The chemical induction of PR (b) proteins and resistance to TMV infection in tobacco.

Aspirin injected into Xanthi-nc tobacco leaves induces the production of PR protein and resistance to TMV. The concentration of PR protein and resistance increases with increasing aspirin concentration, up to a plateau. 2-Thiouracil and dioxohexahydrotriazine also induce PR protein when injected into tobacco leaves. Barium and manganese salts induced PR protein, but those of eight other cations did not. Certain salts were phytotoxic but did not induce PR protein, confirming that the production of PR protein is not a non-specific stress response.