Polyamine Metabolism Responses to Biotic and Abiotic Stress.

Plants have developed different strategies to cope with the environmental stresses they face during their life cycle. The responses triggered under these conditions are usually characterized by significant modifications in the metabolism of polyamines such as putrescine, spermidine, and spermine. Several works have demonstrated that a fine-tuned regulation of the enzymes involved in the biosynthesis and catabolism of polyamines leads to the increment in the concentration of these compounds. Polyamines exert different effects that could help plants to deal with stressful conditions. For instance, they interact with negatively charged macromolecules and regulate their functions, they may act as compatible osmolytes, or present antimicrobial activity against plant pathogens. In addition, they have also been proven to act as regulators of gene expression during the elicitation of stress responses. In this chapter, we reviewed the information available till date in relation to the roles played by polyamines in the responses of plants during biotic and abiotic stress.