Expression profile of seven polyamine oxidase genes in rice () in response to abiotic stresses, phytohormones and polyamines.

Unlabelled: Polyamine levels are controlled by biosynthesis, intra- and inter-cellular flux by the respective transporters, and catabolism. The catabolism is catalyzed by two groups of enzymes. One is copper-containing amine oxidases and the other is polyamine oxidases (PAOs).

Effect of thermospermine on expression profiling of different gene using massive analysis of cDNA ends (MACE) and vascular maintenance in Arabidopsis.

polyamine oxidase 5 gene () functions as a thermospermine (T-Spm) oxidase. Aerial growth of its knock-out mutant () was significantly repressed by low dose(s) of T-Spm but not by other polyamines. To figure out the underlying mechanism, massive analysis of 3'-cDNA ends was performed.

A Polyamine Oxidase from (SelPAO5) can Replace AtPAO5 in through Converting Thermospermine to Norspermidine instead to Spermidine.

Of the five polyamine oxidases in , AtPAO5 has a substrate preference for the tetraamine thermospermine (T-Spm) which is converted to triamine spermidine (Spd) in a back-conversion reaction in vitro. A homologue of AtPAO5 from the lycophyte (SelPAO5) back-converts T-Spm to the uncommon polyamine norspermidine (NorSpd) instead of Spd. An loss-of-function mutant shows a strong reduced growth phenotype when growing on a T-Spm containing medium.

Scots pine aminopropyltransferases shed new light on evolution of the polyamine biosynthesis pathway in seed plants.

Background And Aims: Polyamines are small metabolites present in all living cells and play fundamental roles in numerous physiological events in plants. The aminopropyltransferases (APTs), spermidine synthase (SPDS), spermine synthase (SPMS) and thermospermine synthase (ACL5), are essential enzymes in the polyamine biosynthesis pathway. In angiosperms, SPMS has evolved from SPDS via gene duplication, whereas in gymnosperms APTs are mostly unexplored and no SPMS gene has been reported.

Abiotic Stress Phenotyping of Polyamine Mutants.

Plant mutants in polyamine pathway genes are ideal for investigating their roles in stress responses. Here we describe easy-to-perform methods for phenotyping Arabidopsis mutants under abiotic stress. These include measurements of root growth, chlorophyll content, water loss, electrolyte leakage, and content of the reactive oxygen species hydrogen peroxide (HO) and superoxide anion (O-).