Changes in antioxidant capacity of soybean and maize seedlings as a response to Rhizoctonia solani Kühn infection

Abstract

Changes in enzymatic and non-enzymatic antioxidant systems in leaves and roots of soybean and maize seedlings were studied after inoculation with Rhizoctonia solani Kühn, AG 2-2 IIIB. After the infection with R. solani, increase in superoxide anion (O2 .- ) scavenging activity was recorded only in leaves and roots of soybean plants. Hydroxyl radical (.OH), the production of which was remarkably increased in infected soybean seedlings, were invariably produced in infected maize seedlings in comparison to control. Furthermore, superoxide-dismutase activity increased only in infected maize roots, which could point to enhanced O2 .-dismutation. Nevertheless, lipid peroxidation intensity was notably recorded only in soybean plants, which could lead to presumption that .OH was successfully neutralized in maize seedlings and that membrane lipids were prevented from peroxidation with .OH, potentially the most responsible for these processes. Peroxidase were significantly active in infected leaves compared to control in both species, especially in soybean. Naturally, ROS accumulation induced significantly enhanced phenylalanin ammonialyase (PAL) activity, which escalated phenolic compounds synthesis in maize seedlings. Ability to accumulate phenolics, under the condition of pathogen attack, correlated with the results for the DPPH-assay that determines these maize plants in active group1.