Plant polyamine catabolism: The state of the art

Abstract

Polyamines have long been implicated in plant growth and development, as well as adaptation to abiotic and biotic stress. As a general rule of thumb the higher the polyamine titers the better. However, their molecular roles in plant stress responses still remain obscure. It has been postulated that they could act through their catabolism, which generates molecules which may act as secondary messengers signalling networks of numerous developmental and stress adaptation processes. Recently it was shown that plant and mammalian polyamine catabolism share critical features, giving new insight in plant polyamine catabolism. In this review, the advances in genes and proteins of polyamine catabolism in plants is presented and compared to other models.

Keywords: ROS signaling; abiotic stress; polyamine catabolism; polyamine oxidase; polyamines.

Figure 1

Model for PA catabolism in plant and mammalian cells. In plants, peroxisomes and apoplast are the sites of PA oxidation by either back-convertion or terminal oxidation, respectively. Apoplastic PA oxidation has been correlated with the regulation of gene expression [either induction of defense genes (green) or genes related to PCD (red)] via redox signals during stress, while the role for peroxisomal PA oxidation remains obscure. Moreover, it seems that the plant peroxisomal PAO oxidation is SSAT-independent. The pathway that correlates the apoplastic redox state to the regulation of the gene expression is unknown. PAO2 and PAO4 were recently found to be localized to peroxisomes (Kamada-Nobusada et al., 2008) In mammals, PAOs are localized to peroxisomes, while SMOs are localized to the cytoplasm and to the nucleus. In addition, in mammals SMOs are found in the cytoplasm and in the nucleus.