Polyamines in Plant Pathogenic Signaling

Abstract

The levels of polyamines in leaves of Gynura aurantiaca DC, tomato, Lycopersicon esculentum Mill cv. Rutgers, infected with citrus exocortis viroid (CEVd) or treated with ethephon (2-chloroethylphosphonic acid) were measured in relation to development of symptoms. A marked decrease in the putrescine content was observed in the plants infected with CEVd or treated with silver ions or ethephon at high concentration. These agents are potent inducers of pathogenesis-related (PR) proteins in both plants. Results obtained with inhibitors of synthesis and action of ethylene and with exogenous application of putrescine indicate that the lowering of putrescine content is a step subsequent to ethylene increase in the transduction chain somewhere between the primary pathogenic signal and the plant response. However the enhanced ethylene production in an ethylene overproducing Epinastic (Epi) tomato mutant didn’t produce either a decrease of putrescine or the accumulation of PR proteins. But when Epi plants were treated with ethephon, then both the decrease of putrescine and the accumulation of PR proteins were induced. The possible biological meaning of these findings is discussed.KeywordsEthylene BiosynthesisEthephon TreatmentPutrescine ContentViroid InfectionEnhanced Ethylene ProductionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.