Induction of oxidative stress and GPX-like protein activation in tomato plants after mechanical stimulation

In Lycopersicon esculentum Mill. (cv. VFN8), mechanical stimulation induced a rapid and transient increase of hydrogen peroxide (H2O2), apart of an ox idative burst. The reaction was followed by an antioxidative response, with the involvement of phospholipid hydroperoxide glutathione peroxidase (PHGP X)-like protein (EC 1.11.1.9), Induction of expression of two putative PHGP X genes was observed in rubbed internodes. Tot characterize the importance of this antioxidant gene, enzymatic activities of glutathione peroxidase (G PX) and PHGPX were measured, respectively, with H2O2 and hydroperoxide lipi d as oxidant, Only PHGPX activities were induced by the mechanical treatmen t, suggesting a major role of PHGPX in the mechanisms of antioxidant defenc e in plant.