Early events in the defense reponse of strawberry to Colletotrichum spp.

TONELLO, URSULA; SALAZAR, SERGIO MIGUEL; CASTAGNARO, ATILIO PEDRO; DIAZ RICCI, JUAN CARLOS

Iguazú, Argentina

Congreso; 40º Annual Meeting SAIB; 2004

SAIB

Plants exhibit a wide array of defense strategies against potential pathogens. They possess preformed biochemical defenses and physical barriers that are presented to intruders to hinder the invasion. Additionally, fast inducible defenses may be activated by a pathogen attack. The oxidative burst, a rapid and transient generation of reactive oxygen species (ROS), is one of the earliest events of the plant defense response. We have investigated the occurrence and localization of oxidative burst in compatible and incompatible interactions of Colletotrichum spp with Fragaria x ananassa cv. Pájaro. In the incompatible interaction, leaves spray-inoculated with a conidial suspension, showed positive DAB (3,3’-diaminobenzinide) staining in small clusters of cells 2 hs after infection. These microbursts were not observed in the compatible interaction. When inoculation were carried out at the primary leaf, microbursts appeared in secondary leaves 4 hs after the infection, indicating the generation of a diffusible signal able to induce systemic microbursts. We have also studied the temporal expression of genes involved in the regulation  of the cellular redox status and others, such as the glutathione-S-transferase, Ca++ signaling and PR proteins, and evaluate their participation in the oxidative burst and the defense response observed.