Antioxidant systems of three invasive ragweeds from the Vojvodina province: Ambrosia artemisiifolia, A. trifida and Iva xanthifolia

The combination of reproductive success with high stress tolerance (through osmotic adjustment and antioxidants) is essential for invasion success, particularly in stressful environments in the frame of global change.Antioxidant capacity could be a possible marker of adaptation to variable environmental conditions, since change in amount of antioxidants represents one of the first responses to various environmental stimuli. Among investigated ragweeds, I. xanthifolia leaves had more pronounced guaiacol-peroxidase (GPx) activity (2.5- to 9.7-fold) than A. artemisiifolia and A. trifida. A. artemisiifolia and I. xanthifolia leaves have similar reduced glutathione (GSH) content (13.05 μmol g-1 fr. w.), while A. trifida had 1.3-fold lower GSH concentration. However, superoxide-dismutase (SOD) activity was invariable in all investigated plants (234.1-247.5 U g-1 fr. w.). The highest content of total phenolics, tannins, flavonoids and proanthocyanidins were detected in A. trifida leaves (up to 3.7-fold the amount of the others). According to antioxidant activity (O2˙-, ˙OH and DPPH-scavenging tests), investigated ragweed species could be presented in a scale: A. trifida > I. xanthifolia > A. artemisiifolia. Accumulation of non-enzymatic antioxidants and lower content of GSH point to different oxidative stress avoidance strategies of A. trifida when compared to A. artemisiifolia and I. xanthifolia within the same environmental conditions