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 (H 2 O 2 ), a part of an oxidative burst. The reaction was followed by an antioxidative response, with the involvement of phospholipid hydroperoxide glutathione peroxidase (PHGPX)-like protein (EC 1.11.1.9). Induction of expression of two putative PHGPX genes was observed in rubbed internodes. To characterize the importance of this antioxidant gene, enzymatic activities of glutathione peroxidase (GPX) and PHGPX were measured, respectively, with H 2 O 2 and hydroperoxide lipid as oxidant. Only PHGPX activities were induced by the mechanical treatment, suggesting a major role of PHGPX in the mechanisms of antioxidant defence in plant.