ABSTRACT
Polyamines (PAs) are essential N-containing polycationic compounds that play a key role in growth and development and abiotic stress tolerance as hub molecules. Their biosynthesis, as well as catabolism, is fundamental to their function in plants. Moreover, there is a strong interconnection of PAs with other important regulatory molecules such as nitric oxide, hydrogen peroxide, and gamma-aminobutyric acid, which also makes PAs essential to plants. Despite enormous literature related to PA function, there is a big gap in our knowledge concerning their precise mode of action in abiotic stress tolerance. The picture is getting more complex as PA content and spectra show distinct alterations depending on the developmental stage, the organ, or the level of stress conditions of plants. Enhancement of abiotic stress tolerance of plants by PAs can be induced by the application of exogenous PAs or modification of their mechanism by transgenic methods. In this chapter, we provide an overview of the functions of different PAs and their crosstalk with other molecules during abiotic stress conditions, and point to those mechanisms that are promising targets to develop abiotic stress-resilient plants contributing to sustainable agriculture and food supply.
