Controlled Environments for Production of Value-added Food Crops with High Phytochemical Concentrations: Lycopene in Tomato as an Example

Abstract

<jats:p>Plants produce various phytochemicals that are of nutritional and medicinal value to humans. Phytochemicals having antioxidant capacity are drawing increased interest from consumers. Population studies among Americans have consistently demonstrated inadequate consumption of fruit and vegetables. Improving intake of fruit and vegetables has been a major public health effort for many years with minimal success. Given this, it seems opportunistic to consider other approaches to enhance the nutritional quality of the American diet. One plausible approach is the development of fresh produce containing a greater concentration of phytochemicals known to improve health, thus while consuming fewer servings of produce, Americans would still have significant exposure to health-promoting food constituents. Controlled environments provide a unique opportunity to modify the concentrations of selected phytochemicals in fruit and vegetables, yet practical information is limited regarding methods effective in optimizing antioxidant capacity. Our research at the University of Arizona Controlled Environment Agriculture Program has shown that application of moderate salt stress to tomato plants can enhance lycopene and potentially other antioxidant concentrations in fruit. The increase in lycopene in response to salt stress in the tomato fruit was shown to be cultivar specific, varying from 34% to 85%. Although the specific biological mechanisms involved in increasing fruit lycopene deposition has not been clearly elucidated, evidence suggests that increasing antioxidant concentrations is a primary physiological response of the plant to the salt stress. Another experiment showed that low temperature during postharvest increased antioxidant capacity of tomato fruit while it maintained the lycopene concentration. More detailed study in this area is needed including accumulation of antioxidant phytochemicals as affected by environmental conditions during the cultivation and the postharvest.</jats:p>

Quality of fresh‐cut tomatoes as affected by salt content in irrigation water and post‐processing ultraviolet‐C treatment

“…Tomatoes grown under water or salt stress generally develop a richer fruit color in addition to an enriched flavor. In a recent study at the Controlled Environment Agriculture Center, The University of Arizona, it was shown that lycopene concentration of tomato fruits was enhanced significantly without reducing the total fruit yield by growing plants under a moderate water stress provided by high salt concentration in the nutrient solution 20, 21. When plants were grown hydroponically using a nutrient solution with higher electrical conductivity (EC), the fruit quality was significantly greater than those grown under the standard conditions (low EC) 20.…”

Development of Systems for the Production of Plant-Derived Biopharmaceuticals

“…Greenhouses can be designed to function as containment facilities that prevent escape of transgenes [74]; they also maximize protein productivity by optimizing conditions for plant growth, development, and accumulation of nutritional compounds. Controlled environments provide an opportunity to increase production of "value-added" crops containing high concentrations of phytochemicals, such as lycopene in tomato [90]. In addition, stable transgenic plants produced by Agrobacterium-mediated transformation are usually grown in containment systems such as greenhouses.…”

Antioxidant Capacity and Antimutagenic Activity of Natural Oleoresin from Greenhouse Grown Tomatoes (Lycopersicon esculentum)

“…The lycopene content of tomatoes differs with the variety and this content also increases with ripeness of the vegetable. However, several factors influence lycopene content in tomatoes and may vary considerably from region to region, depending on growing conditions [7]. The experimental focus on lycopene should continue as it is important to capitalize on this inexpensive and abundant source of lycopene.…”