorophyll content, Pro content, activities of SOD, POD and CAT of KO strains were significantly lower than those of WT strains, while Tr, Gs and MDA content of KO strains were significantly higher than those of WT strains. Therefore, the over expression of NtMYB4a should improve the drought resistance of tobacco seedlings by increasing photosynthetic capacity, root activity and antioxidant enzyme capacity, and reducing cell membrane damage.

Key words: transcription factor , ?Nicotiana tabacum , ?drought stress , ?drought resistance , ?physiological and biochemical

摘要： 为探究转录因子NtMYB4a参与调控烟草(Nicotiana tabacum)抵抗干旱胁迫的能力，以NtMYB4a过表达株系(OE)、敲除株系(KO)和野生型(WT)为材料，通过盆栽实验模拟自然干旱胁迫，对比分析三个株系在干旱胁迫0、2、4、6、8 d和复水2 d后的光合特征、根系活力、叶绿素、脯氨酸(Pro)和丙二醛(MDA)含量以及抗氧化酶活性等指标。结果表明，OE株系的净光合速率(Pn)、根系活力、叶绿素含量、Pro含量以及SOD、POD和CAT活性均显著高于WT株系，而蒸腾速率(Tr)、气孔导度(Gs)、MDA含量则显著低于WT株系；KO株系多数时期Pn、根系活力、叶绿素含量、Pro含量及SOD、POD和CAT活性显著低于WT株系，Tr、Gs、MDA含量则显著高于WT株系。因此，超表达NtMYB4a可能通过提高烟草的光合能力、根系活力和抗氧化酶活性，减少细胞膜损伤来提高烟苗抗旱性。

关键词: 转录因子 , 烟草 , 干旱胁迫 , 抗旱性 , 生理生化