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

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

Mar del Plata, Buenos Aires, Argentina

Congreso; 43º Annual Meeting SAIB; 2007

SAIB

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 culture that was concentrated by ultrafiltration and then fractioned by acetone precipitation and anionic-exchange (AEX) and hydrophobic-interaction chromatographies (HI-FPLC). The elicitor activity of the fractions was monitored by phytopathological test with the virulent pathogen M11 and ROS production with NBT and DAB. Proteins were visualized by 2D-PAGE and subjected to MALDI/TOF-TOF. 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. This unbound protein fraction was further purified by HI-FPLC and the ROS-inducing activity was distributed in 4 peaks that bound weakly to the Phenyl-Superose matrix. Non of the active proteins presented high score in the searches of bases data, only a catalase and a SOD 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.