Cloning, Expression and Characterization of Protein Elicitors from the Soyabean Pathogenic Fungus Phytophthora sojae

The oomycete Phytophthora sojae is a severe pathogen of soybean[ Several resistance genes against races of P[ sojae exist in soybean but the nature of corresponding avi! rulence genes is unknown[ Clones encoding four di}erent isoforms of a protein elicitor from P[ sojae "sojein 0 3# belonging to the class of acidic a!elicitins have been isolated[ These 87 amino acid proteins show high hom! ology to elicitins from other Phytophthora species[ The di}erent sojein isoforms were expressed in Escherichia coli as His!tagged fusion proteins[ Puri_ed sojein as well as recombinant sojein isoforms induce hypersensitive reaction "HR#!like lesions in tobacco but are not active as race!speci_c elicitors in soybean[ However all sojein isoforms induce defence!related genes like those encoding phenylalanine ammonia lyase\ glutathione!S!transferase and chalcone synthase in tobacco and soybean plants and cell cultures[ It is concluded that sojeins contribute to the induction of defence responses but that they are not involved in race speci_c recognition of the P[ sojae races by soybean plants