title: DEVDase activity is induced in potato leaves during Phytophthora infestans infection.
abstract: Programmed cell death (PCD) occurs in plants, animals and several branches of unicellular eukaryotes as a part of developmental and/or defense processes. Caspase proteases are universal mediators of animal apoptosis, a type of PCD. In plants, there are not animal caspase homologs; therefore, the characterization of caspase-like activities is of considerable importance to our understanding of PCD in plants. Here we report for the first time the involvement of caspase-3-like activity in the resistance mechanism of potato to Phytophthora infestans infection. We showed that disease development in infected potato leaves is dependent of caspase-3-like activity. Unlike plant DEVDases previously reported, this DEVDase activity was sensitive to the serine protease inhibitor PMSF. As reported for other subtilisin- like proteases with caspase activity, potato DEVDase activity was mainly localized in the apoplast. We demonstrated that in total protein extract DEVDase activity accounts for a 60% of serine proteases; however, this percentage increases to 100% in the apoplast. Additionally, this caspase-3-like activity is constitutively expressed in the apoplast of potato leaves. Total DEVDase activity is induced only in potato cultivars with high field resistance to P. infestans. These results show that potato caspase-3-like protease could constitute a tool in the potato defense mechanisms resulting in partial resistance, although further assays would be necessary in order to elucidate its role.
authors.affiliation: Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina. mbfernan@mdp.edu.ar
authors.forename: María Belén
authors.initials: MB
authors.lastname: Fernández
authors.forename: Gustavo Raúl
authors.initials: GR
authors.lastname: Daleo
authors.forename: María Gabriela
authors.initials: MG
authors.lastname: Guevara
mesh_terms: D001947:Breeding; D053148:Caspase 3 / Q000378:metabolism*; D016923:Cell Death; D060467:Disease Resistance / Q000235:genetics; D010447:Peptide Hydrolases / Q000378:metabolism*; D055750:Phytophthora infestans; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D057057:Serine Proteases / Q000378:metabolism; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D013045:Species Specificity; D020860:Subtilisin
chemical_list: D010940:Plant Proteins; D011480:Protease Inhibitors; D010447:Peptide Hydrolases; D057057:Serine Proteases; D020860:Subtilisin; D053148:Caspase 3; C108711:DEVDase