Functional characterization of a novel potato subtilisin- like protein with caspase- 3 like activity

FERNANDEZ, MB; DALEO, GR; GUEVARA, MG

Minneapolis, Minnesota

Congreso; Annual Meeting of American Phytopathological Society; 2014

American Phytopathological Society

Caspases are key proteases involved in animal programmed cell death. In the reported plants genomes orthologous genes to caspases were not found. However, plant proteases with caspase activity have been reported in several species, being subtilisin- like proteases in three of them. None of these proteases exhibit caspase- 3 activity. Recently, we have isolated a subtilisin- like protein with caspase- 3 activity (StSBT1) from potato leaves, that is induced during P. infestans infection. The aim of this work was to analyze the role of StSBT1 and the mechanism of plant defense response. Results obtained show that StSBT was able to increase 3 fold tomato cell death and to induce cell death of potato leaves. During potato- P. infestans interaction salicylic acid (SA) signaling pathway is activated. StSBT1 was able to induce the genes WRKY1 and PR1 (SA markers). Additionally, StSBT1 induces the mRNA of the HR marker gene Hsr203J. Contrary, no differences in mRNA of NPR1 (SA maker) and StPI II (JA/ethylene marker) were detected between potato leaves treated and not with StSBT1, suggesting that StSBT1 may exert this caspase- 3 activity downstream or in a NPR1 independent pathway. Finally, this is the first report that shows the functional characterization of an extracellular subtilisin- like protein with caspase- 3 like activity in plants.