Abstract: In order to elucidate the influence of cadmium on the related physiological indexes in tobacco， 4\|week\|old tobacco Nicotiana benthamiana were treated with the cadmium concentration of 0， 50， 250 and 500 μg·L-1respectively. The changes in the contents of chlorophyll and malondialdehyde （MDA）， the activities of superoxide dismutase （SOD）， peroxidase （POD） and catalase （CAT） were determined after treatment for one week. The results showed that the content of chlorophyll， the activities of SOD and CAT were decreased， the activity of POD were firstly increased and then decreased， and the content of MDA was increased. These data suggested that exposure to lower concentration of cadmium led to self\|protection in tobacco cells， but plant cells failed to response to Cd stress with the concentration elevated to 250 μg·L-1， which was harmful to tobacco cells.

Key words: Nicotiana benthamiana, cadmium stress, physiological indexesa