Antioxidant Responses of Helianthus annuus L. under Vanadium Stress.
Subject Areas : Stress Physiology
                                                    
                                                             Masoumeh Abedini
                                                        
                                                            1
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                                                    ,
                                                    
                                                             Fatemeh Mohammadian Fatemeh Mohammadian
                                                        
                                                            2
                                                        
                                                    
    ,                                                    
                                                             Behrokh Daie-Hassani
                                                        
                                                            3
                                                        
                                                    
    ,                                                    
                                                             Leila Zarandi-Miandoab
                                                        
                                                            4
                                                                
                                                                     
                                                                
                                                        
                                                    
                                    
                                               1 -     Faculty of Basic Sciences, Payame Noor University, Iran
                                               
                                               2 -     Faculty of Basic Sciences, Payame Noor University, Iran
                                               
                                               3 -     Faculty of Basic Sciences, Payame Noor University, Iran
                                               
                                               4 -     Department of Biology, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran
                                               
                                       
Keywords: MDA, Proline, Helianthus annuus, H2O2, free amino acids, Antioxidant enzymes,
Abstract :
Vanadium (V) is a transition metal consistently distributed in the Earth’s crust. At trace concentrations, it has been described as a beneficial element for some organisms; however, it is toxic at higher concentrations. This study was conducted hydroponically in a complete randomized design to investigate effects of V (0, 3.25, 7.5, and 15 mg L-1) on antioxidant system of sunflower. Results showed that all applied concentrations of V significantly decreased the plant growth, but increased the free amino acids, proline, malondialdehyde and H2O2 contents of plants. The antioxidant enzymes activities increased in response to the increase in V concentration. The activity of (Guaiacol) peroxidase showed a significant increase at 15 mg L-1 V while the activities of catalase, glutathione reductase, and ascorbate peroxidase decreased significantly by application of V. There was a slight increase in the superoxide dismutase activity at different concentrations of V. The study concludes that the applied concentrations of V induced oxidative stress in sunflower and (Guaiacol) peroxidase was a more effective antioxidant enzyme in scavenging the free radicals in this plant.
 
                                