Modification of membrane lipid peroxidation and antioxidant enzymes activation in transgenic rice resistant to Rhizoctonia solani

Abstract

Activation of membrane lipid peroxidation and antioxidant enzymes were investigated in transgenic rice (Oryza sativa L.) lines J6 and J61 expressing the rice chitinase gene (RCH10) and the alfalfa â-1,3-glucanase gene (AGLU1). Our results show enhanced resistance of both lines to Rhizoctonia solani, the causal agent of rice sheath blight disease. While  malondialdehyde (MDA) was significantly generated with increasing  infection time, maximum production in wild-type (WT) transgenic lines J6 and J61 (44.35, 35.00 and 38.65 ìmol/g FW, respectively) occurred after 4 days. Analysis of superoxide dismutase (SOD) activity after 2 days inoculation also revealed distinct differences between WT (34.45 U/mg protein) and the 2 transgenic lines (J6; 45.86 U/mg protein; J61, 71.90 U/mg protein). On the other hand, the activities of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were found to be quite similar in all 3 lines. Taken together, these findings suggest that MDA content and SOD activity might play important roles in enhancing pathogen resistance in the transgenic plants. Our study provides a valuable route to analyze the mechanism of transgene-mediated defense in transgenic rice.

Key words: Transgenic rice, resistance, sheath blight, Rhizoctonia solani, membrane lipid peroxidation, antioxidant enzymes.