Polyamines: potent modulators of plant responses to stress.

Polyamines (PAs) are aliphatic polycations that are widespread in living organisms. In this review, we are focusing the correlation between endogenous PA titers and physiological perturbations and on the protective role of various analogues of PAs against abiotic stresses. PAs are involved in many physiological processes, such as cell growth and development and also respond to diverse abiotic stresses. Polyamines level shifts in different ways depending on several factors, such as plant species, tolerance or sensitivity to stress, and duration of stress. Exogenously supplied PAs protected plants from abiotic stress, whereas transgenic plants overexpressing PA biosynthetic genes exhibited stress tolerance. On the other hand, loss-of-function mutant of PA biosynthetic genes, or decrease of PA titers, resulted to decrease stress tolerance. [ABSTRACT FROM AUTHOR]