title: Oxidative stress response of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in banana plants, to hydrogen peroxide and paraquat.
abstract: Mycosphaerella fijiensis causes black leaf streak disease in banana and plantain. This fungus is usually attacked by reactive oxygen species secreted by the plant or during exposure to fungicide, however, little is known about the antioxidant response of the fungus. In this study, mycelia were observed to totally decompose 30 mmol/L of hydrogen peroxide (H2O2) within 120 min, liberating oxygen bubbles, and also to survive in concentrations as high as 100 mmol/L H2O2. The oxidative stress responses to H2O2, paraquat, and hydroquinone were characterized in terms of the activities of catalase and superoxide dismutase (SOD). Two active catalase bands were seen in native PAGE induced by H2O2. Band I had monofunctional activity and band II had bifunctional catalase-peroxidase activity. Two isozymes of SOD, distinguishable by their cyanide sensitivity, were found; CuZnSOD was the main one. The combination of H2O2 and 3-aminotriazole reduced the accumulation of biomass up to 40% compared with exposure to H2O2 alone, suggesting that catalase is important for the rapid decomposition of H2O2 and has a direct bearing on cell viability. The results also suggest that the superoxide anion formed through the redox of paraquat and hydroquinone has a greater effect than H2O2 on the cellular viability of M. fijiensis.
authors.affiliation: Departamento de Química ICET, Universidad Autónoma de Guadalajara, Patria 1201, Lomas del Valle 44100, Guadalajara, Jalisco, México.
authors.forename: Miguel J
authors.initials: MJ
authors.lastname: Beltrán-García
authors.forename: Gilberto
authors.initials: G
authors.lastname: Manzo-Sanchez
authors.forename: Salvador
authors.initials: S
authors.lastname: Guzmán-González
authors.forename: Carlos
authors.initials: C
authors.lastname: Arias-Castro
authors.forename: Martha
authors.initials: M
authors.lastname: Rodríguez-Mendiola
authors.forename: Martin
authors.initials: M
authors.lastname: Avila-Miranda
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ogura
mesh_terms: D001203:Ascomycota / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D028521:Musa / Q000382:microbiology*; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D013481:Superoxides; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D010269:Paraquat