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

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