Potential for engineering horticultural crops with high antioxidant capacity.

Cellular oxidation index has emerged as an important determinant in defining the fate of a living cell and its susceptibility to disease. Oxidative stress targets include oxidation of DNA, protein and lipids; causing cellular oncogenesis, chronic diseases and premature senescence. The possibility that dietary intervention via nutrition-enriched food may significantly decrease incidence of diet-related diseases has catalysed scientific efforts to understand this relationship, which is fundamental to developing future strategies for stemming disease. Multiple and synergistic interactions among nutrients influence antiproliferative activity of a fruit compared with an isolated antioxidant. Nutritional molecules including vitamins (B, C, E and beta-carotene), folates, lycopene, flavonoids, isothyocyanates, glucosinolates, polyphenols, glutathione and minerals contribute to the antioxidative capacity of vegetables, fruits, nuts and various herbs. The true potential of a supplemental antioxidant or crop nutrients in human health benefits is in their accessibility, bioavailability and biological potency. Studies on the absorption, metabolism and <i>in vivo</i> potency of phytonutrients have lagged behind and are only now beginning to provide some results. Also, it is important to bear in mind that the levels of phytonutrients present in horticultural crops are low and significantly influenced by genotype/cultivar, growth condition and developmental stage. In this regard, genetic engineering has become a refined tool to increase the antioxidant and nutrient capacity of economically important crops including fruits and vegetables to the levels favourable not only for a highly nutritional diet but also to enable in-depth studies on the relationships between diet, genetics and metabolism. Together with modern biotechnology, deciphering transcriptome-proteome-metabolome of the new transgenics should provide new knowledge to ease the concerns of the society and open the market for genetically engineered horticulture crops, as is seen by higher sales of Hawaii-grown transgenic papaya in the USA. Also, this knowledge will help us in developing precise strategies for redesigning metabolic pathways so that desired levels of a particular phytonutrient (antioxidant) in crops are achieved.