Oxidative Stress and Apoptosis of Gaeumannomycesgraminis ( Get) Induced by Carabrone

Carabrone is isolated from Carpesium macrocephalum Franch. et Sav, which has good fungicidal activity, especially for Geaumannomyces graminis (Get). According to previous studies, we speculated that carabrone targets the mitochondrial enzyme complex III of Get. To elucidate the mode of action, we used carabrone to induce oxidative stress and apoptosis in Get. Incubation with carabrone reduced the burst of reactive oxygen species (ROS) and mitochondrial membrane potential, as well as phosphatidylserine (PS) release. Carabrone caused ROS accumulation in mycelia by inhibiting the activity of antioxidase enzymes, among which, inhibition of glutathione reductase (GR) activity was most obvious. The catalytic center of GR consists of L-cysteine residues that react with the α-methylene-γ-butyrolactone active site of carabrone. Additionally, a positive TUNEL reaction led to diffusion of the DNA electrophoresis band and upregulation of Ggmet1 and Ggmet2. We propose that carabrone inhibits antioxidant enzymes and pr...