Polyamines and environmental challenges: recent development

In this review, we will try to summarize some recent data concerning the ch anges in polyamine metabolism (biosynthesis, catabolism and regulation) in higher plants subjected to a wide array of environmental stress conditions and to describe and discuss some of the new advances concerning the differe nt proposed mechanisms of polyamine action implicated in plant response to environmental challenges. All the data support the view that putrescine and derived polyamines (spermidine, spermine, long-chained polyamides) may hav e several functions during environmental challenges. In several systems (ex cept during hypoxia, and chilling tolerance of wheat and rice) an induction of polyamines (spermidine, spermine) not putrescine accumulation, may conf er a stress tolerance. In several cases stress tolerance is associated with the production of conjugated and bound polyamines and stimulation of polya mine oxidation. In several environmental challenges (osmotic-stress, salini ty, hypoxia, environmental pollutants) recent results indicate that both ar ginine decarboxylase and ornithine decarboxylase are required for the synth esis of putrescine and polyamines (spermidine and spermine). Under osmotic and sail-stresses a production of cadaverine is observed in plants. A new s tudy demonstrates that under salt-stress putrescine catabolism (via diamine oxidase) can contribute to proline (a compatible osmolyte) accumulation. ( C) 1999 Elsevier Science Ireland Ltd. All rights reserved.