The role of polyamines in response to abiotic stresses

Under the influence of various abiotic stresses, the growth, development and geographic distribution of plants change. In order to survive adverse environmental conditions and to sustain life, plants have evolved various combat and adaptive strategies to enviromntal stresses, which in the context of these defense mechanisms, is referred to metabolites accumulation such as common aliphatic polyamines (PAs) including putrescine, spermidine, and spermine.ResultsOver the last two decades, genetic, transcriptomic, proteomic, metabolomic, and phenomic modern approaches have unraveled many significant functions of different PAs in the regulation of plant abiotic stress tolerance. Studies have demonstrated that because of their polycationic nature at physiological pH, and strong binding ability to negatively charged molecules in cellular components such as nucleic acids, proteins, and phospholipids, PAs enable to largely modulate the homeostasis of reactive oxygen species (ROS) and also due to regulating and stabilizating antioxidant defense systems or suppressing ROS production improve stress tolerance in plants. Environmental stresses-induced oxidative stresses can be managed by both PAs biosynthesis and their degradation, leading protection of cell metabolism. This is ascribed to generating other metabolited and also signal molecules which participate in defense systems and energy production in Krebs cycle. ConclusionsImportant role of polyamines in stress tolerance by several lines of evidences has shown that transcript levels of polyamines-biosynthetic genes as well as the activity of related enzymes are induced by stresses. Increasing the polyamines level or expression of their biosynthetic genes through spraying with polyamines leads to an increase in stress tolerance. The reduction of polyamines has been associated with the reduction of tolerance to stress. Considering the variety of bioactivities of polyamines and their biosynthesis and degradating pathways in crop plants, this metabolic pathway in plants, identification of molecular networks and selection of effective genes can be used as candidates in breeding programs and production of stress-tolerant commercial cultivars.