Aluminum affects the antioxidant activity of tobacco cells and the expression of salicylate-induced protein kinase (SIPK)

Abstract

It has been shown that Aluminum (Al) toxicity results in over-production of reactive oxygen species (ROS). Despite the fact that ROS can induce MAPK activation, no direct genetic evidence has linked ROS-induced MAPK activation with Al toxicity. The effect of Al on the activation of antioxidant systems in connection with the expression of salicylate-induced protein kinase (SIPK), was examined in tobacco cells. Suspension-cultured tobacco cells (Nicotiana tabacum L. cv. 'Barley 21') were treated with or without 80 μM Al. Certain parameters related to antioxidant activity were measured. A MAPKK inhibitor (PD98059) was also applied together with or without Al treatments and semi quantitative RT-PCR was applied to show the expression level of the SIPK gene. Treatment with Al rapidly increased the radical scavenging capacity of cells, catalase and superoxide dismutase activities, and expression of the SIPK gene, as compared to the control cells. In the presence of Al + PD98059, a decrease in catalase and superoxide dismutase activities was observed, compared to those cells which were treated only with Al. These results suggested that a short treatment with Al induced the activity of certain antioxidant enzymes in tobacco cells and that this response was mediated by a MAPK signal transduction pathway.