[Purification and identification of a glycoprotein elicitor (CSBI) from Magnaporthe grisea]

A glycoprotein elicitor, CSBI, isolated from hyphal cell walls of the strain 97-151a of M. grisea race ZC(13) was purified by centrifugation, ultra-filtration, gel filtration and anion exchange chromatography (Fig.1). CSBI appeared as a single band on silver-stained SDS-PAGE (Fig.2). Anthrone-colorimetric assay and Coomassie blue G-250 staining showed that the carbohydrate-to-protein ratio was 9.32 (Table 1). The induction of peroxidase activity in incompatible interactions was stronger than in compatible interactions (P<0.05) after treatment with CSBI on rice leaves (Fig.3). The N-terminal sequence of CSBI was determined to be ITPEAMLSANCCSD, which showed high homology to a 78.671-kD hypothetical protein MG07877.4 (accession No. gi38107424) from M. grisea in NCBI databases. CSBI was either identified as hypothetical protein MG07877.4 by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) with 9 matching peptides (Fig.4, Table 2).