Multivariate Analysis Reveals Different Responses of Antioxidant Defense in Wheat Plants Exposed to Arsenic (As) and Cadmium (Cd)

Background: Multivariate analysis is a chemometric tool that has been little explored to determine physiological status under heavy metal stress. Nevertheless, PCA has an unexplored potential to determine the plant physiologic status and its modification under stress factors like heavy metals. Objectives: This work aims to assess the physiological and biochemical effects and responses of wheat plants under the different exposition of As and Cd using multivariate models. Material and Methods: Wheat plants growing in a greenhouse were exposed to 0, 10 and 50 mg kg-1 soil of As and 0, 10 and 33 50 mg kg-1 soil of Cd until growth stage 5. After 56 days, wheat leaves and roots were collected to determine dry weight, lipid peroxidation and the activity of three enzymes: catalase, ascorbate peroxidase and guaiacol peroxidase. These measures were considered as the variables of three performed multivariate models to determine physiological status. Results: Through the interpretation of score plot and loading plot in combination, it was possible to determine that both As and Cd affect chlorophyll content and antioxidant response. However, a chlorophyll decrease and a lipid peroxidation increase were observed together with an inhibition of antioxidant response more accentuated in wheat plants exposed to As than those exposed to Cd. Conclusion: Multivariate analysis allows us to determine the differences between the physiological behavior of both stressors, which turn this chemometric tools useful for the characterization of a physiological response.