Ascorbate biosynthesis in Arabidopsis cell suspension culture

The biosynthesis of L-ascorbic acid (L-AA) in an Arabidopsis (L.) Heynh. ce ll suspension culture was studied by quantifying the effects of incubation with a range of potential biosynthetic precursors, analogs, and inhibitors on the intracellular levels of reduced and oxidized forms of L-AA. Our resu lts support the recently published biosynthetic pathway of L-AA from L-gala ctose (G.L. Wheeler, M.A. Jones, N. Smirnoff [1998] Nature 393: 365-369), b ut suggest that Arabidopsis cell suspension culture simultaneously contains two other routes leading to L-AA. The possible physiological significance of these alternate routes is discussed.