Inducing defence enzymes in two rice (Oryza sativa) varieties by G. mosseae arbuscular mycorrhizal fungus

Protecting plants against fundamentally radical pathogens is one of arbuscular mycorrhizal fungi's benefits. This work was aimed at comparing the effect of one such fungus (Glomus mosseae) on inducing a defensive response in two rice (Oryza sativa) varieties (LP-7 and J-104). Peroxidise, polyphenoloxidase, chitinase, (3-1,3 glucanase and phenylalanine ammonium lyase enzymatic activity and peroxidase and polyphenoloxidase isoenzymatic expression were determined in both radical and foliar tissues. Mycorrhizal colonisation and visual density percentage were also evaluated. The results revealed that the G. mosseae fungus caused variations in enzymatic activity. Differences were observed in the two varieties behaviour patterns according to evaluation time and plant área studied. The differences detected in peroxidase and polyphenoloxidase electrophoretic patterns were due to the varieties and not to mycorrhisation effect. Rice variety LP-7 generally presented a successful response to inoculation with the G. mosseae arbuscular mycorrhizal fungus, manifesting higher defence mechanism induction. The best results for protecting crops could thus be obtained by using this combination. Key words: peroxidase, polyphenoloxidase, chitinase, (3-1,3 glucanase and phenylalanine ammonium lyase