Identification of potential gene targets for the improvement of ascorbate contents of genetically modified plants

Abstract

Up to half of the ∼6.8 billion people living on planet earth live on less than $3 a day and also suffer from at least one micronutrient deficiency especially in Africa and Southeast Asia. Human lacks the capacity to synthesize vitamin C (ascorbic acid) and its deficiency causes scurvy. As excess vitamin C cannot be stored in the human's body, there is the need to regularly consume fruits and vegetables to supply this essential compound. In plants, it is multifunctional and indispensable. Overexpression of heterogonous genes to introduce novel traits into plants offers an effective way to increase the vitamin content of crops. Although many alternative biosynthesis routes for vitamin C have been proposed, the Smirnoff-Wheeler (l-galactose) pathway has been proven to be the functional pathway in Arabidopsis and many other fruit-bearing plants. Identifying limiting genes in the biosynthesis pathways and overexpression of such genes severally and collectively as well as in combination with genes from ascorbate recycling pathway may lead to the generation of transgenic plants with 'substantial' amount of vitamin C for both human nutrition leading to reduced 'hidden hunger' and agronomic purposes. Proper dissemination of scientifically proven safety information about such transgenic plants will also increase public confidence in selecting and consuming such nutritionally enhanced genetically modified food crops.