%0 Journal Article
%T L-Ascorbic Acid: A Multifunctional Molecule Supporting Plant Growth and Development
%A Daniel R. Gallie
%J Scientifica
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/795964
%X L-Ascorbic acid (vitamin C) is as essential to plants as it is to animals. Ascorbic acid functions as a major redox buffer and as a cofactor for enzymes involved in regulating photosynthesis, hormone biosynthesis, and regenerating other antioxidants. Ascorbic acid regulates cell division and growth and is involved in signal transduction. In contrast to the single pathway responsible for ascorbic acid biosynthesis in animals, plants use multiple pathways to synthesize ascorbic acid, perhaps reflecting the importance of this molecule to plant health. Given the importance of ascorbic acid to human nutrition, several technologies have been developed to increase the ascorbic acid content of plants through the manipulation of biosynthetic or recycling pathways. This paper provides an overview of these approaches as well as the consequences that changes in ascorbic acid content have on plant growth and function. Discussed is the capacity of plants to tolerate changes in ascorbic acid content. The many functions that ascorbic acid serves in plants, however, will require highly targeted approaches to improve their nutritional quality without compromising their health. 1. Introduction Vitamin C (L-ascorbic acid) is a water-soluble antioxidant that serves a predominantly protective role. Despite the fact that most mammals can synthesize ascorbate (Asc), humans (along with other primates, bats, and guinea pigs) are unable to make vitamin C as a result of a mutation to the gene encoding L-gulono-1,4-lactone oxidase, the last enzyme in the Asc biosynthetic pathway [1]. Although the symptoms associated with severe vitamin C deficiency, for example, weak joints, bleeding gums, and skin discoloration due to ruptured blood vessels, had been observed and described as early as 1497 by Vasco da Gama among his crew during their voyage around the southern tip of Africa to India, it was not until 1747 that James Lind demonstrated that consumption of citrus fruit prevented or cured the disorders associated with scurvy. Because of this, vitamin C was originally referred to as the ˇ°antiscorbutic factor.ˇ± Vitamin C (L-threo-hex-2-enono-1,4-lactone) was eventually isolated in 1928 by Dr. Szent-Gyorgyi although he was uncertain of its function. Only in 1932 did crystallization of the physiologically active compound isolated from natural sources identify the antiscorbutic factor as vitamin C [2¨C4], and its structure determined the following year [5]. In animals, ascorbate is involved in the synthesis of carnitine and collagen, an important component of skin, scar tissue, tendons,
%U http://www.hindawi.com/journals/scientifica/2013/795964/