The induction of the defense response mediated by the elicitor AsE1 of A. strictum does not require the integrity of the apoplast

GUSTAVO GABRIEL MARTOS; DÍAZ RICCI, JUAN CARLOS

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

There are various types of interactions between plants and eliciting molecules throughwhich a series of biochemical reactions associated with the defense response is triggered.The production of reactive oxygen species (ROS) plays a crucial role in signal transductionand therefore their measurement and kinetics is a very useful tool in the study of defenseresponse in plants. In previous studies we could verify the generation of ROS as a result ofthe interaction between strawberry plants (Fragaria x ananasa), Pájaro variety, and asubtilisin type elicitor protein produced by the fungus Acremonium scrictum. In this studywe evaluated the importance of the integrity of the apoplast in the perception of the elicitormolecule mentioned above. We worked with suspensions of 1x106 cells / mL of 8 weekstrawberry cv. Pájaro mesophyll. The cells were isolated by homogenization of leaflets anddifferential centrifugation. Then, they were resuspended in W5 buffer at pH 5.6.Theintracellular and extracellular levels of H2O2 were measured by fluorometry using theprobes H2DFFDA and Pyranine respectively. We observed a rapid intracellularaccumulation and extracellular decrease of H2O2 in the same instant that the induction withthe elicitor cells occurred, possibly caused by a diffusion effect of H2O2 from the middle tothe cytosol. Also we observed a biphasic kinetics of intracellular H2O2 with a sharp peak at2 h and another wider at 7 h post induction, which coincided with the results previouslyobserved in plants demonstrating that the integrity of the apoplast is not required in theinduction of the defense mechanism mediated by the elicitor.