Abstract: In order to explore the effect of cadmium stress on tobacco growth and its regulation mechanism, DR5∷GUS Yunyan 87 transgenic homozygous strain was used as  material in this study. Five cadmium concentrations of 0, 5, 10, 20, 40 μmol·L^-1 were set up by nutrient solution hydroponics. The biomass, chlorophyll, antioxidant capacity, cadmium content, auxin distribution and content and auxin-related gene expression of tobacco seedlings treated with different concentrations of cadmium were studied. The results indicated that with the increase of cadmium level, the cadmium content in tobacco seedlings increased significantly, and the toxic effect of cadmium stress on tobacco seedlings increased gradually. Compared with the control, the biomass of  tobacco seedlings decreased significantly by 73.1%,  chlorophyll content decreased by 75.5%, and the auxin content of the aboveground and lower parts decreased significantly by 59.6% and 84.5%, respectively, and the relative expression levels of the related genes NtYUCCA4, NtYUCCA6, NtYUCCA8, NtYUCCA9, NtPIN1a, NtPIN1c, NtPIN4 and NtPIN9 were significantly decreased, and the MDA content was significantly increased under the cadmium stress of 40 μmol·L^-1. The decreased expression level of the synthesis of auxin NtYUCCA gene family and the auxin polar transport protein NtPINs gene family might be an important reason for the inhibition of tobacco seedling growth under cadmium stress.

Key words: cadmium, tobacco, auxin, NtYUCCA, NtPINs, gene expression

摘要： 为了探究镉胁迫对烟草生长发育的影响及其调控机制，以DR5∷GUS云烟87转基因纯合株系作为供试材料，采用营养液水培法，设置0、5、10、20、40 μmol·L^-1共5种镉浓度，研究不同浓度镉处理下烟草幼苗生物量、叶绿素含量、抗氧化能力、镉含量、生长素分布及水平变化，并检测生长素合成（NtYUCCA4、NtYUCCA6、NtYUCCA8、NtYUCCA9）和生长素极性运输（NtPIN1a、NtPIN1c、NtPIN4、NtPIN9）相关基因的表达差异。结果显示，随着供镉水平的提高，烟苗中镉含量显著增加，镉胁迫对烟草幼苗的毒害作用逐渐加大。与对照相比，在40 μmol·L^-1的镉胁迫下，烟苗的生物量显著下降73.1%，叶绿素含量显著降低75.5%，地上部和地下部生长素含量分别显著下降59.6%和84.5%，生长素相关基因NtYUCCA4、NtYUCCA6、NtYUCCA8、NtYUCCA9和NtPIN1a、NtPIN1c、NtPIN4、NtPIN9相对表达量均显著降低，丙二醛（MDA）含量显著升高。镉胁迫下，参与合成生长素的NtYUCCA基因家族与生长素极性运输蛋白基因NtPINs家族的表达水平下降，可能是烟苗生长受到抑制的重要原因。

关键词: 镉, 烟草, 生长素, NtYUCCA, NtPINs, 基因表达