Fortes, A.M., Faculdade de Ciências de Lisboa, Department of Plant Biology, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, Lisbon, Portugal; Agudelo-Romero, P., School of Molecular Science, The University of Western Australia, Perth, WA, Australia, ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia; Pimentel, D., Faculdade de Ciências de Lisboa, Department of Plant Biology, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, Lisbon, Portugal;

Polyamines are growth regulators that have been widely implicated in abiotic and biotic stresses. They are also associated with fruit set, ripening, and regulation of fruit quality-related traits. Modulation of their content confers fruit resilience, with polyamine application generally inhibiting postharvest decay. Changes in the content of free and conjugated polyamines in response to stress are highly dependent on the type of abiotic stress applied or the lifestyle of the pathogen. Recent studies suggest that exogenous application of polyamines or modulation of polyamine content by gene editing can confer tolerance to multiple abiotic and biotic stresses simultaneously. In this review, we explore data on polyamine synthesis and catabolism in fruit related to pre- and postharvest stresses. Studies of mutant plants, priming of stress responses, and treatments with polyamines and polyamine inhibitors indicate that these growth regulators can be manipulated to increase fruit productivity with reduced use of pesticides and therefore, under more sustainable conditions. © 2019 Fortes, Agudelo-Romero, Pimentel and Alkan.