Early events of the innate immunity activation by the fungal elicitor AsES in strawberry

MARTOS, GG.; TERÁN, MM.; DÍAZ RICCI, JC.

Foz do Iguazú

Congreso; 11th International Congress of Plant Molecular Biology Iguazú Falls (Argentina - Brazil). 25-30 October.; 2015

International Plant Molecular Biology

The elicitor AsES obtained from Acremonium strictum induces a strong defense response in strawberry plants and confers resistance against the fungal pathogen Colletotricum acutatum the casual agent of anthracnose disease. It is known that elicitors display a characteristic signature of its mode of activation of the immune response. Previous studies showed that AsES causes the accumulation of reactive oxygen species that peaked 4 hour post treatment (hpt), but due to the experimental approach used it was not clear whether the accumulation of ROS observed was intracellular or extracellular, or took place as a single peak. By using a different experimental setup, a more complex early events associated to the activation of the innate immunity were observed. In this work we report that strawberry plant cells treated with AsES exhibit a triphasic production of H2O2. The first phase consists in an extracellular accumulation of H2O2 that takes place immediately after the treatment with AsES and is preceded by a rapid and transient cell membrane depolarization. During this phase also takes place a rapid intracellular accumulation of Nitric Oxide (NO). Microscopic observations of mesophyll strawberry cells and Vicia faba guard cells treated with AsES showed that NO accumulates at the chloroplast. After the first extracellular H2O2 production phase, two intracellular H2O2 accumulation events occur, the first 2 hpt, and the second 7 hpt. Cell suspension treated with AsES also exhibited the alkalization of the extracellular medium.