Functional foods: Genetics, metabolome, and engineering phytonutrient levels

Abstract

Phytonutrients in fruits and vegetables or their individual components (nutraceuticals) positively contribute to human health. Mostly, these nutrients have antioxidative property that impacts redox imbalance and can lead to prevention of cancer, cardiovascular diseases, diabetes, osteoporosis, and age-related disorders such as dementia. Over 7,000 flavonoids (and phenolic compounds) and 600 naturally occurring carotenoids seemingly with health benefits have been documented in plants. Fruits and vegetables are dietary sources of pro-health nutrients (nutraceuticals); however, the level of an individual antioxidant is low in the currently used germplasm, thus limiting them in meeting the recommended daily allowance (RDA). Nonetheless, the awareness about their health benefits has increased the global demand for and consumption of fruits and vegetables. Advanced molecular breeding and genetic engineering approaches are providing novel tools to greatly increase the levels of many desirable nutraceuticals, which is being made easier because their metabolic pathways are now known. The biotechnological interventions have already allowed severalfold increases in the content of flavonoids and carotenoids in fruit crops and essential fatty acids in oil crops. This chapter gives an overview of three classes of phytonutrients – flavonoids, carotenoids, and essential fatty acids, their dietary sources, metabolic pathways, and important genes/enzymes involved in their production. Several examples of the biotechnological intervention to boost endogenous levels of phytonutrients in various crop plants are highlighted.