Enhancement of health-promoting and plant-protecting secondary metabolites by postharvest conditioning with hormetic doses of abiotic stresses

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Our long-term goal is to develop post-harvest conditioning technologies to enhance health-promoting (nutraceutical) and plant-protecting (phytoalexin) secondary metabolites in fresh fruits and vegetables using hormetic doses of abiotic stresses that are suitable for application in the postharvest phase. Given that plants produce secondary metabolites as weapons to combat stresses, it is possible that the response can well be tuned to achieve a balance between enhancement of dietary phytochemicals that offer plant protection and health benefits and acceptability of the produce by exposing them to controlled doses of stressors. This would require a better understanding of the link between stressors and secondary metabolites, and an understanding of the stress-induced alterations in the secondary metabolites and metabolic pathways. Thus our efforts in the short- to medium-term will be focused on gaining an understanding of the connections between hormetic doses of abiotic stressors, signal components and secondary metabolite production. The research involves: (1) the determination of hormetic doses of abiotic stresses in selected crops; (2) the selection of hormetic stresses which are effective in inducing or enhancing desired secondary metabolites without affecting sensory quality of the produce; (3) the characterization of the selected abiotic stresses and their combinations for their generation of redox and hormonal signals in the selected crops; (4) the profiling of secondary metabolites of the pathways that produce the desired phytochemicals in the crops exposed to the selected stresses and their combinations; and (5) the establishment of correlative relationships between signal components and secondary metabolites which will help identify key signal component(s) that impact the production of desired phytochemicals. Studies will be performed with carrot root and tomato fruit. Phytochemical-enriched fresh fruits and vegetables have recently been identified as a new class of functional foods. Preservation of fresh crops with enhanced attributes of health-promotion and disease resistance will not only help the fresh produce industry to reduce postharvest losses, but also help them to ensure a healthier population.