Chromatographic purification and characterization of elicitors of necrosis on tobacco produced by incompatible Phytophthora species

A chromatographic procedure was developed to purify the proteins eliciting necrosis in tobacco and produced in culture by three species of Phytophthora: cryptogein from P. cryptogea, cinnamomin from P. cinnamomi and capsicin from P. capsici. The procedure included ion-exchange chromatography and gel filtration on Sephadex G-25. Polyacrylamide gel electrophoresis data and the amino acid composition are in agreement with a molecular mass near 10 000 for these proteins. Their behaviour on ion-exchange columns indicates that cryptogein and cinnamomin are basic proteins and capsicin an acidic one. In biological tests on excised tobacco leaf, cryptogein and cinnamomin exhibited an activity 50–100-fold that of capsicin.