Effects of Acyrtosiphon pisum (Harris) infestation on the hydrogen peroxide content and activity of antioxidant enzymes in Fabaceae plants

The H2O2 content increased in Fabaceae (pea, vetch and broad bean) plants after aphid herbivory and reached the highest level at 6 h post-infestation. Prolonged aphid feeding decreased the H2O2 content, but it was still higher in infested plants than in control ones. The maximum increase of H2O2 concentration was noted in A. pisum pea plants. A. pisum feeding reduced the CAT activity in infested plants. CAT was inhibited until 48 h after infestation in pea and vetch and until 24 h in broad bean. The pea plants drastically inhibited the CAT. Initial feeding of A. pisum (1 h, 2 h) slightly increased the APX activity in seedlings of pea and broad bean. Thus the changes in enzyme activity were dependent on plant species. The strongest inhibition and induction of APX was noted in tissues of broad bean. Our results indicated that H2O2 and H2O2-scavenging enzymes may play a significant role in the defence mechanisms of Fabaceae plants towards the pea aphid.