Catalase and peroxidase activities in tobacco roots inoculated by Glomus mosseae.

BLILOU, IKRAM¹, PABLO BUENO², JOSE M. GARCIA-GARRIDO¹ & JUAN A. OCAMPO¹.

1- Dpto. Microbiología del suelo y Sistemas Simbióticos. 2- Dpto. Bioquímica, Biología Molecular y Celular de Plantas. EEZ.CSIC.Profesor Albareda,1.18008, GRANADA, SPAIN.

During the early stages of roots colonisation by arbuscular mycorrhizal fungi, a transient and weak defence response has been described. Catalases and peroxidases, enzymes involved in plant defense response, were studied throughout the colonisation of tobacco roots by the arbuscular mycorrhizal fungi Glomus mosseae.
An increase of catalase and peroxidase activities was observed at the beginning of the colonisation. The peak of activities coincided with the massive invasion of the root surface by the fungal hyphae and apresoria formation. When the fungus was established into the root, the activities of these enzymes decreased to the same levels as in nonmycorrhizal roots.
These results indicate that activation of plant defense response during the early stage of colonisation is related with the recognition between the two partner, when they recognise each other, this response is suppressed.