Polyamine catabolism in plants

Abstract

The copper-dependent amine oxidases (CuAOs) and flavin-containing polyamine oxidases (PAOs) are involved in polyamine (PA) catabolic processes. Studies on plant CuAOs are still incomplete, whereas research on plant PAOs has advanced significantly in the past decade. The maize PAO, the best studied plant PAO, and the barley PAOs were shown to catalyze PAs in a terminal catabolic pathway. Therefore, plant PAOs were assumed to have terminal catabolic activity, which differs from the back-conversion activity of mammalian PAOs. However, plant PAOs that have back-conversion activity are now reported. Here, studies on PAOs from the two model species Arabidopsis thaliana and Oryza sativa are compiled, and research on CuAOs is updated. Our current understanding of the roles of PAOs and CuAOs in plant development and defense responses is described.