Plant Vitamin C: One Single Molecule with a Plethora of Roles

Ascorbic acid or vitamin C is one of the most abundant water-soluble low molecular weight antioxidants present in living tissues, exerting a pivotal role in the detoxification of reactive oxygen species (ROS) generated following exposure to environmental changes or biotic stress factors. This chapter illustrates the multiple roles of L-ascorbic acid (AsA), as well as its genetic regulation in plant tissues with a focus on fruits and vegetables. The AsA content of fruits and vegetables is important from an agronomic point of view, not only because AsA is a marker for nutritional quality, but also because high AsA contents are correlated with increased resistance to stress, and possibly with improved postharvest shelf life. As AsA is highly abundant in leaf tissues and in particular in the chloroplast stroma, it is considered the major antioxidant in plant tissues. As an antioxidant, AsA is able to accept electrons from a wide range of radical substrates.