Elicitation of defense reactions in strawberry (Fragaria x ananassa) by elicitor derived from Colletotrichum

CHALFOUN NADIA REGINA; ARIAS MARTA EUGENIA; SALAZAR SERGIO MIGUEL; CASTAGNARO ATILIO PEDRO; DÍAZ RICCI JUAN CARLOS

Tafí Del Valle, Tucumán. Rep. Argentina.

Jornada; XXII Jornadas Científicas de la Asociación de Biología de Tucumán; 2005

Asociación de Biología de Tucumán

The oxidative burst generating reactive oxygen species (ROS: H2O2, O2- ) is one of the earliest plant responses activated by a defense elicitor. Accumulation of H2O2 can trigger cell wall thickening, induction of defense genes and a localized cell death called hypersensitive response (HR). The aim of the study was to analyze the occurrence of defense reactions in response to a fungal elicitor in strawberry plants. The elicitor was obtained from culture filtrate of an avirulent strain of Colletotrichum fragariae and infiltrated on the abaxial surface of two leaves per plant of the cultivar Pájaro. Histochemical localization of H2O2 showed spread micro-bursts in treated leaves with a maximum accumulation four hours after infiltration. In the same areas we have also detected the reinforcement of mesophyll cell wall due to the apposition of lignin and the  swelling of few adaxial epidermal cells followed by their collapse 24 hours latter. HR cell death was visualized at infiltration sites by yellow autofluorescence under UV-light (310 nm) excitation indicating the accumulation of polyphenols. Our results indicate that the H2O2 burst is closely associated with HR and the lignification. These local defense responses induced a systemic protection when plants were challenged with a virulent pathogen.