Cloning Expression and Characterization of Protein Elicitors from the Soyabean Pathogenic Fungus Phytophthora sojae
Becker. J Nagel. S Tenhaken. R
Journal of Phytopathology ; 2000 [Vol.148] Pages:161-167
Abstract
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 avirulence genes is unknown. Clones encoding four different isoforms of a protein elicitor from P. sojae (sojein 1-4) belonging to the class of acidic x-elicitins have been isolated. These 87 amino acid proteins show high homology to elicitins from other Phytophthora species. The different sojein isoforms were expressed in Escherichiacoli as His-tagged fusion proteins. Purified sojein as well as recombinant sojein isoforms induce hypersensitive reaction (HR)-like lesions in tobacco but are not active as race-specific 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 specific recognition of the P. sojae races by soybean plants.
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