Ascorbate as a biosynthetic precursor in plants

Abstract

BACKGROUND AND AIMS: L-Ascorbate (vitamin C) has well-documented roles in many aspects of redox control and anti-oxidant activity in plant cells. This Botanical Briefing highlights recent developments in another aspect of L-ascorbate metabolism: its function as a precursor for specific processes in the biosynthesis of organic acids. SCOPE: The Briefing provides a summary of recent advances in our understanding of L-ascorbate metabolism, covering biosynthesis, translocation and functional aspects. The role of L-ascorbate as a biosynthetic precursor in the formation of oxalic acid, L-threonic acid and L-tartaric acid is described, and progress in elaborating the mechanisms of the formation of these acids is reviewed. The potential conflict between the two roles of L-ascorbate in plant cells, functional and biosynthetic, is highlighted. CONCLUSIONS: Recent advances in the understanding of L-ascorbate catabolism and the formation of oxalic and L-tartaric acids provide compelling evidence for a major role of L-ascorbate in plant metabolism. Combined experimental approaches, using classic biochemical and emerging ‘omics’ technologies, have provided recent insight to previously under-investigated areas.