Proteins secreted by an avirulent strain of Colletotrichum spp. induce resistance in strawberry

CHALFOUN NADIA REGINA; MUÑÓZ BLANCO JUAN; CABALLERO REPULLO JOSÉ LUIS; CASTAGNARO ATILIO PEDRO; DÍAZ RICCI JUAN CARLOS

Mar del Plata, Bs. As. Rep. Argentina

Congreso; XLIII Reunión Anual de SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular); 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

We have previously reported that the avirulent isolate M23 of C. fragariae protects the cv Pájaro of strawberry against anthracnose and that the conidial extracts derived from that strain induced HR, autofluorescence and oxidative burst. The aim of this work is to investigate the proteins secreted by the isolate M23. Proteins were obtained from free-cell liquid cultures that were concentrated by ultrafiltration and then fractioned by acetone precipitation and anionic-exchange (monoQ-FPLC) and hydrophobic-interaction chromatographies (Phenyl Superose-FPLC). The elicitor activity of the fractions was monitored by phytopathological test with the virulent pathogen M11 and ROS production. Proteins were visualized by 2D-PAGE and subjected to MALDI-TOF/TOF MS/MS. Results showed that elicitor activity was found in the flow-trough of the mono Q (pH 7.5), indicating the presence of basic active proteins. When this unbound protein fraction was further applied to the PS matrix, the ROS-inducing activity was distributed in 4 peaks that bound weakly to it. None of the active proteins presented high score in the searches with PMF in databases, only enzymes scavengers of ROS were identified in fractions that lacked elicitor activity. These results indicate that the strain M23 secrets proteins with different functions, some of which are involved in the activation of plant defense mechanisms.