Induction of 'Pathogenesis-related' Proteins in Tobacco Leaves by Physiological (Non-pathogenic) Disorders

The PR protein-inducing effect of naturally-occurring physiologicaldisorders of tobacco (‘sharilka’, due to water excess,and Mn toxicity) was established. This supports the view ofPR proteins as ‘stress’ macromolecules rather thanexclusively pathogenesis-related macromolecules. The effectsof the physiological disorders were compared with those of PVY^N-infection;all these treatments produced similar symptoms of necrotic spottingon leaves. It was demonstrated that non-pathogenic (‘physiological’)necrobiosis induced the same PR proteins as did infectious necrobiosis. Key words: PR proteins, tobacco, physiological disorders