Role of glycosylation on potato aspartic proteinases secretion

M.R. PAGANO; J.R. MENDIETA, F.F. MUÑÓZ; G.R. DALEO; M. G. GUEVARA.

Montreal, Quebec, Canada

Congreso; Joint Meeting of the American Phytopathological Society and Canadian Phytopathological Society; 2006

Specific roles of glycosylation appear to be protein dependent. Plant aspartic proteases (AP) contain two or more consensus N-glycosylation sites; however, the importance of those is not well understood. We have previously reported that the effect of the glycosylation of StAP (Solanum tuberosum aspartic proteases) is important for their antimicrobial activity, because it increases the capacity to induce membrane permeabilization. In this work, we investigated the effects of two inhibitors on the secretion of StAP to the apoplast. Potato tubers were treated during 12, 24 and 48 hours with or without tunicamycin and brefeldin A (BFA), two inhibitors of glycosylation that act at different level of secretion pathway. The results showed that the treatments with tunicamycin or BFA modified the extracellular protein pattern present in tubers. Wounding induces aspartic proteases; however, when tubers were treated with the glycosylation inhibitors before wounding, the induction of these proteases was not observed. In addition, we observed that a protease inhibitor present in the apoplast was not secreted when potato tubers were treated during 24 or 48 hr with tunicamycin or BFA. The results obtained suggest that glycosylation would be involved in the secretion of these proteins in response to pathogen infection.