Regulatory Mechanisms of Polyamine Biosynthesis in Plants

Polyamines are small positively charged molecules with a widespread presence in all living organisms. In plants they modulate several aspects of growth and differentiation, and they also participate in the response to abiotic stress. Here we review the molecular mechanisms involved in the regulation of polyamine biosynthesis, which is exerted at different levels including gene expression, protein synthesis, and formation of multienzyme complexes. The importance of polyamines both in development and in stress resistance is also subtended by the phenotype of loss-of-function mutants and of overexpressing lines affecting the different genes that encode polyamine metabolism enzymes.