Plant technology increases vitamin C levels

Biochemists at the University of California have developed a technology that increases the amount of vitamin C in plants, including grains. The researchers increased the amount of the enzyme that is responsible for recycling vitamin C, leading to plants with higher nutritive value.

Vitamin C, or ascorbic acid, is essential to cardiovascular and immune cell function and is also used to regenerate vitamin E. The vitamin is present at high levels in some fruits such as citrus and some green leafy vegetables, but present in low levels in grains widely used in modern foods.

"Once used, vitamin C can be regenerated by the enzyme dehydroascorbate reductase or DHAR,"​ explained Daniel Gallie, lead researcher. "Through this means, plants recycle the vitamin so that it can be used repeatedly. If vitamin C is not salvaged by DHAR, it is quickly lost."​

Writing in the Proceedings of the National Academy of Sciences​, the authors tried increasing the amount of DHAR in plants with the aim of improving their ability to recycle vitamin C and thereby increase its amount. The researchers introduced the gene encoding DHAR from wheat into corn to increase the amount of DHAR by up to 100-fold.

"We found that the increase in DHAR elevated the amount of vitamin C in grain and leaves of corn, showing that the vitamin C content of plants can indeed be elevated by increasing expression of the enzyme responsible for recycling the vitamin,"​ said Gallie.

The researchers achieved similar results using a member of the solanaceae family (this family includes potatoes and tomatoes), which was used as a model for non-grain crops.

"This technology improves nutrition by increasing the number of foods from which the vitamin can be obtained as well as increasing the level of the vitamin in those foods which are already good sources of vitamin C,"​ said Gallie.