A daily potato for all your vitamin C needs

In the future, it may be possible to get your daily dose of vitamin C from just one potato.

Scientists at Plant & Food Research are investigating how vitamin C is made in plants and have identified the gene that controls the level of vitamin C in fruits and vegetables.

“Vitamin C is essential in the human body to ensure healthy cell function, but humans have to get vitamin C, or ascorbate, from their diet, as our primate ancestors lost the ability to synthesise it in the body,” says Dr William Laing, lead scientist on the study. “Consequently, humans obtain most of their vitamin C from plant sources but, as many food sources are relatively low in vitamin C, many people add to their vitamin C intake with synthetic supplements.

“By understanding how vitamin C levels are controlled in plants, particularly in the edible fruits or tubers, there is potential to develop new varieties of common crops with higher levels of natural vitamin C.”

The science team artificially added a plant gene controlling GDP-galactose phosphorylase (GGP), an enzyme important in the production of vitamin C, to different varieties of strawberry, potato and tomato. The results, published in the Plant Biotechnology Journal, showed that ascorbate levels could be increased by up to 500%.

“These experiments suggest that new varieties of plants could be bred that produce enough naturally occurring vitamin C that the recommended daily amount could be achieved by eating, for example, only one average-sized potato,” continues Dr Laing. “These new varieties would have the potential to reduce vitamin C deficiency in populations with reduced access to fruits and vegetables by allowing them to meet recommended levels through consumption of potatoes and other staple foods.”

Identification of the gene can also be used to develop molecular markers that allow Plant & Food Research scientists to screen parents and offspring in its natural crop breeding programme and identify those with the genetic potential to produce high levels of vitamin C.

“Consumers in many countries, including New Zealand, have concerns about the inclusion of transgenic foods in their diet, so the next challenge is how to use this genetic information to speed up the breeding of new non-transgenic varieties with naturally-high levels of vitamin C,” says Dr Laing.