Physiological Processes Contributing to the Synthesis of Ascorbic Acid in Plants

Abstract

Ascorbic acid (AA) is present in high concentration in plant tissues andparticipates of many vital processes. Its biosynthetic pathway in plants has beenrecently established. Nowadays, research is focused on understanding the regulationof this pathway. One of the aspects is to unravel the importance of each enzymethrough the establishment of limiting reactions and specific controlling processes.Interestingly, the synthesis of AA presents a high interaction with several physiologicalprocesses. The photosynthetic activity directly affects AA synthesis, and thelast reaction of its formation takes place in mitochondria depending on the mitochondrialelectron transport chain. In addition, it is now known how some planthormones regulate this pathway. The incident light constitutes a key environmentalfactor controlling the synthesis of AA in plants. Light regulates the levels of severalenzymes, but its effect on AA biosynthesis is also mediated through modificationsin the previously mentioned physiological processes. The knowledge about theregulation of AA synthesis will allow the development of manipulative strategiesleading to effectively increase the concentration of AA in edible plant organs.