Harpin(PSS)-induced peroxidase and lignin accumulation in tobacco during the hypersensitive response

Harpin(pss), a pathogenic protein encoded by hrpZ in the hrp gene cluster o f Pseudomonas syringae pv. syringae, induces the hypersensitive response (H R) in tobacco (Nicotiana tabacum L. cv. Xanthi). An increase in peroxidase activity, lignin content and salicylic acid was observed during the HR elic ited by harpin. The increase in anionic, moderately anionic and cationic pe roxidase isozymes is positively correlated with the HR in tobacco. In addit ion, the increase of the anionic peroxidase isozyme (pI 3.5) is correlated with a rise of the transcript of the encoding gene.