Researchers from the University of Exeter and Shimane University said their finding could have implications for agriculture and for the production of vitamin C dietary supplements.

The study describes the newly-identified enzyme GDP-L-galactose phosphorylase, which produces vitamin C in plants. Vitamin C is already known to be an antioxidant, which helps plants deal with stresses such as drought, ozone and UV radiation. But this is the first indication plants need it to grow.

"Vitamin C is the most abundant antioxidant in plants and yet its functions are poorly understood," said Professor Nicholas Smirnoff of the University of Exeter, lead author of the study. "By discovering the new enzyme is encoded by two genes, we were able to engineer vitamin C-free plants and found that they were unable to grow."

The research also identifies the new enzyme as a key player in controlling vitamin C accumulation in response to light.

The findings appear in the online edition of The Plant Journal.