Premium
Induction of a proteinase K inhibitor in a potato cultivar with a high degree of field resistance against Phytophthora infestans
Author(s) -
Feldman Mariana L.,
Oliva Claudia R.,
Casalongué Claudia A.,
Daleo Gustavo R.
Publication year - 2000
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2000.100103.x
Subject(s) - phytophthora infestans , cultivar , solanaceae , biology , solanum tuberosum , size exclusion chromatography , solanum , molecular mass , proteinase inhibitor , botany , horticulture , enzyme , biochemistry , blight , gene
A proteinase K inhibitor (PLPKI) was isolated from a potato cultivar with a high level of field resistance ( Solanum tuberosum L. cv. Pampeana INTA), after 24 h of infection with Phytophthora infestans , when inhibitory activity was markedly increased. Purification was performed by heat treatment, gel filtration chromatography and affinity chromatography. A size of 60 kDa was estimated by SDS‐PAGE in partially denaturing conditions and by gel filtration. It is multimeric and the monomer has a molecular mass of 8.5–9.0 kDa. PLPKI is highly active against proteinase K (EC 3.4.21.14) but poorly inhibits two serine proteinases of animal origin, trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1). A differential expression (determined by activity and immunoblotting assays) of PLPKI was observed between two potato cultivars with different degrees of field resistance to P. infestans . In the resistant cultivar (cv. Pampeana INTA) PLPKI induction (19‐fold with respect to healthy leaves) occurred 24 h after infection and remained over basal levels after 48 h infection. By contrast, in the susceptible cultivar (cv. Bintje), no induction was observed.