Constitutive and inducible proteins in the root of Chinese cabbage infected with Plasmodiophora brassicae

A plant-pathogen system consisting of a Chinese cabbage cultivar and two isolates of Plasmodiophora brassicae was developed for analysing root proteins accumulated in susceptible and resistant responses to the fungus. Proteins extracted at pH 2.8 were analysed by two-dimensional gel electrophoresis. More than 150 protein spots were resolved. Spots indicating changes in the intensity by the infection of P. brassicae were classified into six types: class 1 contains proteins enhanced in susceptible response; class 2, proteins unique to susceptible response; class 3; proteins repressed in susceptible response; class 4: proteins enhanced in resistant response; class 5, proteins unique to resistant response; and class 6, proteins repressed in resistant response. Two proteins from class 1 and one protein from class 4 were subjected to an N-terminal amino acid sequencing. One of the class 1 protein (25 kDa, pI 7.0) revealed high homology with pathogenesis-related protein group 5.